Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session G00: Poster Session I (2pm-5pm PST)Poster Undergrad Friendly
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Sponsoring Units: APS Room: Exhibit Hall (Forum Ballroom) |
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G00.00001: UNDERGRADUATE RESEARCH
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Author not Attending |
G00.00002: Achieving robust topological phases and qubit operations in the presence of long-range interactions Anaida Ali, Eran Ginossar We theoretically explore 1D p-wave superconductors and dimerized chains in the presence of long-range couplings to achieve richer topological phases. We find that different regimes of long-range couplings yield non-trivial topological phases that inherit zero modes and massive edge modes. We find that long-range hopping in dimerized chains leads to multiple zero-modes whereas previously observed long-range pairing in p-wave superconductors gives rise to localized non-zero edge modes with fractional winding numbers. We characterize the topological origin of these phases using winding numbers and entanglement entropy. We further study the scope of quench dynamics of the entanglement spectrum as a signal to identify topological phase transitions in our models. Motivated by the above results, we extend our studies toward achieving robust single and multiqubit operations in our 1D models. |
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G00.00003: Characterizing the Relationship Between Temperature and Anisotropic Magnetoresistance in Manganite Thin Films Jonah W Beurkens Manganite thin films have been extensively studied for their wide range of potential applications in solid-state data storage and correlated electron devices. One lesser-explored property of manganites is anisotropic magnetoresistance (AMR), or electrical resistance that changes as a function of the angle between the manganite sample and an applied magnetic field. AMR can reveal certain underlying phenomena in magnetic materials and is also relevant for potential applications. We develop a convenient method for measuring the AMR of thin film samples using a home-built cryostat, which allows for large sample sizes, and a LabView program to collect data. Then, we investigate the dependence of AMR on temperature in a La0.7Ca0.3MnO3 (LCMO) thin film and analyze it using a phenomenological model. We find that there is an overall inverse relationship between sample temperature and resistance anisotropy with the exception of one anomalous temperature at 100 K. We present a possible explanation for this relationship, wherein competing ferromagnetic metallic and insulating phases within the material lead to the temperature dependence of AMR in LCMO. |
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G00.00004: Preparation of Gold Films on MoS2 with Subatomic Surface Roughness by Sputtering Jeff Carlson, Andrew J Stollenwerk, Tim E Kidd We have determined that gold films with subatomic surface roughness can be prepared onto MoS2 surfaces using a simple sputtering process at room temperature. To explore integration with semiconductor devices and/or substrates for further growth, the used substrates were either standard silicon wafers with a native oxide (SiO2/Si), or MoS2 bilayers sputtered onto such silicon wafers (MoS2/SiO2/Si). It was immediately apparent that the gold deposited onto the MoS2/SiO2/Si substrates were far superior. Gold films deposited onto bare silicon wafer substrates had nanometer scale (or larger) RMS surface roughness. Gold films deposited on the sputtered MoS2 bilayers had RMS surface roughness of less than 300 pm. For gold films with thicknesses between 10 to 15 nm, the surface roughness was consistently less than 100 pm, which is approximately the resolution of the atomic force microscope (AFM) used in these experiments. It was especially interesting to see that the gold films were flatter than both the native oxide of the silicon wafer and the sputtered MoS2 bilayers. We found no evidence for granular structure even for AFM scans exceeding 100 square microns. Our ultraflat gold films should be highly useful for any research requiring extremely smooth surfaces, such as the exploration of self-assembled monolayers. We also found that the surface roughness is easily tunable by annealing above 200° C, making them potentially useful for substrates utilizing surface enhanced techniques such as Raman spectroscopy. |
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G00.00005: Effect of the gate voltage scan rate on charge transport in graphene that is gated with an ionic liquid Nicholas J Pinto, Elvin Cordero Figueroa, Chengyu Wen, A T Charlie Johnson Charge transport in CVD graphene was investigated at room temperature using a field effect transistor platform with an ionic liquid (IL) as the gate material. Using an IL lowers the gate voltage needed for device operation due to its high specific capacitance. Impurity charges adsorbed on the graphene surface during growth and post processing act as dopants and influence charge transport. Applying a voltage to the IL (VG) changed this impurity charge concentration and shifted the charge neutrality point (CP) in graphene. In this work we varied the gate voltage scan rates from 100 mV/s to 1 mV/s and examined its effect on the channel current (I). Lowering the scan rate led to the following observations in the I-VG plots: (i) a non-linear shift in gate voltage at the CP voltage from a positive value toward VG = 0 (i.e. n-doping), (ii) an increase in the electron and hole mobilities and (iii) a narrowing of the spread in the current near the CP. We believe that a slower scan rate helped create a more uniform electric double layer at the graphene/IL interface which could neutralize impurity charges. The result was a homogeneous redistribution of un-neutralized impurity charges and a reduction in charge scattering of carrier charges. By using an IL that selectively absorbs gas species, our device can also be used as a gas sensor. The low applied voltages in combination with transistor operation make this device multifunctional and suitable in battery powered electronics. |
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G00.00006: Rapid Vaporization of Activated Lithium for Detector Testing Jessica M Dawson, Johnathan Conway, Noah M Dauphin, Nicole M Lallier, Julia G Tufillaro, Carleigh B Wachtel, James G McLean, Stephen J Padalino, Chad J Forrest, Sean P Regan A system has been developed that uses high current to rapidly and consistently vaporize activated materials which have been coated onto a tungsten ribbon filament. This system will be used to test the Short-Lived Isotope Counting System (SLICS), which is being developed to measure the quantity of short-lived radioactive fusion products created in the Laboratory for Laser Energetics (LLE) Omega facility. SLICS is tested with simulated fusion products by capturing rapidly vaporized materials after activation with a beam in the SUNY Geneseo Pelletron accelerator. Using lithium as the target material for a deuteron beam, lithium-8 is produced and decays through beta emission with a half-life of 838 milliseconds. The vaporization system uses a thyristor to quickly discharge high-voltage capacitors, delivering 500-1000 Amps of current through tungsten filaments during a 5-15 millisecond time period. The maximum temperature of the filament, and therefore the vaporization rate of the lithium, depends on the capacitor voltage, ribbon geometry, and conductance of the coating. The relationships between these parameters are reported for uncoated tungsten filaments. |
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G00.00007: Understanding the Scattering by Polystyrene Microspheres Collin P Douglas, Patrick Herron, Kiril A Streletzky Using scattering methods (Static Light Scattering (SLS), Dynamic Light Scattering (DLS), and Small Angle X-ray Scattering (SAXS)) we studied the structure and dynamics of polystyrene microspheres of various sizes in suspensions of different concentrations as a model system for polymeric microgels studied/to be studied with the same methods. SLS utilizes average light scattering off samples at varying angles to determine the sample's molecular weight (Mw) and radius of gyration (Rg) using Zimm analysis. The samples form factor (P(q)), the ratio of intensity to zero angle intensity, was also determined and plotted against known form factors of simple geometrical shapes using Kratky plots. SAXS is similar to SLS but should provide a greater resolution for particle structure over a wider size range. DLS utilizes fluctuations of scattered light to determine particle diffusion and hydrodynamic radius (Rh). Mw and Rh can then be utilized to determine the apparent density (ρ) of the spheres. In this project, we were able to confirm by SLS and DLS the spherical shape and accepted sizes of microspheres. However, the methods became less accurate in determining Rg and Mw for larger and extremely low concentrations of microspheres, which is expected. Issues with low concentration emphasize the need for sample filtration while scattering by larger probes illustrated the resolution limit of light scattering setup and the strong effect of sample polydispersity. SAXS is being performed to obtain Rg, Mw, and ρ with an improved resolution for comparison with light scattering. |
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G00.00008: Applying Kernel Ridge Regression to Predict Dielectric Properties of Ceramic Oxides Luke H Elder, Daniel T Hickox-Young As renewable energy sources become more prevalent, the demand for energy storage devices with large energy storage capacity and high power density has also increased. These ultrahigh capacitance energy storage devices require materials with the rare combination of a large dielectric constant and high dielectric strength. We use kernel ridge regression to predict new ultrahigh capacitance materials, focusing our search on oxides with the general formula ABOn (where 1 ≤ n ≤ 4) and primarily using compositional information to train the model. We systematically vary the training data in order to investigate the interplay between oxide composition and dielectric behavior before using our top-performing model to predict the dielectric constant and band gap for new compositions. After identifying several promising materials, we use DFT calculations to validate our predictions. |
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G00.00009: Investigation on exciton-phonon optical properties and Raman shift in hexagonal Boron Nitride (hBN) monolayers using Raman spectroscopy and photoluminescence measurement towards non-cryogenic operation Jonas Flann Two-dimensional solid-states systems possess versatile properties that can be exploited for various applications in optoelectronics and quantum communications. Among different two-dimensional systems, hexagonal Boron Nitride monolayers are promising due to their graphene-like crystallinity which can mitigate the interfacial differences between graphene and conventional substrates. Moreover, owing to their large bandgap energy, single-photon emissions have been observed from defect-centers of hexagonal Boron Nitride at room-temperature. Understanding the role of exciton-phonon couplings near the defect-centers is important due to the decoherence mechanism of quantum optical properties and for operation at non-cryogenic temperature. Our work will show various optical properties of hexagonal Boron Nitride monolayers using Raman spectroscopy and Photoluminescence measurements. We show correlations between Raman shifts and the layer thickness and discuss exciton-phonon interactions near single photon emitter defect-sites via temperature dependent Photoluminescence measurement. |
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G00.00010: Mechanochemical activation of yttrium iron garnet with and without graphene nanoparticles Sarah L Glasser, Monica Sorescu Nanoparticles systems of yttrium iron garnet with and without graphene were exposed to mechanochemical activation by high-energy ball milling for 0, 2, 4, 8 and 12 hours. The samples were characterized by Mossbauer spectroscopy. The 0-h specimens were analyzed by considering 2 sextets, corresponding to the tetrahedral and octahedral sites of the yttrium iron garnet. The spectra of the milled samples were fitted with a third sextet with the hyperfine magnetic field characteristic to hematite and a quadrupole-split doublet representing superparamagnetic particles of the yttrium perovskite (orthoferrite) phase. The mechanism of ball milling activation was found consistent with the decomposition of the garnet into yttrium perovskite and hematite. A plot of the quadrupole doublet's abundance as function of ball milling time indicated that graphene retarded the precipitation of the perovskite. The increased linewidth of the doublet showed that carbon from graphene entered with preference the lattice of the yttrium orthoferrite. |
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G00.00011: Reduced graphene oxide on silicon heterojunction for self-powered photodetection Jose L Gordillo A heterojunction diode was fabricated by depositing reduced graphene oxide (rGO) on n-type silicon. The device was exposed to UV irradiation for periods of up to 10 min and temperatures between 50 K and 350 K. The current-voltage measurements show an increment in conductivity with UV irradiation of 365 nm in the whole temperature range. The photoresponse with no external bias (self-powered) shows maximum responsivity and detectivity of 0.2 A/W and 7.5x109 Jones, respectively, at 223 K. The response and recovery times for on-off switching of UV light range from 20 to 50 ms. The rGO, obtained from hydrothermal carbonization of sucrose, can be produced at low-cost cost and with high yields, and is compatible with silicon device technology. The results indicate that the rGO-based device can be useful for self-powered photodetection. We will present our analysis on temperature-dependent photoconduction mechanisms. |
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G00.00012: One-Dimensional and Two-Dimensional Simulations of Helical Homopolymers: A Comparative Analysis of Efficiency and Funnel Folding Matthew Hooks, Nathan L Roberts, Matthew J Williams The purpose of our work is to analyze the results of a two-dimensional parallel tempering simulation of a coarse-grained helical homopolymer. We aim to measure the efficiency of the simulation and apply this efficiency to the theoretical protein free energy landscape.The stable states for helical homopolymers will be analyzed using the folding funnel theory of free energy landscapes for given polymer configurations. The genesis of each simulation is defined by a randomly configured polymer; as time progresses, the energy of each structure decreases until equilibrium is reached. Data collected after equilibrium is reached is used to understand polymer behavior for each model and simulated temperature. A rolling average algorithm has been designed to establish the time step at which energy stabilization is reached for each model. The simulation is considered to be stable when the rolling average of the energy is within a set fraction of the standard deviation of the rolling window based on the standard deviation and mean of previous windows. Efficiency and equilibration time of the 1D and 2D simulations are compared to determine the value of the two dimensional exchange scheme and analyze the free energy landscape of the polymer configuration. |
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G00.00013: Diffusion Coefficient for Electron Transport Simulation Virginia Jarvis The Monte Carlo method can be used to directly solve the Boltzmann equation by randomly producing trajectories to obtain a distribution of solutions. The group wrote a simulation which intends to accomplish this for the travel of electrons through an Arsenic-doped Silicon lattice. This information can be used to learn more about the behavior of charge carriers as they travel through the lattice, to study the effect of energy band warping on transport, and to help in potential applications for semiconductor devices. Verification of the simulation’s success includes comparing with known constants such as drift velocity, free flight time, and diffusion coefficient. We calculated the diffusion coefficient, an important physical quantity that describes the way charge carriers move through a material, in Mathematica using the positions generated by this simulation to determine spatial concentrations to compare with solutions to Fick’s second law. Testing of the method was performed using positions generated by a Random Walk. After producing diffusion coefficients, we studied the relationship with temperature at 50K, 300K, 550K, and 800K as well as change in ion impurity concentration at 1013, 1015, and 1017 ions/cm3 over electric field strengths of 10 000, 510 000, and 1 010 000 V/m. |
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G00.00014: Transport Behavior of Planar Fe3GeTe2 Josephson Junctions Lillian C Jirousek, Kevin M Ryan, Venkat Chandrasekhar Josephson coupling of superconductors through novel 2D vdW systems can produce interesting phenomena not seen in traditional junctions. Fe3GeTe2 (FGT) for instance, is a magnetic semimetal with tunable ferromagnetism[1] and has been shown to exhibit large spin-polarization and spin-valve behavior in In based planar junctions[2]. Here we report on vdW based superconducting ferromagnetic superconducting (SFS) devices, through the construction and transport measurement of Al/FGT/Al junctions. Given the observed gate tunable magnetism, such a device may provide for electronic control of the in field transport behavior of such devices. |
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G00.00015: Diffusion of Carbon Nanoparticles Intercalated into Layered Materials Madelyn Johnson, Timothy E Kidd, Amber Hartness We have discovered a method using electron beam radiation, as found in a scanning electron microscope (SEM), to locally induce intercalation of carbon nanoparticles into the two dimensional layered materials. This technique can be used to form insulating and optically active nanostructures in samples ranging from graphite to BSCCO. In this study, we explore how these features evolve with time. we find that, over the course of days and weeks, the nanostructures created this way broaden and change height. In general, it appears that the nanoparticles respond to local strain and spread out to reduce their concentration in a given area. The process proceeds most rapidly in more defective crystal structures like TiS2 and most slowly in rigid oxides like BSCCO. We hope to utilize this work to determine the overall stability of these structures and their utility to form nanoscale devices like josephson tunnel juntcions. |
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G00.00016: Synthesis and Characterization of a High-Entropy Spinel Oxide Single Crystal Evan Krysko, Lujin Min, Yu Wang, Na Zhang, Mauricio Terrones, Zhiqiang Mao High-entropy materials generally refer to compounds which involve mixing five or more elements in nearly equimolar concentrations at an equivalent atomic site. These compounds are stabilized into a single phase by the high configurational entropy caused by the varying sizes and masses of their constituent elements. Prior work has shown competing magnetic interactions enabled by high entropy generate novel magnetic phases. Given that oxides with the spinel structure contain a variety of magnetic ordering, high-entropy spinel oxides, if successfully made, would provide a platform for the further study of high-entropy tuning of magnetism. This research aimed to synthesize a novel high-entropy oxide with the spinel structure and to determine the effects of its lattice distortions on its magnetization. In this work, an (Mg, Mn, Fe, Ni, Co)Al2O4 single crystal was synthesized for the first time using the optical floating zone growth technique. The sample was confirmed to be a phase pure high-entropy oxide (HEO) using X-ray diffraction (XRD) and energy-dispersive spectroscopy (EDS). Through magnetization measurements, we found (Mg, Mn, Fe, Ni, Co)Al2O4 exhibits a spin-glass state though the parent phases show either antiferromagnetic or ferrimagnetic ordering or spin glass. Furthermore, we also found that (Mg, Mn, Fe, Ni, Co)Al2O4 has much greater thermal expansion than its parent compounds from neutron scattering measurements. |
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G00.00017: Optical response of relativistic-like materials using Fourier Transform Infrared spectroscopy Megan Loh Optics offer a powerful lens for understanding the physical properties of crystalline materials that exhibit exotic phenomena, such as topological insulators and Weyl and Dirac semimetals. Fourier Transform Infrared (FTIR) spectroscopy detects electronic and vibrational transitions in the sample through the absorption or reflection of an incident light beam. |
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G00.00018: Growth of Double Perovskite A2BB’O6 Single Crystals in various Fluxes Austyn N McIntyre, Tiglet Besara Double perovskites of the form A2BB’O6, which mimic a rock-salt type structure with BO6 and B’O6 octahedra, are rapidly emerging materials due to their versatility and possible applications in multiferroics, photovoltaics, spintronics, to name a few. Single crystals of double perovskites have been produced by the flux growth method. Flux synthesis is an extremely advantageous and widely applied growth method to produce high-quality single crystals while controlling the temperature and rates of heating and cooling. Growth of single-crystalline double perovskites was attempted with two methods: solid state synthesis using oxides which was subsequently used as precursors in a molten flux to form single crystals, and oxides directly in a molten flux without prior solid state synthesis. Major considerations include the reaction vessel, the growth environment (air/vacuum/argon), interaction between cations and chosen flux, temperature, dwell time, and heating and cooling rates. Attempts, challenges, and potential directions are discussed. |
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G00.00019: 1D Confinement of 4He Inside Cesium-Plated MCM-41 Nanopores Stephanie McNamara
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G00.00020: Magnetic Properties of FeCrVAl-Based Materials Young Moua, Zachary Pottebaum, Paul M Shand, Pavel Lukashev, Parashu R Kharel, Gavin M Baker, Jax G Wysong
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G00.00021: Exploration of Relationship Between Phonons and LiFePO4 Cathode Behavior using Density Functional Theory Solomon R Murdock, Hillary L Smith LiFePO4 is a widely used battery cathode material. During electrochemical cycling of LiFePO4, energy is generated via reversible delithiation and lithium intercalation, forming an intermediate mixture of LiFePO4 and FePO4 during charging and discharging. While it is known that lithium ions migrate in and out of the material along the b-axis, the effect of lattice vibrations on ion migration is not understood. Ab initio Density Functional Theory calculations have been used to determine the phonon dispersions and density of states of LiFePO4, FePO4, and an intermediate phase. We compare these calculations to inelastic neutron scattering measurements of single crystalline LiFePO4 to gain insight into the influence of lattice dynamics on ion mobility. Thermal effects including the phonon energy evolution and temperature dependent lifetime information will also be discussed. |
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G00.00022: Dielectric Characterization of h-BN by Preparing Metal-Insulator-Metal Capacitors Bhavana Panchumarthi While hexagonal Boron Nitride (h-BN) mostly debuted in the 2D-materials research world as a substrate and an insulator, it has recently emerged as a material with great potential applications: ranging from nanoelectronics to single photon emission. Some of its noteworthy properties are electric insulation, low dielectric constant, easy synthesis, high-temperature stability, corrosion resistance, and chemical stability. Given this attention, CVD h-BN films have started to become commercially available. In this study, the topographic and electronic features of CVD h-BN films are characterized using probe microscopy techniques including conductive atomic force microscopy and Kelvin probe force microscopy. Then, we quantify the out-of-plane dielectric constant of CVD h-BN films by preparing Metal-Insulator-Metal (MIM) capacitors using thermally evaporated metal deposition. Together these results lead to a deeper understanding of the CVD h-BN film and of its application in electronic devices. |
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G00.00023: Effect of Post-Deposition Thermal Treatments on the Structure and Properties of Metal Oxide Thin Films Taylor Pettaway, Ryan S Paxson, Joseph Kromer, David Schaefer, Rajeswari M Kolagani Metal Oxide thin films belonging to the ABO3 perovskite family of materials have many important applications including use in renewable energy technologies. Material properties needed for these applications can be optimized by varying the chemistry of these samples, oxygen content being an especially important parameter. Oxygen content in thin films can be varied using post-deposition thermal treatment ( annealing) in different ambients. I will present our research results on the effect of post-deposition thermal processing on the properties of thin films of the perovskite oxide materials La0.67Ca0.33MnO3 and SrTiO3 in different oxidizing and reducing gas ambients. Properties of interest include electrical resistivity, crystal structure and surface morphology. Electrical resistivity is measured by DC four probe method, crystal structure is determined by x-ray diffraction and surface morphology is analyzed using atomic force microscopy. Our initial studies indicate that annealing in an oxygen rich environment results in a shortening of the c-axis lattice parameter of La0.67Ca0.33MnO3 thin films. |
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G00.00024: Computationally Modeling the Magnetization of Ca3Co2O6 Nicolas Puentes Magnetic materials play integral roles in emerging technologies including sensors and spintronic devices used in quantum computing. Understanding the thermodynamic properties of magnetic materials is essential to enabling technological advancements. The phase diagram of Ca3Co2O6 exhibits several regions of nontrivial competition between nearly-degenerate magnetic orders. This is a consequence of Co2O6 chains forming a triangular lattice with ferromagnetic intrachain and antiferromagnetic interchain interactions and two distinct cobalt sites with different local symmetry. The goal of this research project was to investigate the magnetic phase diagram of Ca3Co2O6 by modeling its magnetization, and the magnetic plateaus that are present, with Monte Carlo simulations. Ca3Co2O6 is reduced to a two-dimensional triangular lattice by representing each chain as a rigid spin with antiferromagnetic Ising interactions since the ferromagnetic intrachain interactions are much stronger than interchain interactions. A random-exchange term was also included to account for defects and inhomogeneities. Including a random-exchange term quantitatively improved agreement with measured magnetization data by rounding magnetic steps. The simulated magnetic phase boundaries quantitatively disagreed with published phase diagrams. This discrepancy is likely caused by representing the chains as rigid spins, which oversimplifies the complex inter and intrachain interactions. |
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G00.00025: Highly and Transparent Supramolecular Fibrils of Tyrosine Jeiko Pujols Various peptides and amino acids can self-assemble into fibers in a solution. These fibers can aggregate as amyloid in the organs of individuals with a certain genetic mutation and are therefore biocompatible. In this study we observed the mechanical properties of self-assembled fibrils of enantiomers of tyrosine, one of the essential aromatic amino acids found in living systems. We found the Young’s modulus of L-tyrosine fibers to be as high as 43 GPa with a point stiffness of 454 N/m. Young's modulus of D-tyrosine fibers was found to be approximately half that of L-tyrosine but significant nonetheless. These results demonstrate that tyrosine can form highly rigid bio-inspired structures. We also observed that films of L- tyrosine fibers have a transmittance of 65% while films of D-tyrosine fibrils and films from an equimolar mixture of both enantiomers were opaque. The study shows that chirality of the amino acids affects the molecular packing during supramolecular assembly resulting in structures with varying mechanical and optical properties. |
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G00.00026: Non-Brownian Motion of Janus Particles in liquid crystals Sam Rubin, Antonio Tavera-Vazquez, Gustavo Perez, Walter Alvarado, Juan J De Pablo Inspired by micro-swimmers in nature, significant studies on non-Brownian particles have been developed in the last decade. Examples include experiments conducting self-propelled colloids primarily suspended in water-like mixtures, activated by different methods. Rather than using water as a solvent, we choose to use a nematic structured medium. In this work, we implement microscopic Janus silica particles half-coated with titanium, immersed in a thermotropic liquid crystal. When the sample is heated slightly below the nematic-isotropic (NI) phase transition, the Janus particles’ mobility is triggered by light. The titanium side of the colloids is heated, thereby surpassing the isotropic temperature threshold. Consequently, the colloids use the localized NI phase transition to self-propel through the liquid crystal. Implementing particle tracking analysis allows us to further study the colloids’ patterns of movement. Accounting for birefringence intensity and particle rotation helps to predict the particles’ trajectories. In addition, we make a comparison between the Brownian case and the activated colloids. Our studies foster a better understanding of predicting trajectories in micro-swimmers immersed in structured media at the NI phase transition. |
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G00.00027: Investigation of quantum materials using p-block fluxes August J Schwoebel, Tiglet Besara Exploratory single crystal growth of intermetallic compounds opens the possibility for discovering new materials with interesting physical properties, such as superconductivity, topology, thermoelectricity, etc. Current investigations involve the use of p-block metals and metalloids as either passive or active fluxes for discovering ternary compounds with rare-earth and transition metals. Here, we report on the synthesis, structural characterization via x-ray diffraction and Raman spectroscopy, and exploration of physical properties of new materials. |
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G00.00028: Synthesis and characterization of molybdenum carbonitride nanoplates Samantha Stapf, David E Sanchez, Alexander J Sredenschek, Mauricio Terrones Molybdenum carbide (MoC/Mo2C) in bulk is chemically stable, corrosion resistant, metallic, and superconducting. Due to advancements in the nanotechnology field and synthesis procedures, single-crystal MoC/Mo2C in a nanoplate morphology has been fabricated and retains the properties of bulk down to a few nanometers in thickness. Further tuning the electronic properties could potentially be achieved by alloying with nitrogen through ammonolysis. Nonetheless, a structural characterization tied to the ammonolysis treatment must be undertaken to obtain single crystalline molybdenum carbonitride (MoCN). We implemented a two-step procedure: MoC/Mo2C was synthesized by chemical vapor deposition then converted to MoCN by ammonolysis, with varied temperature and time to study the conversion. Scanning electron microscopy was used to analyze the morphology of the nanoplates. Selected area electron diffraction and X-ray diffraction were used to evaluate the crystallinity. We established that high temperatures and long durations cause rapid diffusion of nitrogen, leading to a polycrystalline structure. Future work includes optimizing the ammonolysis treatment and characterizing the electronic properties of single-crystal MoCN. |
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G00.00029: Chemical Vapor Deposition of Rhenium Disulfide Nanoflowers: Effects of Water-Vapor, Substrate Preparation and Post-Growth Treatments. Sarai Vega, Humberto Rodriguez Gutierrez Rhenium Disulfide is a layered Transition Metal Dichalcogenide (TMD) that exhibits a direct bandgap and potential applications in photosensors, catalysis, and biomedicine. In this work, we study the role of water-vapor during the growth of Rhenium Disulfide via chemical vapor deposition (CVD); rhenium pentachloride and sulfur powder were used as the metal and chalcogen sources, respectively. The introduction of water-vapor during the CVD growth increases the yield and the crystal quality of the samples which resulted in high-density free-standing ReS2 nanoflowers. The presence of small amounts of chalcogen powder on the substrates, before the growth, also increases the yield via creation of additional nucleation centers. Raman and Photoluminescence (PL) spectroscopies were used to characterize the samples, and a laser power-dependent study is presented. After growth, the ReS2 nanoflowers were exposed to a UV treatment in different reactive atmospheres to passivate and/or chemically dope ReS2. The effect of the post-growth treatments on the PL yield as a function of number of layers is also discussed in this work. |
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G00.00030: Polarization Sensitive Low Frequency Raman and Coherent Raman Spectrum of Crystals Lavender Allen, Laszlo J Ujj We have measured the polarization-sensitive vibrational phonon spectra of a single crystal of cubic symmetry, Bismuth Germanate with the chemical formula Bi3Ge4O12 (BGO). We observed the phonon modes connected to the symmetry species of the crystal. First, the polarization sensitive Raman spectra were measured at specific configurations allowing us to distinguish and associate band frequencies to the A, E and F modes in accordance with group theory. We used and modified the laser system available at the laser spectroscopy lab at the University of West Florida to obtain the proper polarizations and excitation conditions necessary to isolate the modes. |
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G00.00031: Numerical Calculations of Atomic Excitation with Nanosecond Pulses Rena Beban We are conducting numerical calculations of atomic excitation probabilities with nanosecond and sub-nanosecond pulses of laser light. We intend to compare our results to real-time fluorescence measurements of Rb atoms taken in the lab. |
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G00.00032: Spectroscopic study of the 4f76s2 8So7/2 - 4f7 (8So) 6s6p (1Po) 8P9/2,7/2,5/2, transitions in neutral europium-151 and europium-153: absolute frequency and hyperfine structure. Maria-Teresa Herd, Will D Williams, Gaven Cannon, Chitose Maruko We report on spectroscopic measurements on the transition in neutral europium-151 and europium-15313 at 459.4 nm. The center of gravity frequencies for the 151 and 153 isotopes for the 4f76s2 8So7/2 - 4f7 (8So) 6s6p (1Po) 8P9/2 transition were found to be 652,389,757.16(34) MHz and 652,386,593.2(5) MHz, respectively. The hyperfine coefficients for the 6??6??(1 ???) 8 ??9/2 state were found to be A(151) =16 -228.84(2) MHz, B(151)= 226.9(5) MHz and A(153) = -101.87(6) MHz, B(153)= 575.4(1.5)17 MHz, which all agree with previously published results except for A(153), which shows a small discrepancy. The isotope shift is found to be 3,163.8(6) MHz, which also has a discrepancy with previously published results. Center of gravity frequencies for the 4f76s2 8So7/2 - 4f7 (8So) 6s6p (1Po) 8P7/2, and 4f76s2 8So7/2 - 4f7 (8So) 6s6p (1Po) 8P5/2 transitions will also be reported. |
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G00.00033: Simulating the Classical Stern-Gerlach Effect Lana Flanigan, Emma Z Kurth, Nicholas J Harmon Predictions of the Stern-Gerlach effect with classical magnetic moments have been commonly in error due to overlooking the constraints Maxwell's equations on a non-uniform magnetic field [1]. In addition, the role of classical spin precession in such an experiment has been debated [2,3]. For the first time, to the best of our knowledge, we perform simulations of the Stern-Gerlach effect for ensembles of randomly oriented classical magnetic moments passing through a region of inhomogeneous magnetic field. We also explore the Stern-Gerlach deflections for polarized classical spins. After simulating trajectories in simple fields, we model a more realistic scenario where the gradients are generated by two magnets. Our results provide clarity to the dialogue in Refs [2,3]. |
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G00.00034: Crystal Structure Determination Through X-Ray Diffraction Aydan P Gibbs Magneto Optic Kerr Effect experiments require that your samples be aligned with the induced magnetic field within a certain degree of accuracy. Using x-ray diffraction you can analyze the orientation of crystals. Taking multiple scans of a Co3Sn2S2 sample from 20 degrees to 80 degrees of theta and rotating the sample by 15 degrees of phi between each scan and stacking that data into a 2-D histogram, we can determine how the unit cells are oriented within the sample. We then represent this data in a new form of visual aid called a Langelund Diagram. |
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G00.00035: Controlling the polarization transmitted through an electro-optic modulator in a laser feedback interferometer Avery A Gilson, Ben Ovryn High precision optical interferometry demands single polarization laser beams. This requires the implementation of polarization elements with high extinction ratios. For many applictions, commerially available Glan Thompson polarizers with extinctions ratios greater than 100000:1 are sufficient. Additionally, it is often critical to characterize the orientation of the polarization of the light incident on a sample and to control the orientation as the beam transmits through optical elements. The phase-shifted laser feedback interferometer implements a broadband electro-optic modulator to reliably introduce controlled phase shifts so as to determine changes in optical path length and fringe visibility. In order to produce a controller phase modulation without a concominant amplitude modulation, it is critical to control the orientation of the linear polarization as it enters the modulator. The implementation of the phase-shifted laser feedback interferometer uses a HeNe laser (with extinction 500:1) and an electro-optic modulator (New Focus, 4002) modulated by a high-voltage operational amplifier (New Focus, 3211). In order to calibrate the polarization, a Berek compensator (New Focus, 5540) is used to introduce a controlled retardance. When the Berek compensator is used in conjunction with wave plates, it is possible to implement a series of measurements to determine all four components of the Stokes vector. This approach can be used to completely characterize how an optical element alters the incident polarization. |
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G00.00036: Einstein Beams for Free-space Optical Communications Kiyan Hocek, Tarik Cigeroglu, Valeria Rodríguez-Fajardo, Enrique J Galvez The ability to transfer information at high speeds across free-space is important to the modern world. We present a proof of concept method, using non-diffracting self-healing Einstein Beams, inspired by gravitational lensing, to encode information for free-space communication. We do this by adding different topological charges of OAM to the beam to create unbounded orthogonal states. We can improve the channel capacity by multiplexing between each of these states. Then we add a periodic time-dependent rotation to allow for computionally efficient decoding by the receiver. Aditionally, the self-healing properties make these beams a good candidate for high-bandwidth optical communications. If there is an obstructing object is between the source and receiver the beam will reform with propagation and there will be less information loss with this method. |
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G00.00037: Molecular Dynamics Simulation of Thin Films Grown by Physical Vapor Deposition Rosalba A Huerta, Weiling Xia, Owen C Bellevage, Valentine Novosad, Benjamin Church We computationally investigate the effect of film growth parameters on the deposition of thin films by Molecular Dynamics (MD). Our team utilizes Large-scale Atomic/Molecular Massively Parallel Simulator software, where we simulate the vapor deposition of dielectric and conductive materials on the surface of a silicon substrate. By computing the gradient of the potential energy using a classical force field, we can monitor the formation of film and validate the accuracy of the deposition process. In the case of metallic and dielectric materials, we can compare the simulated physical properties to the experimental data of surface morphology. This work improves our understanding of the interatomic interactions, such as lattice formation of the target atoms, to adjust deposition parameters and achieve desired mechanical properties. Further analysis of the correlation between simulations and experimentally grown films will allow for better application in layered microelectromechanical systems (MEMS). |
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G00.00038: Locking multiple lasers to a single optical cavity Matt Grau, Evan J Johnson One of the biggest unsolved problems in modern physics is the excess amount of matter compared to antimatter that exists in the universe. Charge parity (CP) symmetry violation could explain this imbalance, but there are not enough sources of CP violation to explain the size of the imbalance we observe. The nuclear magnetic quadrupole moment (nMQM) experiment at ODU seeks to perform precision measurements on Lutetium ions to look for sources of CP symmetry violation beyond what has been found in high-energy particle physics experiments. This experiment requires multiple lasers for laser-cooling and atomic state manipulation, which we must lock to a reference cavity. Locking multiple lasers to a single cavity can result in unwanted correlations between the lasers as thermal effects cause their feedback loops to interfere. For this project, we will lock multiple lasers to one cavity and characterize and then mitigate the amount of interference in this system. |
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G00.00039: Development of a database of Rb Rydberg atom properties in support of demonstrating an EIT-based quantum antenna Lee E Harrell, William Kaiser, Nathon L Segovia, Samantha C Damonte, Kirk A Ingold, David O Kashinski, Brian C Holloway Quantum Information Science & Technologies (QIST) is a topic of national priority. QIST has the potential to enable a new generation of transformative sensors similar to the transformative impact that the Global Positioning System (GPS), nuclear spin control for magnetic resonance imaging (MRI), and atomic clocks had in the last century. Researchers in the Photonics Researcher Center's Atomic, Molecular, and Optical Physics program (PRC-AMO) at the United States Military Academy are working to establish an education-centered QIST research laboratory with an initial focus on Quantum Sensors. Our immediate research objective is the demonstration of an operational Rydberg-atom (rubidium-based) Radio Frequency (RF) antenna capable of quantitative E-field meteorology, achieved through two parallel lines of effort: developing the theoretical model of a 4-level ladder system coupled with noise and the sharp absorption features in the electromagnetic induced transparency (EIT) spectra, and the provisioning of the QIST laboratory, to include all necessary optical accessories and lasers. This poster presents our progress constructing a database of Rb Rydberg atom properties in support of demonstrating an EIT-based quantum antenna. |
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G00.00040: Undergraduate Custom Designed Cost Effective IR Optical Tweezer Set Up fo DNA Applications Dylan Kirkeby Our research team, ISLAND CURE, is a multidisciplinary team of professors and undergraduate students with the goal to design and build instruments to make biological measurements on a limited budget. One of the apparatuses we are designing, is optical tweezers, which are a Nobel Prize-winning technology capable of trapping microscopic and sub-microscopic particles using a laser beam. Using a 1064 nm beam, we will trap a single strand of DNA using beads and this will enable us to exert minute forces upon the DNA. This experiment will give us a better understanding of the forces on damaged DNA; specifically, the damages that lead to mutations and cancer. With this knowledge our goal is to be able to provide insight into mutagenesis and cancer development, and ideally how to treat and prevent them. This presentation will update on the present development of our cost effective, custom IR tweezers. |
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G00.00041: Computational Exploration of Anti-Reflective Nanostructures Ganesh Petterson, Catherine Jahncke, Wataru Nakagawa, Jordan Baker Anti-reflective (AR) coatings and structures are a key part of many optical systems, providing increased transmission efficiency and reducing issues related to back-reflection and unwanted interference. However, the theory behind these devices means they often function best at specific wavelengths and incidence angles, leading to difficulties when reflection needs to be minimized over a broadband spectrum or wide angular range. This project uses the GD-Calc MATLAB package to computationally explore the design of AR nanostructures, periodic patterns of sub-wavelength structures designed to create a gradient in the effective refractive index. Baseline construction parameters are determined from previous work in the literature, manufacturing feasibility is considered when determining final structure parameters, and structure performance is evaluated based on overall transmittance as well as sensitivity to small parameter variations. We present the results of our exploration of structures such as cones, cylinders, and pyramids with manufacturing parameters optimized for 1550 nm light under a variety of incidence angles. |
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G00.00042: The effect of Duschinsky rotation on Femtosecond Coherence Spectra Mihail Popa, Daniel B Turner, Paul C Arpin Ultra-short laser pulses can coherently excite molecular vibrations, which appear as oscillations in the signal of time-resolved spectroscopy measurements. In a transient-absorption spectroscopy measurement, there are typically several normal mode vibrations that contribute to the oscillations, and the amplitude and phase of each oscillation varies as a function of probe frequency. Femtosecond Coherence Spectroscopy (FCS) resolves the amplitude of the oscillations as a function of probe frequency and oscillation frequency creating mode specific amplitude profiles. Prior work attempted to fit FCS profiles to a variety of one-dimensional models and showed promising results as a method to determine photo-physical parameters of laser dyes, but was unable to reproduce certain features in the data for physically relevant parameter values [1 - 2]. In particular the single-mode model could not reproduce the relative peak heights observed in the measured profiles. Here we show that a two-mode model incorporating Duschinsky rotation is able to reproduce the relative peak heights and is a promising approach to fit FCS profiles [3]. |
Author not Attending |
G00.00043: Predicting Lattice Orientation of Lithium Niobate using Machine Learning aided Raman Spectroscopy Martin H Sipowicz, Collin Barker, Volkmar G Dierolf, Keith Veenhuizen, Himanshu Jain, Evan Musterman Due to its nonlinear, electro-optical properties, Lithium Niobate (LiNbO3) is a widely used materials system for integrated optics. We previously developed a technique in which single crystal LiNbO3 is produced within a glass using femtosecond laser heating. In this process, the orientation of the crystal is of utmost importance to achieve desired functionalities. For this reason, understanding how to measure and alter crystal orientation are crucial. The current method to determine crystal orientations, Electron Backscatter Diffraction (EBSD), requires sample preparation that is time-consuming and partially destroys the crystals under study. Therefore, this method is not practical to investigate large numbers of samples while maintaining their functionality. Raman Spectroscopy is noninvasive; in principle, it can determine crystal orientation although the assignment includes more noise. We employed a K Nearest Neighbors machine learning algorithm to better sort through this noise. This model used orientation data from EBSD to teach the computer orientation behaviors in Raman spectra. Subsequently, we successfully determined crystal orientations, using Raman spectra of crystals embedded within a glass sample, as well as shifts in those orientations. |
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G00.00044: Developing an Antimatter Gravity Interferometer Jacob Thomas The assumption that the effects of gravity on antimatter and matter are equivalent has permeated throughout almost all of modern physical theory and experiment. However, no direct observation of this effect from gravity has been made on a particle in freefall. A muonium beam diffracting through a series of gratings has proven to be a suitable method for recording such freefall. Simulating this with the best current understanding of diffraction and interferometry is vital in determining this antimatter-gravity relationship, since a physical construction requires a picometer-precise atom interferometer and muonium beam. The development of these simulations has both demonstrated the relative feasibility of experimentation and brought to question the viability in applying certain physical modeling and simulation methods. |
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G00.00045: SARS-CoV-2 Quantum Sensing Using NV Centers in Nanodiamonds Temazulu S Zulu
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G00.00046: Fluorescence studies of small heat shock protein oligomerization David Arnett, Parker Fryar, Isaiah Gritters, Jackson Hofland Small heat shock proteins (sHSPs) act as chaperone molecules, capable of preventing the unfolding and subsequent irreversible aggregation of target proteins. Regulation of sHSP chaperone function is tied to their oligomeric aggregation state, which ranges from small but active monomers and dimers to large, but mostly dormant, complexes consisting of 24 or more subunits. This range of complexes, or "oligomeric equilibrium", is influenced by environmental factors like temperature or pH. The project described in this poster uses various fluorescence methods to investigate the oligomeric equilibrium for the protein MjHSP16.5. Complexes formed from fluorescently labelled MjHSP16.5 samples are characterized individually through confocal microscopy. Samples that have been exposed to low pH and/or high temperature fluoresce less than untampered complexes, consistent with a shift toward smaller complexes in response to extreme conditions. The results of this experiment will be presented and compared with partnering experiments that examine MjHSP16.5 samples in dilute solutions through fluorescence correlation spectroscopy or in concentrated solutions though bulk FRET measurements. |
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G00.00047: Potential Causes of Electrical Responses due to Musical Influences during In vivo and In vitro experiments. Taniya S Ballard, Zaria A Dillahunt, Krislynn N Hawthorne, Myron D Brown, Tennille D Presley Music has been proven to elicit autonomic responses in human cells such as cell viability, cell motility, and skin conductivity. There is currently little research indicating the latent reason behind music eliciting electrical activity responses. Our study aims to determine how various genres of music impact the electrical activity in the body. We hypothesize that electrical activity will be affected within the vivo experiments of human participants based on genre, tempo, emotions and familiarity, and within experiments of bovine brain artery endothelial cells (BBAECs) based on genre and tempo. We used a musical playlist consisting of three genres: gospel, rock, and classical. Each song was played for 120 seconds, alternating with a 120 seconds quiet period at the beginning and end. For in vivo experiments, electrical activity was analyzed via skin conductivity using a Q-S222 galvanic skin response (GSR) sensor. For in vitro experiments electrical conductivity is analyzed via cell viability and cell proliferation. While rock exhibited the highest GSR, the study is ongoing and the results are being analyzed. Understanding this information, we can elucidate how music affects certain processes within the body to elicit musical responses such as brain activity and cerebral brain flow. |
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G00.00048: Pausing by E. Coli RNA Polymerase at LacI and EcoRI Protein Roadblocks Allison G Cartee, Jin Qian, Irina Artsimovich, Wenxuan Xu, Derrica McCalla, David Dunlap, Laura Finzi The synthesis of messenger ribonucleic acid (mRNA) from template deoxynucleic acid (DNA) by RNA polymerase (RNAP) decodes genetic information in all forms of life. In vitro, motor enzyme RNAP translocates at up to 20-25 base pairs per second, but forces and transcription factors can modulate activity and intrinsic pausing, critical for regulation. Previous studies suggest RNAP may backtrack after intrinsic pausing, which may prolong the inactive state, upon encountering a physical obstacle along the template DNA. It is uncertain whether RNAP actively disperses a roadblock or passively waits for it to dissociate. DNA binding proteins LacI and EcoRI were used as site-specific roadblocks, and E. Coli RNAP pause times were measured as a function of forces opposing or assisting RNAP translocation via magnetic tweezers. Pauses were also measured in the presence of GreA, a protein that rescues backtracked RNAPs by cleaving nascent RNA backed up into the catalytic site. Regardless of magnitude, forces opposing RNAP at LacI increased average pause durations compared to assisting forces. However, including GreA eliminated this difference. Moreover, the addition of GreA rescued complexes stalled indefinitely at EcoRI. Overall, backtracking by transcription elongation complexes extends pauses at EcoRI and LacI roadblocks unless GreA is present, but these two roadblocks must dissociate before RNAP can proceed. Our biomechanical measurements elucidate how forces on the genome affect RNAP behavior at roadblocks. |
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G00.00049: Insights into the Cardiac Effect of Music on the Electrical Activity of the Body Zaria A Dillahunt, Taniya S Ballard, Krislynnn N Hawthorne, Myron D Brown, Tennille D Presley Universally, music tends to exhibit an emotional response on the body. A particular beat or rhythm may modify one's heart rate or blood pressure; however, the distinct way in which music affects the cardiovascular properties of the body tends to vary. In this study, we address the impact of different musical genres on both skin conductivity of participants and cell viability of Human Aortic Endothelial Cells (HAoECs). We hypothesize that both skin conductivity and HAoECs viability will be affected based on genre and tempo. A musical playlist was curated consisting of three musical genres: R&B, Country, and Hip Hop. Each genre had three songs which were played for 120 seconds, followed by a period of silence for 120 seconds. The HAoECs were exposed to music daily for a fixed time and cell viability was determined. Each participant's electrical response was measured through skin conductivity using a Q-S222 galvanic skin response (GSR) sensor. The combined results provide insight into the body's electrical response to music. The R&B playlist has the highest tempo and tends to exhibit the greatest response; however, the research is ongoing and the data is being analyzed. Upon completion, we can determine the cardiac effect of musical exposure within the body. |
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G00.00050: Hollow hair and how its structure helps big game animals thermoregulate Taylor Millett The Pronghorn antelope is an animal known to have hollow hair strands among hunters and conservationists yet no one seems to know what it actually looks like on the inside. In this study, we examined what a hollow hair strand looks like under a microscope and how it helps with an animal’s thermoregulation. Thermoregulation is the ability to regulate body temperature within a livable range even when external temperatures fluctuate. We studied animals like Mule deer, Rocky Mountain elk, and Pronghorn antelope, as well as other big game animals, as they exhibit this trait in a unique manner. These animals have an adaptation more commonly known as a summer coat and a winter coat. Using a scanning electron microscope, we measured and compared an animal's winter coat and summer coat to indicate why an animal can regulate body temperature through hot summers and cold winters. These coats of fur/hair change in thickness and length with the change of seasons. Under the microscope, we identified the different topography of the inner structure of a single hair strand. We found that the inner structure has hollow pockets in the winter coats of these animals. These pockets varied in diameter ranging from 90 micrometers to 20 micrometers depending on the animal analyzed. |
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G00.00051: Investigation of the use of sodium dodecyl sulfate for reducing leakage of bovine serum albumin from ethyl cellulose microcapsules Nathaniel H O, Anil D'Mello, Kyle Yetsko, Stephanie Levy Phenylketonuria (PKU) is an inborn metabolic disorder where an inability to metabolize phenylalanine (Phe) results in its toxic accumulation in blood and brain. Our laboratory proposes using microencapsulated phenylalanine ammonia lyase (PAL) as an oral therapy for managing PKU. Encapsulated in semipermeable, non-digestible ethylcellulose (EC), PAL will metabolize Phe in the gastrointestinal tract and lower Phe absorption . Using bovine serum albumin (BSA) as a model protein we are determining the best method for manufacturing microcapsules. We investigated the effectiveness of spray drying a BSA-EC suspension and found rapid leakage of protein, which is undesirable. We then complexed BSA with surfactants, hypothesizing that their amphipathic nature would increase hydrophilic BSA's affinity for the hydrophobic EC capsule. These microcapsules also exhibited rapid protein leakage. We suggest that the differences in viscosities and spray radii of the solid and oil phases prevented proper encapsulation of BSA via spray drying. We are now investigating solvent evaporation from a solid/oil/water emulsion: first with BSA alone, then with BSA-surfactant complexes. We expect the slower precipitation of EC around BSA particles to produce more complete encapsulation and reduce leakage. |
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G00.00052: Gel vs. Plaque Formation during Self-assembly of Amyloid Fibrils Laura M Tirado, Martin Muschol Self-assembly of proteins into amyloid fibrils plays a key role in both functional biological responses and pathogenic disorders, which include Alzheimer’s disease and type II diabetes. Much effort has focused on the formation of individual fibrils and oligomeric intermediates formed during fibril growth. However, for understanding the pathological effects of amyloid fibrils as well as for their application in functional biomaterials, it is equally important to understand the types of fibrillar suprastructures they tend to form. Using pre-formed amyloid fibrils, we investigated their self-assembly into larger supramolecular fibril networks as function of charge screening and solution pH. At acidic pH, increasing charge screening caused lysozyme amyloid to assemble into disordered gel clusters. In contrast, fibril self-assembly at neutral pH induced rapid formation of compact, nearly two-dimensional fibril sheets. The latter displayed localized birefringence considered hallmarks of amyloid plaques in vivo. Our observations suggest that the pH-dependent charge distribution of the monomers within the fibrils plays a significant role in fibril self-assembly. This provides an adjustable parameter for modulating the self-assembly behavior of amyloid fibrils into larger suprstructures. |
Author not Attending |
G00.00053: Agent-based Model to Explore the Stability of Social Insect Symbiosis Jason Wong Symbiosis is prevalent throughout biology, including between social insects. One such instance is the Sceptobius lativentris rove beetle evolving to coexist stably with Liometopum occidentale using acquired cuticular hydrocarbon (CHC) mimicry, with no known instances of a beetle leaving its colony and assimilating into nearby ant colonies. With that in mind, how do beetles and ants interact to maintain this stable coexistence? To better understand this, we employed an agent based model of beetle ant interactions to explore how their dynamics limit the beetle to within its host colony. We found that various negative feedback loops exist. For example, an extremely low host ant population allows colony crossings to occur, but leaves beetles vulnerable to neighbor hostility, making crossings less likely overall. Furthermore, crossings can occur with extremely close neighboring colonies, but the increased fighting also makes the arrangement unstable and unlikely. The conflicting effects of several parameters create a stable beetle-ant system and allow for long term symbiotic evolution. We believe that these results are a crucial clue in understanding insect evolution and the dynamics of insect populations in general. |
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G00.00054: Microwave-Transparent Infrared Filters for Superconducting Qubits Richard Dong, Evangelos Vlachos, Eli Levenson-Falk Infrared light traveling down coaxial cables can impact a superconducting quantum device, generating quasiparticle excitations and causing decoherence in superconducting qubits. Typically, this infrared radiation is suppressed by coaxial filters with a lossy Eccosorb dielectric. However, Eccosorb also strongly attenuates wanted microwave signals. We have investigated methods to suppress infrared radiation without unduly attenuating microwave signals. We present experimental and numerical results for filters based on alternative materials (including STYCAST 2850FT and borosilicate glass), resonant effects, and alternative geometries. |
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G00.00055: The Effect of Neutrino Flavor Oscillations on The Supernova Early Warning Pypeline (SNEWPY) Anne Graf The observation of the next supernova in our Galaxy will greatly advance our understanding of how massive stars die. The value of an early supernova alert cannot be overstated because it is a once-in-a-generation event. The earliest indication of the explosion is the arrival of the neutrino burst which will lead to a simultaneous increase of the number of neutrino events in all the neutrino detectors around the globe. In order to prepare for such a burst, detectors first have to know what that looks like. Enter SNEWPY. The SNEWPY code is a data pipeline that connects supernova simulation data with the SNOwGLoBES code, which computes event rates for different interaction types in neutrino detectors, then collates the data into observable channels. Using this pipeline, we can explore the landscape of different types of supernovae, thus enhancing the supernova early warning system. As neutrinos travel to Earth, they undergo flavor oscillations modulated by their environment. I will explain how SNEWPY enhances the use of SNOwGLoBES, and discuss the upgrade to SNEWPY that will involve new time and energy dependent flavor transformations. |
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G00.00056: Quantum Engineering in the Undergraduate Laboratory: Quantum Foundations and Applications of Quantum Information Science Robert Hare The applications of quantum mechanics to computing, communication, and sensing may constitute a revolution in technology. Providing exposure to applied quantum engineering in the undergraduate is critical to ensuring the development of the "quantum workforce." The first phase of this project designs, builds, and characterizes the first entangled photon source available to undergraduates at the U.S. Naval Academy. Entanglement is a critical aspect of quantum technology, but entangled systems behave in strange ways that are counterintuitive to our classical view of the world. This project seeks to analyze its behavior and the concept of local realism through experimental verification, followed by utilizing these properties for various applications such as quantum cryptography. |
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G00.00057: An application of quantum machine learning for inter-case predictive process monitoring Stefan Hill, David P Fitzek, Carl Corea, Patrick Delfmann Today, complex business decisions are based on big data. The omnipresent digital infrastructure allows to log events and extract visual representations from complex business processes. In that manner, it is possible to track business cases and convoluted interactions in real-time. Furthermore, under the umbrella of Predictive Process Monitoring (PPM), a number of machine learning techniques emerged that aims to forecast future behaviour of a business case such as next activities or remaining time. Processes occur everywhere and applications for PPM can be found in domains ranging from logistics to energy management to hospitals. However, often, the outcome of a single process instance does not solely depend on its history rather than the state of other instances that are executed in the same time. Likewise, feature vectors for accurate recommendations grow arbitrarily for a huge amount of process instances. |
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G00.00058: Experimental Characterization of a Modular Dissipator for On-Demand Cavity Cooling Jocelyn Liu, Haimeng Zhang, Darian M Hartsell, Clark Miyamoto, Vivek Maurya, Eli Levenson-Falk In superconducting qubits, spurious thermal photons in readout cavities are a major source of dephasing error. Properly thermalizing these cavities often involves putting large amounts of attenuation on the microwave lines, suppressing the speed of operations, causing excess cryostat heating, and reducing readout fidelity. We use an alternative approach where dissipation is introduced on-demand to cool a cavity. We have designed and fabricated a hybrid device consisting of a fixed frequency logical qubit with a readout cavity parametrically coupled to a lossy flux-tunable "dissipator," which can induce the removal of thermal photons from the cavity into the environment on-demand. Theoretical and numerical results have already validated the efficacy of this driven dissipative cooling. In this presentation, we show measurement techniques for characterizing the effectiveness of this device, and discuss the experimental results demonstrating the effects of dissipative cooling on the logical qubit in this design. |
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G00.00059: Fabrication of Tapered Optical Fibers for Free-Space Access Microcavities Georgia Eirini Mandopoulou, Ralf Riedinger, Lasse Irrgang Progress in cavity quantum electrodynamics based platforms for quantum networks is reliant on the development of easily accessible microcavities with high-cooperativity and flexible designs. To realize efficient scalable quantum information settings and to enable couplings of multiple atomic qubits, the cavities employed should be fiber-coupled and should enable a low-noise environment, while facilitating maximal optical access to the atoms trapped in the center. To this end, this thesis explores methods for the development of tapered optical fibers suitable for integrated cavity designs with optimal free-space access. The tapered fibers explored in this work are fabricated with a chemical etching procedure employing the vapor phase of hydrofluoric acid (HF). The tapering process is anteceded with the curing of a photosensitive polymer at the tip of the fiber, aiming to preserve the integrity of the fiber during the etching process by creating an HF-resistant protective cap. The conducted experiments show, that although the fabricated protective coatings are not attacked during the etching, they do not demonstrate sufficient protective properties. Further, it is concluded that the HF vapor phase can successfully lead to the formation of tapered fiber profiles, albeit in a non-reproducible manner. As a result, the promising but not consistently reproducible experimental findings highlight the need for an enhanced control over several variables in order to fine-tune and optimize the etching process. |
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G00.00060: Developing a library of modular superconducting qubit components for rapid device design Clark Miyamoto As superconducting qubit fabrication advances and devices become increasingly complex, turnaround times for device screenings grow longer and longer and design tolerances become tighter. It is now necessary to have accurate simulations of device performance before fabrication. The standard method uses 3D electromagnetic solvers such as Ansys’s HFSS / Q3D to determine device parameters. However, this can be a major bottleneck in the design process, and can sometimes yield inaccurate results. One potential solution is to create a design library of compact, modularized, and accurately-simulated components that can be combined in a larger design without expensive full chip simulation. We present a workflow combining Ansys EM solvers, parallel high-performance computing, and analytic calculations in order to develop an open-source library of superconducting quantum device components. Our library is an extension of IBM’s Qiskit Metal package. As a demonstration, we present a device incorporating a transmon qubit, a measurement cavity, and a lossy parametric coupler. |
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G00.00061: Determination of Elevation with Muon Flux Measurements Clara L Sobery, Sabrina L Sobery, Richard Lombardini Clara Sobery, Sabrina Sobery, and Dr. Richard Lombardini |
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G00.00062: Exploring the adsorption mechanism of a CO2 molecule in graphene and graphene oxide structures employing DFT Erica Valencia Gomez, J. J. Prias-Barragan, Cristian Villa Zabala In this research, we present a theoretical interpretation of the adsorption mechanism of a CO2 molecule in graphene and graphene oxide (GO) structures, which were previously proposed, via DFT with hybrid functional B3LYP, obtaining the global reactivity indexes, the NCI and MEPs which were studied; finding, the formation of hydroxyl bridges; also, the adsorption of the CO2 molecule by a physisorption mechanism and a decrement on the global reactivity. These results suggest that GO is an excellent candidate material to capture CO2 from the environment. |
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G00.00063: Collective proton transport in polyphosphoric acid William D Brackett, Catalin Gainaru, Ivan Popov, Alexei P Sokolov One current goal of modern science is to rationalize and utterly exploit the factors governing proton conductivity for the next generation of energy storage technologies, including fuel cells. The so-called Grotthuss mechanism is generally considered to promote most efficient proton conductivity, implying cooperative, chain-like transfer of protons along the hydrogen-bonded networks of host molecules. However, such constructive type of collective dynamics has not been demonstrated experimentally so far. Employing dielectric spectroscopy, quasielastic neutron scattering, and ab initio molecular dynamic simulations we recently reported a direct experimental observation of proton transfer between the molecules of phosphoric acid. Intriguingly, although our analysis confirmed the existence of correlations between the proton jumps in this material, these lead to effective loops-like charge backflows which are reducing its conductivity, in contrast to the expectation for a Grotthuss mechanism. The present work will investigate how proton transport and its relationship with the structural rearrangements are influenced by the covalent bonding of phosphoric acid molecules. In particular, using polyphosphoric acid as a model system, we will discuss the possibility of tailoring a desired Grotthuss-like type of cooperativity for charge transport via a chain packing of the structural constituents in proton conducting materials. |
Author not Attending |
G00.00064: Examining and Defining the Structure of Saturn’s B-ring Madisyn Brooks Beta Centauri is one of the brightest stars observed by Cassini’s Ultraviolet Imaging Spectrograph (UVIS) stellar occultation experiment. 15 occultation traces of Beta Centauri were performed with a high elevation angle above the Saturn ring plane. Combining the high elevation and strong stellar signal from these occultations allows for strong constraints to be made on the transparency of high optical depth regions. The highest optical depth regions are located in Saturn’s B-ring, and specifically the B2 region of this ring. We are examining the high optical depth regions of Saturn’s B-ring to look for significant structure across the extent of the ring plane and to catalog these changes for further analysis. These regions are also defined by non-repeating, narrow regions of translucence where the observed transparency fluctuates from less than 1% to 20%. These features are called “phantoms” and are scattered throughout the otherwise opaque regions of Saturn’s B-ring. We will describe the characteristics and distribution of both the opaque regions and their accompanying phantoms. |
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G00.00065: Using Neural Networks to Constrain Cosmology from Neutral Hydrogen Distributions Rajib Chowdhury Upcoming measurements of the redshifted 21-cm line are poised to make the first large breakthroughs in the reionization era. By directly imaging neutral hydrogen, key constraints can be gleaned for cosmology and astrophysics, specifically ΛCDM parameters and astrophysical parameters. The amount of data produced from these observations is expected to be immense and optimal methods need to be developed in order to extract the relevant cosmological information. Here we neutral hydrogen data from the astrophysical simulations, SIMBA and IllustrisTNG, to train neural networks to perform likelihood-free inference on ΛCDM parameters. Power spectra of the simulation data is used as a summary statistic and used as training data. We examine how the information at smaller scales is related to the underlying cosmology and astrophysical models. Robustness of our method is examined by testing against different simulation techniques. |
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G00.00066: Plasma Wakefield Accelerators, and Solutions to Compactness and Efficiency Morgan L Cole Plasma wakefield acceleration presents important solutions to the emerging challenges of modern particle accelerators, and thus has the potential to shape the future of accelerator technology in our society. I will be presenting my work on plasma wakefield accelerators during my undergraduate internships, including my work on the adiabatic focusing response of low density plasmas at CERN's Advanced Proton Driven Plasma Wakefield Accelerator Experiment (AWAKE), as well as my work on nonlinear optics and plasma mirrors at the Lawrence Berkeley National Laboratory. The technical concepts that I have pursued (and will investigate further), could become critical tools in enabling not only compactness in accelerator applications, but also doing so in an energy-efficient manner. |
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G00.00067: Multiphysics Simulation of Thermoelectric material (GST225) Dania T Collie, Darnell Coicous, ostonya thomas, Krystin Ferguson, Ming Yin, Godwin Mbamalu Thermoelectric (TE) generators are non-mechanical low maintenance systems that convert heat directly into electricity with essentially no or little side effects or pollution, additionally they are extremely compact. The germanium based compounds, GeSbTe (GST) and other ternary systems hold the potential as high efficiency thermoelectric materials. It is very important to study the thermal and electrical properties of materials in order to fine new thermoelectric materials. COMSOL Multiphysics is comprehensive simulation software. It allows calculations of electrical and thermal profiles in different geometries with temperature dependent material properties. We use COMSOL to find out the temperature distribution in GST225 sample. The simulation results of other properties of GST225 will be presented. |
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G00.00068: Uses of Stereolithography Additive Manufacturing in Cryogenic Heat Capacity Measurements Donovan Donald, Angel Joaquin Perez Linde, Rosa E Cardenas Affordable additive manufacturing stereolithography devices or 3D printers have been used to produce parts of a specific heat probe that fit in an enclosed insert inside a variable temperature insert of a cryogen free magnet, ranging in temperatures from 2 to 300 K and magnetic fields from 0 to 9.4 T. Specific heat measurement results obtained with lanthanide-based materials in these ranges are presented are discussed. |
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G00.00069: Mapping Magnetic Fields with Near-Field Scanning Optical Microscopy Raphael J Ettinger-Finley, Juan M Merlo-Ramirez We present the implementation of a near-field scanning optical microscope (NSOM) to observe |
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G00.00070: Characterization of Seiche in a Relatively Small Artificial Basin Hugh A Gallagher A seiche is effectively a standing wave that forms in the water surface of an enclosed (or partially enclosed) basin such as a lake. The frequency of seiche oscillations is primarily determined by the geometric characteristics of the enclosed basin. In this poster, we describe the observation and characterization of seiche occurring in artificial basins of simple geometry. Additionally, we examine similarities and differences between seiche that are driven by a temporal variation of the water surface and those excited by spatial variation of the surface. Using an ultrasonic sensor, the surface water height at a specific location was measured over time during the occurrence of seiche in an artificial basin, namely a rectangular tub. A discrete Fourier analysis applied to the surface height time series is used to determine the frequencies of the seiche modes present. Using these observations, we construct dispersion relationships for temporally and spatially excited seiche at three different depths. The dispersion relationships for the temporally driven seiche are in strong agreement with the general surface gravity wave dispersion relationship. However, the dispersion relationships for seiche produced by a spatial variation in the surface position are not well modelled by the general surface gravity wave dispersion relationship. |
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G00.00071: Modeling and Constructing an Efficient Railgun Austin N Galli By using Lorenz force and Biot Savart's law to mathematically model the parameters of a railgun, an optimally efficient system can be designed. Multiple models were constructed with varied parameters such as projectile weight, rail materials, and capacitance to evaluate how the system was affected and how accurately the equations represent the system. The parameters remained within reasonable limits to ensure an optimal balance between cost-effectiveness and accessibility. The design is particularly intended for students and educators, and yields a simulation able to model their hypothetical system with a set of accessible equations. |
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G00.00072: Color-Magnitude Diagrams of Low-Mass Dwarfs in the Sagitta M71 (NGC 6838) Globular Cluster Cedar Garcia We can classify Globular Clusters (GCs) composed of objects like cataclysmic variables and compact binaries, which we can then use to determine the age and dynamic evolution of the universe. Observed clusters can be depicted in higher-resolution images, depending on the CCD used. CCD technologies present a variety of opportunities to model GCs. One of the main techniques for modeling GCs is generating a Color Magnitude Diagram, a method that uses stellar classification. CMDs find numerous potential applications in the areas of ultra-diffuse galaxies, GCs, and redshifts. However, there is still a lot of room for improvement in their utility. It is possible to enhance their properties by parameterizing the globular cluster denisty rating system. Moreover, modeling GCs with CMDs could facilitate improved chemical tagging in supernovae, which find many attractive applications in astronomy, such as building primordial models that could be replicated inside accelerators. |
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G00.00073: Effects of Gravitational Time Dilation during Balloon Satellite Flights with Chip Scale Atomic Clocks and their use in Small-Scale Systems Sean Huh, Timothy J Godsil, Robert Collier, Bryce Corkery The objective of this research project is to explore the theoretical principles of Gravitational Time Dilation as described by Einstein’s Theory of General Relativity, by collecting experimental data obtained via Chip Scale Atomic Clocks (CSACs) both aboard balloon satellite flights, as well as environmentally controlled ground stations; we demonstrate how Gravitational Time Dilation can be modeled and accurately accounted for using these differing scenarios as a basis for further calculations. We compare our experimental data against modeled estimates of Gravitational Time Dilation through a numerical integration process that incorporates multiple corrections to include environmental factors, position data, and other varying corrections. We expect that our model will significantly correspond to our experimental data, and that in-flight corrections will improve overall accuracy for determining the effects of Gravitational Time Dilation. We predict that Gravitational Time Dilation will be further verified and that our model will be accurate to within 5 nanoseconds. The model is expected to be useful in future development of an independent Local Positioning System / Accurate Time Keeping system using Chip Scale Atomic Clocks (CSACs); The ever-increasing reliability and need of position data and accurate time data is apparent in the worlds use of the Global Positioning System and the Coordinated-Universal Time standard; to combat the possibility of an intermittent or long-term loss of communication and infrastructure based on these standards, we investigate the concept of small-scale, ground-based, interconnected devices that provide sustainable and accurate time and positioning capabilities. |
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G00.00074: Seeking Hidden Helium in Type Ic Supernovae Desiree A Harvell, Abigail Polin The classification of core-collapse Type Ib and Ic supernovae (SNe) are defined by their spectra. Type Ib spectra contain Helium absorption features and Type Ic do not. It is an open question whether the lack of a helium detection in Type Ic SNe means there is no helium in the ejecta, or if there is helium in the outer layers that fails to impart a spectral signature. Stellar evolutionists have found difficulty in removing the helium layer in a stripped envelope star before a supernova (SN) event. Therefore, finding out why the potential helium goes undetected can benefit stellar evolutionists in their understanding of the stellar life cycle. We investigate the potential for “hidden helium” in stripped envelope SNe with the usage of simulated SN ejecta models. The radioactive 56Ni produced in the SN explosion is the main source of radiation that will stimulate the elements that appear on the spectra so changing the distribution may be highly influential. We vary the 56Ni distribution in a striped envelope explosion that contains helium in the outer layers of the ejecta. We hypothesize that a centralized 56Ni distribution will potentially result in weaker helium absorption features in the spectra. The findings of the experiment aim to answer if is possible for helium to still remain in the outer layers of Type Ic SN ejecta. |
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G00.00075: Discovery of Copper-Catalyzed Click Reaction Intermediates in Nanoreactor by Accelerated MD Shafat Mubin, Walker T Hayes, Todd J Martinez Click chemistry (Nobel Prize in Chemistry 2022) is characterized by small molecules acting as building blocks that can be joined to larger systems to build more complex molecules, with the copper-catalyzed azide-alkyne click reaction being the most prominent example. While catalysts are known to accelerate click reactions, the underlying reaction mechanisms and reaction intermediates have not been conclusively resolved. We approached this problem by constructing a first-principles based molecular dynamics simulation of the copper-catalyzed methylazide – propyne click reaction using the simulation platform Nanoreactor, which offers GPU-based capability in simulating dynamics and reaction events. Furthermore, the simulation was accelerated by an adaptive hyperdynamics algorithm to sample reactions over a larger time scale. By running the simulation at experimental conditions, we identified instances of reactions and subsequently identified species that could serve as reaction intermediates, including those not listed in literature. |
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G00.00076: Physics Fridays – undergraduate student led physics outreach program for K-12 kids. Patrick Herron, Jordan Miller In 2011 CSU’s chapter of SPS established an outreach program called Physics Fridays at Campus International School (CIS), a local K-8 Cleveland public school. Since then, physics students and CSU physics alumni have gone to CIS once a month through the academic year for an interactive physics exploration session with CIS students. The outreach program, which typically serves 30-50 kids in the CIS afterschool program, has won 11 Marsh W. White Awards from the National SPS. These awards have supported the significant part of the spring activities in the year-round program. Over the years, we have created a variety of fun and exciting inquiry-based lesson plans to engage kids with physics/science. Since its inception, we have had more than 55 Physics Friday sessions at CIS, each consisting of three or four different demo stations. Many of the outreach visits followed unique lesson plans, with no particular outreach session repeated more than 3 times. The lesson plans were created by an SPS outreach coordinator (we have been led by nine excellent coordinators since 2011) and their team of volunteers. Since 2011, more than 50 CSU students have participated in the Physics Fridays outreach lesson creation and execution along the way learning cool physics and quite a bit about themselves. This presentation will highlight our motivation and discuss the challenges and successes of our student-led outreach program. |
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G00.00077: Investigating Bromine Vacancy Coordination in CsPb(1-x)SnxBr2.875 Robert A Hoye, Daniel T Hickox-Young Halide perovskites are an important new class of materials for photovoltaic applications, providing high energy efficiency along with cheap solution-based synthesis methods. Initial research hypothesized that halide perovskites are ‘defect tolerant’, but more recent reports have revealed that low defect densities are the most likely cause for the surprisingly high energy efficiency of halide perovskites [Zhang et al., J. Appl. Phys. (2022) 131, 090901]. Therefore, optimizing the performance of halide perovskites requires minimizing recombination rates through control over defect energy levels. We investigate the interplay between Br vacancies and B cation mixing in CsPb(1-x)Sn(x)Br2.875. We use first principles density functional theory calculations to identify trends in the electronic structure and propose design rules for optimizing the ratio of B-site cations in halide perovskites. |
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G00.00078: Mechanical Irradiation Investigation of In Irradiation of Glassy Polymeric Carbon to Enhance Nuclear Safety Claudia M Imperiale ABSTRACT |
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G00.00079: Performance Comparison of Commercially-Available Rechargeable 2032 Batteries Simon Ji, Kai Yang Tan, Shintaro Inaba, Hillary L Smith Designed to be lightweight and long-lasting, 2032 coin cell batteries are a common type of battery used for applications ranging from wearable watches to motherboard components. Recent developments in battery technology has allowed rechargeable 2032 variants to enter the market, providing us with more sustainable alternatives to the commonly-used disposable CR2032 model. We report on a performance comparison between four available rechargeable 2032 battery models: LiR2032, LiR2032H, ML2032 and VL2032. The batteries are tested through galvanostatic cycling, under a range of temperature conditions between 0 and 60 ?. Destructive physical analysis was also carried out on each battery model to determine the composition of anode and cathode components using x-ray diffraction. An experimental sodium ion battery in 2032 coin cell configuration is also tested to benchmark its performance against the commercial lithium ion batteries. The viability of these commercial cells for a variety of applications will be discussed. |
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G00.00080: Simulations on the X(3872) Exotic Meson Eric Kirchner We investigated the X(3872) exotic meson candidate and explored the feasibility to research it using the future Electron-Ion Collider (EIC). $X(3872)$ is a tetraquark candidate: a meson that is composed of four quarks but requires additional investigation. We completed the study based upon based upon the generated values for 10,000 events. The parameters of the exotic meson explored include Mandelstam variables, mass, and pseudorapidity, among others. |
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G00.00081: Space Weather Forecasting by Sunspot Mapping and Solar Activity Correlation Daniel Klotz, Amar Rodgers, Liam Ohle A major portion of solar research and space weather forecasting is based on sunspot mapping. Sunspots, which are areas of the sun’s surface that appear darker due to a large buildup of plasma that is cooler than the rest of the surface, are created by the sun’s magnetic field and are highly correlated with the solar cycle. The quantity of sunspots indicates the amount of solar activity occurring. Solar flares and coronal mass ejections are caused by sudden changes in magnetic fields connecting sunspots. This research looks to find a correlation between the position of sunspots relative to one another and solar events. This will be done by mapping sunspots using a 16-inch (406-mm) Meade LX200 ACF f/8 telescope (ACF means Advanced Coma Free) and comparing the positions with solar activity reports. The primary goal of this research is to determine if sunspot positions can be used to forecast solar events that can disrupt and damage space-based systems. |
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G00.00082: A Simple Method to Determine Temperature Dependency of Thermal Diffusivity William X Li, Juncheng "Ryan" Bian, Yifei Jin, Lisa R Wang, William X Li We used the method we proposed previously (American Journal of Physics 90, 568 (2022); https://doi.org/10.1119/5.0087135) to further study thermal diffusivity's temperature dependency. Spheres of different radii, 15 mm, 20 mm, and 25mm, made of PMMA (Poly(methyl methacrylate)), are used to demonstrate the effectiveness of this method. We drilled a narrow channel to the center of the spherical shapes, inserted a thermocouple sensor into the center, and immersed the ball in boiling water. The center temperature was measured as a function of time. We tried to fit the time dependence of the center temperature to a heat-conduction model, with thermal diffusivity as a fitting parameter. We found that thermal diffusivity needs to be temperature dependent in order to obtain a good and consistent fitting result for all the samples. We developed a theoretical model which takes temperature dependency of thermal diffusivity into consideration. The derived thermal diffusivity and its temperature dependency for PMMA have good agreement with the data published in prior research. |
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G00.00083: Global-NILC: a bias reduction effort for NILC at large angular scale Yiqi Liu, Ivan L Padilla, Tobias A Marriage The detection of the polarization induced by the primordial gravitational wave (B-mode) in the Cosmic Microwave Background (CMB) is the primary focus for future CMB projects. However, the polarized Galactic foreground overwhelms the primordial polarization signature from the CMB at all frequencies, prompting the need for reliable component separation methods. The needlet internal linear combination method (NILC) is a blind component separation method constructed in the spherical wavelet (needlet) domain. NILC removes the Galactic foreground from the CMB signal using map-space variance minimization. The method is an internal linear combination (ILC) variant developed for the Wilkinson Microwave Anistropy Probe (WMAP) and later extensively used for analyzing data from the Planck mission. While NILC yields highly accurate results at small angular scale, the science of CMB concerns the large scale measurement of B-mode polarization. This project aim to improve the bias level for NILC at large angular scale. We applied our NILC variant to low-resolution maps. Our approach computes the theoretical CMB covariance matrices for each needlet window in the pixel space. We incorporate these covariance matrices into the ILC weight computation, taking information from both the theoretical CMB model and actual data into account. We assess our method with Monte Carlo simulations. Simulation results show clear progress reducing the bias level for NILC at large angular scales under different needlet decomposition schemes. |
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G00.00084: Characterizing Uncertainty of Violin Mobility Measurements Seth Lowery
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G00.00085: Probing NASA's Extragalactic Database for the Missing Mass Profile Alicia Mand, Balsa Terzic, Alexandre Deur, Corey J Sargent, William J Clark, Emerson Rogers, Antonia Seifert An area of extreme interest in astrophysics is the missing mass profile. This density profile, which depicts a discrepancy between the measured and predicted mass of spiral galaxies, shows that there is unobserved mass. This is traditionally described as "dark matter," and potential candidates for this missing mass include MOND, WIMPs, and primordial black holes. The aim of this research is to explore an alternative theory for this dark matter by describing the density profile of a galaxy using general relativity's self-interaction model for gravitational acceleration and accounting for any external field effects (EFE). In order to thoroughly investigate this model, we created simulated random galaxies reflecting observed correlations among galaxy parameters and created a corresponding density profile under the influence of self-interacting gravity. In addition, through the use of Python and the NASA Extragalactic Database (NED), we created web scraping tools to collect data on clusters of galaxies to improve our model. This poster presentation will discuss the creation and results of this tool and how it is being used to improve our current understanding of gravitational self-interaction and the missing mass profile. |
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G00.00086: Developing an Interactive Simulation for Non-Inertial Reference Frames Ted K Mburu The motion of non-inertial reference frames and the Coriolis and centrifugal forces involved in understanding these reference frames are challenging concepts for introductory and advanced mechanics students. Furthermore, students also find the prediction of the trajectory of an object due to these fictitious forces to be challenging. Even though non-inertial reference frames are things students encounter every day, they often only consider situations through a non-rotating frame of reference, where the Coriolis and centrifugal forces are often negligible. |
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G00.00087: Abstract for Determining Rotational Period of Asteroid 101955 Bennu through Analysis of IR Spectrometer (OVIRS) Data from OSIRIS-REx Emily McCallum, Sam Kreitzman The purpose of this research project is to utilize the MPO Canopus data processing software to analyze data from the IR Spectrometer (OVIRS) on OSIRIS-REx. The OSIRIS-REx Visible and Infrared Spectrometer (OVIRS) is a point spectrometer on OSIRIS-REx, the primary purpose of which is to map the surface composition of Bennu, a small asteroid that approaches Earth every six years and was formed in the early days of our solar system. Through MPO Canopus, we will use differential photometry to analyze the data collected by OVIRS during OSIRIS-REx's approach to Bennu. This will allow us to determine the rotational period of Bennu. This research will verify and expand upon our current capabilities with MPO Canopus, and it will be useful in providing an analysis of the data collected by OVIRS and determining whether it can be used to accurately determine Bennu's rotational period. |
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G00.00088: Applying Runs Tests to NOνA Data Brenna K McConnell The NuMI Off-Axis ν Appearance (NOνA) experiment has been in progress since 2014 to precisely measure neutrino characteristics including the mixing angle θ23 . Special interest revolves around whether θ23 is maximal, causing symmetry between the proportions of muon and tau neutrino flavors in the mass eigenstates. NOvA’s measurement of θ23 uses a χ2 calculation which estimates the likelihood for the data to have been drawn from parent distributions modeled with known values of θ23 . The χ2 test is independent of the signs of the differences between data and the parent distribution. This poster investigates the possibility of incorporating these differences by means of a Runs Test. The possible benefits of incorporating the Runs Test to NOvA’s θ23 measurement through simulations was tested. Inclusion of the Runs Test increased the experiment’s ability to discern θ23 = 40 from θ23 = 45 by Δχ2 = 1.13. This increase in Δχ2 is equivalent to increasing the data size by 12%, allowing statistically significant results to be achieved faster. Using Runs Tests could also be helpful in determining the mass ordering of neutrinos. |
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G00.00089: Computational Exploration of high energy density Metal Ion Electrode Materials Cielo M Medina Medina The current demand for power electronics and electric cars requires extensive exploration of Li-ion materials and similar technologies to meet the crucial factors of cost, safety, lifetime, durability, power density, and energy density in rechargeable batteries. In search for potential battery electrodes, Machine Learning techniques were used to predict average voltages and volume changes on metal ion electrodes, in our previous work. Through Machine Learning methods, various high energy density and small volume cell Li-ion electrodes were found. In this study, Li-ions were replaced with Na-ions to produce Na-ion electrodes in addition to the Li-ion materials. Voltage profiles and volume changes of several Li-ion and Na-ion electrodes were computed using DFT methods that showcase potential novel Li-ion and Na-ion materials for application as battery electrodes. |
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G00.00090: Optical Detection of Exoplanets using Transit Method with CTMO and McDonald Observatories Rudy A Morales We report Wasp-163b and Wasp-92b observations from CTMO. In addition, McDonald Observatory and CTMO Observatory observed KOI-4546 to assist confirm a Kepler Database exoplanet candidate. Observations and detection were made utilizing the Photometric Transit Method and a data reduction technique that eliminates picture flaws that might cause data processing inaccuracies. Astro-ImageJ is used to perform photometry on calibrated photos to determine the exoplanets' radius. Wasp-163b orbits its 1.12 stellar radius host star with a radius of 13.57 (Earth) and a mass of 594. (Earth). Wasp-92b orbits its F7 host star in 2.174 days and has a Jupiter-like mass of .806 and radius 1.467 (Jupiter). Both Wasp exoplanets are considered Super Jupiter's because to their masses and radii. KOI-4546 was a Kepler exoplanet candidate with a flux change at CTMO and McDonald Observatoires. |
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G00.00091: Convolutional Neural Network for Graphene Detection using Automated Optical Microscope Miguel A Moya, Sagar Bhandari Graphene has been used extensively as a platform for quantum physics research and for quantum-based electronic and optical applications. Graphene has unique electronic and optical properties which are attractive to researchers in various fields. However, graphene production is incredibly expensive, slow, and labor-intensive. It involves researchers searching for graphene flakes with the correct thickness under an opt microscope and finding the best geometry. In this talk, we present the design and implementation of a quicker cost-effective way of detecting graphene samples. Our approach to identifying samples is to apply a Convolutional neural networks algorithm to rapidly detect monolayer graphene. Currently, we have made great progress in automating the microscope and camera with stepper motors and creating a graphical interface to communicate with the system. Future progress entails training the convolutional neural network algorithm, with data from motors, and camera. This project aims to reduce the production costs and time of graphene by efficiently detecting usable samples. |
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G00.00092: Shock Interaction Effects on the Supernova Lightcurve Aidan J Nakhleh There is growing evidence that the emission from core-collapse supernovae is affected by the interaction between the supernova blastwave and its immediate surroundings (the circumstellar medium). Understanding the affect of these shock interactions on the supernova emission involves studying the complex coupling between radiation and hydrodynamics. Here we present a series of radiation-hydrodynamics calculations of shock interactions in supernova explosions, outlining the broad range of physical effects (e.g. shock heating, radiative acceleration) that alter the flow of the blastwave and the emission from these supernovae. These physics studies allow us to implement a methodology to include this physics into light-curve calculations and present the effect of shock interactions on observed supernovae. |
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G00.00093: Monitoring of the SND@LHC Detector Performance in Real Time Rebecca L Osar The Scattering and Neutrino Detector at the LHC (SND@LHC) is a new compact, stand-alone detector designed for precise measurements of neutrinos produced in collisions at the LHC in the pseudo-rapidity range of 7.2 |
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G00.00094: Finding Dynamical Chaos in Stellar ModelsComputational PhysicsUndergraduate Physics Research Giovanni Paz-Silva Stellar structure and evolution models are foundational to much of astrophysics by providing a big range in evolution calculations for astrophysics research. Since modern stellar evolution models can approach a precise stellar model followed by a series of equations that describe the chemical composition, fluid dynamics, thermodynamics, and other properties of stars that are calculated by astrophysics. These equations are highly complex, and it is in our goal to show if these equations and stellar model simulations are chaotic. |
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G00.00095: Using Social Network Analysis in Physics Education Research Geraldine L Cochran, Bermuda Pierre, Sheila Tabanli, Armando Merino, Schundnax Emmanuel
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G00.00096: Optimization problems in the development of a blimp to monitor radiation levels in the CERN FCC environment Vedant Rautela, Francesco Mazzei, Lorenzo Teofili To prevent unecessary human exposure to the extremely high levels of radiation present in the environment of the Future Circular Collider at CERN, robotic systems are a primary focus of research and development. Monitoring radiation levels, as well as other metrics, is a task well suited for flying robots which can access all unobstructed parts of a detector cavern. The blimp is the flying robot of choice for this task because of its relatively low likelihood of causing damage in the case of catastrophic failure of a motor. One challenge with developing a blimp for this purpose is the high magnetic field levels present in a detector cavern which interfere with the normal functioning of electromagnetic motors. Therefore, the design of a blimp requires not only a system to locate the blimp in space but also the capability to resist magnetic forces in any direction (and along any axis in the case of torques caused by magnetic forces). This work consisted of the determination of an optimal placement of cameras in a motion capture system used to locate the blimp in space as well as the determination of an optimal configuration of actuators on a blimp to allow it to counteract a desired set of disturbances. |
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G00.00097: Measurement of 1.3GHz Nb Cavity in High Magnetic Field for Axion Dark Matter Searches Mohammad Farhan Rawnak, Bianca Giaccone, Ivan Nekrashevich, Alexandr Netepenko, Sam Posen, Anna Grassellino The axion is one of the most compelling dark matter candidates that could solve both the dark matter mystery and the strong charge parity (CP) problem. Initial searches for the axion in high-energy and nuclear-physics experiments combined with astrophysical constraints suggested that the axion must be extremely light and exhibits very weak couplings to ordinary matter and radiation. Nevertheless, Sikivie proposed the axion haloscope technique in which the axion can convert into photons in the presence of a strong magnetic field via the inverse Primakoff effect. A large fraction of the axion parameter space is accessible using this technique. The two parameters that affect the effectivity of the axion search are the quality factor of the cavity and the external applied magnetic field. The typical axion haloscope uses normal conducting cavities with an internal quality factor, Q0 << Qaxion = 106 in the multi-Tesla field. Whereas the state-of-the-art superconducting radio frequency (SRF) niobium (Nb) cavities can achieve up to 1011. In order to understand if Nb SRF cavities can be successfully employed for axion haloscope searches, we investigated the quality factor degradation in presence of an applied magnetic field. In this poster, I will present the initial results of the study, focusing on the experimental setup, the measurement preparation, and the preliminary results of cavity Q0 degradation as a function of the applied magnetic field. |
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G00.00098: Computational Methods for Kepler's Law Michael G Rochette The purpose is to find solutions to Kepler's equation via python to find the position, velocity, or mass of the two celestial bodies given as a function of time. The first part employs the relaxation method to solve and plot Kepler's equation to find a value of eccentric anomaly (E) for a given value of mean anomaly (M) when the orbital eccentricity (e) is less than 1. The second portion involved an orbital eccentricity greater than 1. The third part of the program found the orbit of the Great Comet of 1680, employing the methods from the first case where the orbital eccentricity was less than one, where the orbital eccentricity and total period to orbit the sun are given. Results shown via graphs on the poster. |
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G00.00099: Application of Imaging Methods to Enhance Observatory Operation Amar Rodgers The West Point Observatory is looking to completely automate the Observatory to enable nighttime operation (beyond the curfew present at USMA). This is very experimental and consists of three broad tasks that are designed to be built on over time: complete the remote-in system needed to operate the dome without being present, gauge the effects of temperature on the focal length of the OTA, and streamline the workflow of taking pictures to make the operation of the dome easier for future cadets. This will be done using an attached temperature sensor, the SkyX Program, Deep Sky Stacker, and Adobe products like Lightroom and Photoshop. |
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G00.00100: Nonstandard Null Lagrangians and Gauge Functions and Dissipative Forces in Dynamics Ana Segovia Standard and non-standard Lagrangians that give the same |
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G00.00101: Energy Dependent Neutron Absorption Coefficients in Polyethylene Michael J Tan, Ari M Goldberg, Brooke Bolduc, Alexandra N Leeming, Molly R McDonough, Walter Johnson, Joseph McCormack, Nicholas Kirby, Jacqueline Nyamwanda, Jackson J Wiley, Michael J Tan In recent years, the Suffolk University Physics Department and the Massachusetts General Hospital (MGH) Radiation Oncology Department in Boston have collaborated in a series of experiments to determine the neutron energy distribution of an Americium-Beryllium (AmBe) source located at the MGH Proton Center. (The current and previous work has been supported by research grants from the Society of Physics Students.) The research reported builds on that work and makes use of the known energy distribution of the MGH AmBe source to determine the linear absorption coefficient for neutrons in different energy windows passing through polyethylene. Using an array of commercially available energy threshold bubble detectors and a series of polyethylene blocks of different thicknesses, we have determined neutron absorption coefficients in energy windows ranging from 0 to 20 MeV. An experimental design was used to mitigate backscattering that can cause artificially high bubble counts. The bubble detectors have energy dependent thresholds and known non-uniform cross sections in the different energy regions. The AmBe source activity previously determined in these six energy regions and the known bubble detector neutron cross sections was used to unfold the absorption coefficients of polyethylene. The results can be of use in neutron shielding studies. |
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G00.00102: Inertial Cavitation and its Relationship with Fluid Fill Height Connor A Tomlinson, Hans Peter Wagner, Heidrun Schmitzer, A.J. Norman, Peter Smith Cavitation occurs when a fluid is subjected to near-vacuum pressure caused by high acceleration of the container, which leads to homogeneous nucleation inside the fluid. This phenomenon can be observed with the formation of bubbles which collapse quickly. It is therefore of significant interest to study this phenomenon due to the bubbles ability to inflict damage on surfaces. An equation can be used to determine whether cavitation occurs. In this equation, the likelihood of cavitation to occur can be represented by the cavitation number "Ca." Cavitation occurs when the value of "Ca" is less than 1 and does not occur when the value of "Ca" is greater than 1. The relationship between the acceleration of the fluid and the fill height of the container determines whether cavitation occurs. Prior research indicates that, with increasing fill height, the cavitation number would decrease below critical, causing more cavitation. The goal of this research is to determine if the relationship between fill height is proportion or inversely related using a new, high-speed camera. In addition, the effects of the cavitation on the equipment and testing apparatus are also studied. |
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G00.00103: A New Way of Simulating Josephson Junction Circuits Xiangqin Wang Moore's law predicts the two-year doubling of transistor density on integrated circuits, but it has slowed down. In particular, the physical limits on the transistor size, heat dissipation by smaller transistors, and ascending demand for computing power send a clear note to the scientific community to develop more efficient computers. Superconducting digital, neuromorphic, or quantum computers have been promising solutions to the current challenges, and Josephson junction is at the heart of all of them. The state-of-art software for simulating Josephson junction circuits is WRSpice, which describes the circuits using differential-algebraic equations. The system can only be solved using a fixed-time step solver, leading to erroneous outputs due to insufficient resolution. We developed a new method of simulation based on graph theory that eliminates all algebraic equations and solves the system using a variable-time step solver, which allows more precise simulations of Josephson junction circuits. |
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G00.00104: Contributing to a Greener NY: Analysis of methane emissions in NYS Matthew D Weil, Eric M Leibensperger, Mikolaj Konieczny New York State is reducing its carbon footprint through the Community Leadership and Climate Protection Act. One important target is methane, a potent greenhouse gas that contributes 35% of the state's CO2-equivalent emissions. Here we present the results of mobile observations to better identify and quantify emissions of methane in central New York. Two mid-infrared absorption spectroscopy gas analyzers were mounted inside a van with an air inlet and weather sensor mounted on the roof. We used high resolution GPS data to map and analyze recorded observations. Applying Gauss's law as a form of mass balance, the amount of methane emitted from different sectors were estimated. Sites include farms, wastewater treatment plants, mines, landfills, and natural gas infrastructure. The largest and most consistent source from our sites comes from a large landfill, with more than 1000 kg CH4/hr of emissions. A more modest source of methane was discovered at numerous visits to a mining operation, including two distinct plumes with ethane:methane ratios of 0.010 and 0.007. The plumes are not from natural gas infrastructure, which has local ratios of 0.019. A DJI Matrice 600 Pro drone was used to collect airborne observations to assess the profile of the emission plume from a manure storage lagoon, which extended 6 m in depth. Our results show the utility of our methods to better account and track changes in methane emissions. |
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G00.00105: Simulating Antihydrogen Annihilation Distributions in ASACUSA's Cusp Trap Alison Weiss, Eric D Hunter The hyperfine structure of hydrogen is known very precisely, and if charge, parity and time reversal (CPT) symmetry holds, antihydrogen will have the exact same spectrum. CPT violation may help explain the baryon asymmetry, the mysterious and presently unexplained fact that the universe contains much more matter than antimatter. The Atomic Spectroscopy And Collisions Using Slow Antiprotons (ASACUSA) Collaboration aims to measure the ground state hyperfine structure of antihydrogen in a magnetic field-free region with a precision of 1 ppm. Antiproton and positron plasmas, which are produced further upstream, are combined in the Cusp trap. We use SIMION to simulate antihydrogen trajectories in the spatially varying magnetic field of ASACUSA's Cusp trap. We use the resulting annihilation distribution as a look-up table in a Python routine which accounts for plasma rotation and thermal velocity distribution. This work allows us to evaluate the antihydrogen ground state annihilation distributions for ranges of plasma properties, helping us to optimize antihydrogen production. |
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G00.00106: Determining the Rotational Period of an Asteroid Using Differential Lightcurve Photometry Jacob P Willis, Jaxon J Porter, Emily K McCallum, Paula Fekete The purpose of this project is to explore experimental methods of finding the rotational period of an asteroid. Using the West Point observatory, we collected experimental data on the light intensity of 4482 Frerebasil, an asteroid of unknown period with an absolute magnitude of 13.1. We differentially compared the light intensity of the asteroid with background stars to plot the relative brightness of Frerebasil over time. This research expands upon the capabilities of the West Point observatory, adding automation software and instrumentation to facilitate 8 hour imaging sessions. We expect this research to be useful in identifying which asteroids are well suited for robotic exploration and mineral harvesting. |
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G00.00107: Alternative procedure to calculate the basic reproduction number Ernesto P Esteban, Lusmeralis Almodovar-Abreu To control and manage the different waves of an endemic or epidemic disease, it is useful to know how quickly the contagious disease spreads. Two dimensionless numbers the basic (Ro) and effective (Re) reproduction numbers, provide such information. Furthermore, compartmental models are frequently employed in epidemiology to mimic infectious-disease dynamics. A review of the literature indicates that the next-generation matrix (NGM) method is the only approach used to obtain an analytical expression for the basic reproduction number (Ro). In this study, we aim to demonstrate a simpler, non-trivial procedure for calculating Ro in a closed form. The rationale for this undertaking is threefold. First, it provides an independent procedure to obtain the analytical value of Ro. Second, the proposed alternative procedure uses basic algebra, whereas the standard method (NGM) requires linear algebra. Third, the alternative method can be used to easily explain why Ro >1, implies an endemic disease. Finally, as an application we estimate the Ro and Re values for Puerto Rico during the 2020 pandemic. |
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G00.00108: Molecular Dynamic Simulation Incorporated with Science Pedagogy to Improve Undergraduate Students’ Authentic Engineering Problem-Solving Skills Sungwook Hong, Jiwon Hwang The current study aimed to use a guided inquiry-based instruction framework and other evidence-based science strategies to train undergraduate students with computational modeling and simulation skills to enhance their community-based authentic engineering problem-solving skills; particularly to study physical chemistry of complex nano-scale systems such as hydrocarbon and solid nanoparticles. We developed and implemented a one-month length of summer training program that consists of 16 sessions including software set-up, tutorials, hands-on activities, and a culminating project. The training program employed molecular dynamics (MD) simulations using the commercial ReaxFF-AMS software (https://www.scm.com/product/reaxff/) to model and design combustion processes of liquid- and solid- fuels, which can describe chemical reactions of complex systems at the atomic level. For the delivery of the program, guided inquiry-based instruction was used where students generate inquiry from their own experiences into authentic questions and are given opportunities to explore and discover science through inquiry; and explicit instructional components (i.e., a series of supports or scaffolds) were embedded within each stage of the inquiry cycle to augment the effect of inquiry-based instruction. During the program, dynamic representations and manipulation of abstract and unobservable phenomena (e.g., chemical reactions at molecular and atomic levels) were made available to students where they built molecular structures, ran MD simulations, and visualized and analyzed MD results. Students’ outcomes were measured both qualitatively and quantitatively. We measured students’ perception and motivation toward learning engineering via survey and written/verbal testimonial; and engineering problem-solving skills and MD application skills using the existing tools and researcher-developed evaluation criteria. Results indicated positive impacts of our pedagogical approached MD training. Implications and future directions will be discussed. |
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G00.00109: Bicircular Light-induced Space Symmetry Breaking in Topological Insulating States Hunter Ketels, Mahmoud M Asmar Periodic modulation of materials by optical drives has led to the discovery of non-equilibrium topological states of matter, such as the Floquet topological insulator. Conventionally, monochromatic and polarized light sources that break time-reversal symmetry while preserving inversion symmetry in matter have achieved materials’ topological phase tuning. A superposition of left and right circularly polarized sources of light with an integer frequency difference is known as bicircular (BC) light. In addition to breaking time-reversal symmetry, BC light facilitates the manipulation of materials’ space symmetries. In this work, we consider a three-dimensional topological insulator subjected to BC light, and we find the Floquet Hamiltonian of the system for a general light incidence direction. We determine the irradiated system’s effective Hamiltonian at high frequencies and characterize the light-induced terms’ space symmetries. Additionally, we analyze the dependence of light-induced effects on the BC light incidence direction, frequency ratio, and amplitude. Finally, our analysis characterizes the set of BC light parameters that facilitate the tuning of the topological insulator into a higher-order topological phase. |
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G00.00110: EARLY CAREER
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G00.00111: Adding learning degrees of freedom in biological tissues Sadjad Arzash, Indrajit Tah, Andrea J Liu, M Lisa L Manning Simple vertex models capture successfully many aspects of mechanical behavior of biological tissues, such as rigidity transitions. These cell-based models contain parameters such as preferred cell perimeters that govern the mechanics and dynamics of the system. Here, we allow these parameters to vary as new learning degrees of freedom to explore the mechanical rigidity of tissues. These additional degrees of freedom—on top of the physical degrees of freedom, namely the vertex positions—alter the energy landscape. We find that the rigidity transition can be shifted by introducing the preferred cell perimeters as transient degrees of freedom. Adding perimeter or area stiffnesses or preferred cell areas as new degrees of freedom, on the other hand, does not change the rigidity transition of tissues. |
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G00.00112: Generation and convergence of DNA and RNA structural ensembles Swapnil Baral, Satvik Manjigani, Joseph Robertson, Michael Zwolak DNA and RNA secondary and higher-order structure plays a central role in biology, medicine, bioengineering, and biomolecular nanotechnology, such as RNA therapeutics, Ribocomputing, and DNA origami. However, the study of nucleic acid secondary structure is demanding, as it spans an exponentially large phase space even when employing a high-level representation of structure. In other words, the low free energy manifold can be vast and have many structures contributing to observable or functional characteristics, such as hybridization efficiency, RNA programming errors, or assembly yield. We develop an approach to generate the equilibrium manifold and a conformational classification that enables testing ensemble convergence at varying degrees of fine graining. The procedure starts with a "seed" ensemble from an Ising-like spin model. This ensemble is transferred into a nucleic acid model (such as, oxDNA or oxRNA, but a fully atomistic description is also possible for smaller scale structures). Replica exchange anneals this seed ensemble. We then classify, via k-means and hierarchical clustering, structures according to a distance measure on the secondary structure. This permits testing both the convergence of the ensemble with respect to the number of members (i.e., the static ensemble) and the time dynamics (i.e., the dynamic ensemble). Nucleic acid ensembles are intractable despite the large growth in computational resources. Our approach efficiently generates an ensemble and endows it with a natural metric for convergence, an approach that can also be employed inhomogeneously to identify and converge regions of hypervariability. |
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G00.00113: Teichoic acids as organizing centers for growth and shape in Bacillus subtilis Felix Barber, Zhe Yuan, Enrique Rojas The Gram-positive cell wall is a rigid, sugar-peptide meshwork that constrains the cell's immense turgor pressure and confers cell shape. Specifically, rod shape is maintained through the circumferential orientation of the cell wall's peptidoglycan backbone by the Rod complex. Wall teichoic acids (WTAs) contribute up to 50% of the Gram-positive cell wall by mass and are known to assist with divalent cation homeostasis. However, a longstanding mystery is why preventing the first dedicated step of wall teichoic acid synthesis causes the complete loss of rod-shape. We used dynamical, quantitative microscopy to demonstrate that inhibiting wall teichoic acid synthesis causes a fundamental re-organization of peptidoglycan synthesis. Inhibiting WTA synthesis prompts a rapid decline in Rod complex activity coincident with a growth rate decrease. We further show that subsequent growth and the loss of rod-shape are then sustained by a separate pathway that inserts peptidoglycan isotropically. We posit that WTAs provide a fulcrum that quantitatively tunes the balance between oriented and isotropic cell wall synthesis, thereby maintaining cell shape and growth rate. |
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G00.00114: Defect mediated morphogenesis Livio Nicola Carenza, Ludwig A Hoffmann, Julia Eckert, Luca Giomi It has been a long-standing mystery how complex biological structures emerge during embryonic development from such seemingly uncoordinated building blocks as cells and tissues without guidance. Recent experiments suggested that misalignment in the collective structure –so called topological defects– could play a fundamental guiding role in morphogenesis. Here, we provide a theoretical study explaining how active defects interact with geometry and how this could play a crucial role in morphogenetic processes. Using a combination of computational fluid dynamics and analytics we study the instabilities of a cell monolayer in the framework of the active gel theory [1]. We consider an active polar liquid crystals coupled to an elastic deformable surface. We find that the cooperative interaction of active disclinations and geometry drives the buckling instability of the active membrane. This eventually results in the formation of long protrusions with a tentacle shape or even the nucleation of a vescicle. This work clarifies the interaction of active defects and geometry and provides potentially new insight into the physics beyond processes such as the metastatic cascade in cancer development or embryogenesis [2]. |
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G00.00115: ChemChaste: A hybrid continuum-discrete modelling software suite for simulating bacterial communities Connah G Johnson Bacterial communities, such as those contained within biofilms, are found in a wide range of industrial and clinical scenarios. They can be composed of multiple cell types which complicate the task of tackling film build up, such as in infections or marine biofouling. We seek to understand the biofilm wide dynamics through developing a hybrid continuum-discrete software library to complement experimentation and improve data informed biological modelling. By extending the widely used multi-scale simulation package Chaste, our open sourced software ChemChaste provides the means to simulate general reaction-diffusion PDEs coupled to individual cell models. Each cell within ChemChaste contains metabolic pathways, a personal cell cycle model, and membranous transport to enable the simulation of the complex chemical interactions within heterogeneous communities. Using ChemChaste we look to infer the role of environment-metabolic feedback on the community structure and consider how utilising multiple different cell types may protect a spatially distributed community from external stress or attack. Our results provide insights which may further our understanding of bacterial biofilms found in both industrial, and clinical, scenarios. |
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G00.00116: Physical model inspired by energetic jumping nematodes Sunny Kumar, Victor M Ortega-Jimenez, Ishant Tiwari, Saad Bhamla Nematodes are a taxon of microscopic worms that are more abundant than all individual animals combined. The majority of nematodes use undulatory propulsion to swim or crawl across wet conditions. Impressively, entomopathogenic nematodes which parasitize insects, are unique among roundworms because they can jump. Although the kinematics of this jumping behavior has been identified nearly 60 years ago, the energetics of elastic energy storage and release have remained unclear. Here, we utilize soft robophysical elastic structures including polymeric-based elastic cylinders and fluid-filled balloons (shells) to explore how the hydrostatic skeleton, cuticle, and muscles act as non-linear springs to store energy in the loop formation of the worm body prior to jumping. We specifically focus on the role of kinks (sharp folds) that are formed when these elastic cylindrical structures are bent beyond its buckling limit. We show that kinks in these highly deformable bodies could serve multifunctional roles: acting as a “capacitor”, enabling slow energy build-up and fast release; creating a non-linear spring for low-force, yet high energy loading; and finally offering stability during loop formation. Our study sheds insight into both how organisms exploit elastic instabilities for ultrafast motions while offering design motifs for soft jumping robots. |
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G00.00117: Modeling cell shape changes in the zebrafish embryo using a 3D vertex model Raj Kumar Manna, Emma M Retzlaff, Elizabeth Lawson-Keister, Michael Bates, Yiling Lan, Heidi Hehnly, Jeffrey D Amack, M Lisa L Manning Programmed cell shape changes in a developing embryo are essential for building many functional organs such as the neural tube, gut, and heart. Here we focus on Kupffer’s vesicle (KV) in the zebrafish embryo as a model organ, as it undergoes programmed asymmetric cell shape changes to establish the left-right axis of the embryo. A 3D Voronoi model, where the degrees of freedom are the cell centers, has previously demonstrated that the tailbud tissue surrounding the KV can generate drag forces and drive cell shape changes in KV. However, recent work has suggested that a 3D Vertex model, where the degrees of freedom are the vertices between cells, better captures realistic shape changes in systems with heterogenous architectures like the KV. Here we employ the 3D Vertex model to capture the propulsion of KV through tailbud tissue and study cell shape changes. We investigate KV cell shapes and cell distribution for a range of values of tailbud tissue fluidity and KV propulsion velocity, and compare to experiments. We further examine how the left-right asymmetric tailbud tissue mechanics, notochord-KV interaction, and differential propulsion of cells in KV influence the cell shape changes in KV. Our findings provide insight into the physical mechanisms that regulate organogenesis, and may help identify new targets for therapeutics. |
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G00.00118: Translocation of a cone-shaped HIV-1capsid through the nuclear pore complex Bhavya Mishra, Roya Zandi, Ajay Gopinathan In recent experiments, it has been observed that an intact cone-shaped HIV-1 capsid translocates through the nuclear pore complex (NPC) before the capsid disassembly within the host cell nucleus. Capsid translocation through NPC raises numerous concerns, such as how the capsid overcomes the nuclear protein (also called nup) created barrier within the pore. And since the HIV-1 capsid has a cone shape with a narrow tip and a broad back, will translocation be advantageous if the capsid enters the pore through a narrow end? We develop an analytical model for transporting viral cone-shaped HIV-1 capsid through the NPC, focusing on the energy barrier created by nups within the pore and the energy contribution of capsid-nup interaction to reduce the barrier. We analyze the system's free energy profile as capsid translocates along the pore. Derive the capsid's translocation probability for reaching the trans end of the pore. The results show how the capsid's translocation through NPC is more favorable if it enters through the narrow end rather than the wide end. Also, with the strength of the capsid-nup interaction, the capsid's probability of reaching the nucleus increases, and the translocation process fastens. At last, we propose an optimized shape of cargo for successful translocation through the nanopore. |
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G00.00119: Transcription-induced active forces suppress chromatin motion by inducing a transient disorder-to-order transition Sucheol Shin, Hyun Woo Cho, Guang Shi, Devarajan Thirumalai Recent experiments have shown that the mobility of human interphase chromosome decreases during transcription, and increases upon inhibiting transcription, a finding that is counter-intuitive because it is thought that the active mechanical force (F) generated by RNA polymerase II (RNAPII) on chromatin would render it more open and mobile. Inspired by these observations, we use a copolymer model to investigate how F affects the dynamical properties of a single chromatin. The movements of the loci in the gene-rich region are suppressed in an intermediate range of F, and are enhanced at small and large F values. In the intermediate F, the bond length between consecutive loci increases, becoming commensurate with the location of the minimum in the attractive interaction between the active loci. This results in a transient disorder-to-order transition, leading to the decreased mobility during transcription. Transient ordering of the loci in the gene-rich region might be a mechanism for nucleating a dynamic network involving transcription factors, RNAPII, and chromatin. |
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G00.00120: Tunable stiffness exhibited in entangled collectives of aquatic worms and biomimetic soft robots Ishant Tiwari, Harry Tuazon, Junghan Kwon, Robert J Wood, Justin Werfel, Saad Bhamla The California blackworm (Lumbriculus variegatus) is an aquatic worm that forms aggregate structures called worm blobs by twisting their slender bodies around other worms of its kind. These blobs provide a variety of advantages to the worm in its natural environment, ranging from protection from the elements, nourishment and better mobility than what is achievable in isolation. These entangled collectives have been found to tune their rigidity under varied stimuli. Here, we modulate the dissolved oxygen (DO) concentration inside the water to tune the worm blob's rigidity/entanglement. We measure the force applied by the blob under different DO concentrations, when subjected to external untangling forces. It is found that the blob applies a significantly larger force when in a high DO environment compared to when in a low DO one. We also find that their structural integrity is higher when present in high oxygen environments, showing typical solid like effects such as toppling over in the presence of unbalanced forces. The insights obtained from these biological aggregates have applications in development of soft robotic systems which can act as a "programmable glue" between substrates. |
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G00.00121: Gut Instincts: A data driven approach to mouse colon modeling Andrea J Welsh Colon motility, the spontaneous self-generated movement and motion of the colon muscle and its cells, is produced by activity in different types of cells such as myenteric neurons of the enteric nervous system (ENS), neurons of the autonomic nervous system (ANS) and interstitial cells of Cajal (ICC). Two colon motor patterns measured experimentally are motor complexes (MC) often associated with the propulsion of fecal contents, and ripple contractions which are involved in mixing and absorption. How ICC and neurons of the ENS and ANS interact to initiate and influence colon motility is still not completely understood. This makes it difficult to develop new therapies to restore function in pathological conditions. This talk will discuss statistical analysis of the optogenetic and calcium measurements of mouse colons and how it is implemented in the data-driven modeling of the ICCs and neurons that also capture the global dynamics that are observed in the colon. |
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G00.00122: Chromatin decompaction modulates the liquid phase behavior in nuclei of living cells Jing Xia, Cliff Brangwynne The cell nucleus can be thought of as a living substrate that functions to store and process cells’ genetic material. The genetic material is not randomly stored, but instead is packed into a network of chromatin fibers, whose organization is linked to various phase-separated nuclear bodies. While the structure of chromatin has been extensively studied, it remains unclear how its biophysical organization and mechanical properties impact phase separation inside the nucleus. Here, we utilize a biomimetic optogenetic system to interrogate the role of the chromatin network on the liquid-liquid phase separation in the nucleus of a living cell. We tune the density of the chromatin network with a histone deacetylases inhibitor (HDACi) and drive phase separation by shining blue light to oligomerize the proteins in the nucleus. We demonstrate that phase separation can be strongly inhibited once the dense heterochromatin network is decompacted by HDACi. We further show that the intranuclear mechanical properties change, with a corresponding change in phase behavior, including changes in the size of the phase-separated droplets, and altered coarsening dynamics. Our findings highlight the importance of the material state of the chromatin network for liquid-liquid phase separation in the nucleus, and have implications for the biophysical regulation of biomolecular condensates. |
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G00.00123: A Physics-Driven Self-Learning Transistor Network Sam J Dillavou, Benjamin Beyer, Menachem Stern, Jacob F Wycoff, Marc Z Miskin, Andrea J Liu, Douglas J Durian Artificial neural networks are powerful tools with an enormous breadth of uses, but their current implementation is reliant on a computational bottleneck - the processor. This restriction is costly both in speed and energy efficiency, and as a result there has been a push to develop distributed learning systems that do not require a processor or external memory. In previous work [1-3] we demonstrated the feasibility of a laboratory system that harnesses physics to perform the forward `computation’ and also exploits physics to enable local learning rules. When each edge of this system, an electrical network of variable resistors, follows these rules independently, the ensemble as a whole approximates gradient descent. Here we demonstrate the second generation implementation of such a system, which uses transistors as variable resistors. The laboratory network of 32 identical repeated edges is capable of performing non-trivial tasks, like data classification, and non-linear tasks, like XOR, without the aid of a processor. The new network is over 1000x faster than the first generation, and already outpaces its in silico counterpart. Furthermore, the new design lends itself easily to micro fabrication. This is important because the speed advantage is expected to grow with the size of the network. We observe the system's dynamics during learning and discuss its scalability, power consumption, and robustness. |
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G00.00124: Reducing Metal-Insulator interactions in Granular Metal High-Pass Filters Simeon J Gilbert, Michael P McGarry, Melissa L Meyerson, Samantha G Rosenberg, Paul G Kotula, Nathan J Madden, Peter A Sharma, Jack D Flicker, Michael P Siegal, Laura B Biedermann Several order of magnitude (OOM) on/off ratio improvements are shown for Mo-SiNx granular metals (GMs) compared to GMs with oxide insulators. Granular metals are nanostructured materials in which metal islands are separated by an insulator. At volume metal fractions (φ) below the percolation threshold (φc), GMs are insulating; electrical conduction occurs via electron tunneling and capacitive transport. These conduction mechanisms enable the creation of GM high-pass filters that are insulating below 1 kHz and conductive above 1 MHz. For high-pass filters, the DC conductivity, including tunneling, should be minimized while maintaining the capacitive transport. Au- and Ag-based GMs exhibit a desirable sharp conductivity (σ) knee at φc, with σ decreasing 4-6 OOM with Δφ≈0.1. However, Au and Ag GMs are not suitable for high temperature applications, and non-noble metals exhibit metal-insulator interactions that dramatically reduce Δσ at φc. The metal-insulator effects are minimized in high thermal stability Mo-SiNx by sputtering in a partial N2 environment, which reduces σ 3-4 OOM for φ<φc. Furthermore, post-growth annealing increases the separation distance between islands and results in >6 OOM decreases in σ at φc. These advancements in material quality improve high-pass filter performance. |
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G00.00125: Tunable clock transitions in lanthanide complexes for quantum information technologies Jakub Hruby, Krishnendu Kundu, Danh Ngo, Ryan Murphy, Randall McClain, Benjamin Harvey, Jeffrey R Long, Stephen Hill Bottom-up chemical synthesis of molecular spin qubit architectures represents a novel way for pursuing next-generation quantum technologies that could substantially influence all fields of human activity from complex structural biology to finance.1,2 Our work focuses on fine-tuning resonant clock transitions (CTs) within 4f n5d1 Ln(II) complexes, such that the associated transition frequencies, f, are insensitive to the local magnetic induction, B0, with df/dB0 → 0 at the CT minimum. This offers protection from magnetic noise and up to 10 times longer phase memory times, Tm, compared to conventional EPR transitions.3 As an added bonus, hyperfine CTs associated with significant s-d mixing in 4f n5d1 Ln(II) complexes minimizes spin-orbit coupling, leading also to enhanced spin-lattice relaxation times, T1.4 |
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G00.00126: Ghost sensing: the rise and role of exceptional points in planar geometry Emroz Khan, Evgenii Narimanov In optical biosensing, detection of small analytes at ultra-low concentration with a simple sensor device is an important challenging problem. A recent line of research promises enhanced sensitivity through operation based on exceptional points, which are spectral singularities present in open systems. When a sensor operates at an exceptional point it shows strong nonlinear response to external perturbation in contrast to usual linear behavior for traditional sensors. Although increased sensitivity has been demonstrated in several systems, they usually require non-trivial microscale geometry, high-Q resonators and precise control of optical loss and gain -- with a resulting complexity that so far prevented the use of these novel devices for practical biosensing. Here we show this complexity problem can be solved using the recent discovery of ghost waves, which are a special class of non-uniform electromagnetic waves in biaxial anisotropic media. Since these waves can be excited at the planar surface of bulk crystals, the need for complicated fabrication or doping is lifted. In addition to showing high sensitivity and precision, the proposed sensor is also shown to be robust against noise. The resulting ``ghost sensor" which derives its sensing enhancement through exceptional point-based operation and its device simplicity through manipulation of ghost waves in bulk optics, can enable applications ranging from clinical diagnosis and drug discovery to food process control and environmental monitoring to be more accurate and more affordable. |
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G00.00127: Integrated lithium niobate photonics and applications Amirhassan Shams-Ansari Over the last decade, the availability of high-quality thin-film lithium niobate (TFLN) and breakthroughs in nanofabrication techniques have enabled numerous integrated, efficient, and high-performance components with unique functionalities. Here, I will demonstrate several strategies for integrating lasers on TFLN platform which can lead to new opportunities in telecommunication, microwave photonics, and sensing. demonstrate high-performance and ultra-low loss devices in the thin-film lithium niobate platform for applications such as gas spectroscopy and data communication. First, we build a dual-comb interferometer based on cavity-based electro-optic frequency combs. With this, we perform a proof-of-concept spectrally-tailored multiplexed sensing benefits from the frequency stability of the comb sources. Next, I design an integrated electro-optic comb with ultra-dense comb spacing down to hundreds of MHz. I then introduce a modification to convectional TFLN fabrication (post-fabrication annealing, and carefully selecting the cladding material), which improves the minimum achievable loss on this platform by almost an order of magnitude. Our response measurement (self-calibrated via the Kerr nonlinearity) reveals that the intrinsic absorption-limited Q-factor on TFLN platform can be as high as 165 million opening door for transformative classical and quantum devices. In the end, I demonstrate a fully-integrated electrically-driven high-power laser transmitter on TFLN with more ~ 100 GHz bandwidth. This method allows for coupling more than 115 mW of optical power into thin-film lithium niobate waveguides. Finally, I discuss our novel technique for scalable laser integration and arbitrary THz waveform synthesis in TFLN platform. |
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G00.00128: Charge transfer dynamics in MoSe2/hBN/WSe2 heterostructures Yoseob Yoon, Zuocheng Zhang, Renee Sailus, Kenji Watanabe, Takashi Taniguchi, Sefaattin Tongay, feng wang Ultrafast charge transfer processes provide a facile way to create interlayer excitons in directly contacted transition metal dichalcogenide (TMD) layers. More sophisticated heterostructures composed of TMD/hBN/TMD enable new ways to control interlayer exciton properties and achieve novel exciton phenomena, such as exciton insulators and condensates, where longer lifetimes are desired. In this work, we experimentally study the charge transfer dynamics in a heterostructure composed of a 1-nm-thick hBN spacer between MoSe2 and WSe2 monolayers. We observe the hole transfer from MoSe2 to WSe2 through the hBN barrier with a time constant of 500 ps, which is over three orders of magnitude slower than that between TMD layers without a spacer. Furthermore, we observe strong competition between the charge transfer process and intralayer exciton-exciton annihilation processes at high excitation densities. Our work opens possibilities to understand charge transfer pathways in TMD/hBN/TMD heterostructures for the efficient generation and control of interlayer excitons. |
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G00.00129: Origin of the metal-insulator transition in the parent compounds of Ru-pnictide superconductors Niraj Aryal, Weiguo Yin, Emil S Bozin We study the interplay of the structural phase transition, flat electronic dispersion, and metal-to-insulator transition (MIT) in the parent compounds of the Ru-pnictide superconductors by using first-principles methods. Our electron and phonon calculations reveal that RuP and RuAs undergo MIT accompanied byorthorhombic to monoclinic distortion at low temperature, but RuSb stays orthorhombic and metallic, in agreement with the experimental findings. We find that although monoclinic distortion reduces the van Hove singularity at the Fermi level, a large monoclinic distortion is necessary for a clear MIT. Furthermore, we predict a light-induced two-step insulator-to-metal and structural transitions in the monoclinic phases of RuP and RuAs, which can be tested in future ultrafast pump-probe experiments. |
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G00.00130: Superconductivity in quantum Hall edge states Julien Barrier One can induce a supercurrent in a normal metal N by placing it between two superconducting electrodes S. It consists in transferring Cooper pairs through simultaneous conversion of electrons and holes at the NS interface. In a magnetic field, the electrons' and holes' trajectories bend and can no longer merge at the NS interface, rapidly destroying the proximity supercurrent. In ballistic systems however, electrons' and holes' trajectories can occasionally return to the same position after multiple bounces on mesoscopic edges [1]. In the QH regime, electrons and holes propagate in the same direction on the same edge, which does not support a supercurrent unless one manages to couple oppositely propagating edges. This can be achieved via chiral Andreev edge states in the superconducting sheath, resulting in critical current of ~1nA at 1.5T [2]. Narrow devices would show better coupling but increased backscattering. |
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G00.00131: Discovery of a topological quantum link Ilya Belopolski, Guoqing Chang, Tyler A Cochran, Zi-Jia Cheng, Xian Yang, Cole Hugelmeyer, Kaustuv Manna, Jia-Xin Yin, Guangming Cheng, Maksim Litskevich, Nana Shumiya, Songtian Sonia Zhang, Chandra Shekhar, Niels B Schröter, Alla Chikina, Craig Polley, Balasubramanian Thiagarajan, Mats Leandersson, Johan Adell, Shin-Ming Huang, Nan Yao, Vladimir N Strocov, Claudia Felser, Zahid M Hasan Quantum phases can be classified by topological invariants, which take on discrete values capturing global information about the quantum state. Over the past decades, these invariants have come to play a key role in describing matter, providing the foundation for understanding superfluids, magnets, the quantum Hall effect, topological insulators and Weyl semimetals. We introduce a remarkable linking number (knot theory) invariant associated with loops of electronic band crossings in the mirror-symmetric ferromagnet Co2MnGa [1-4]. Using state-of-the-art soft X-ray and vacuum ultraviolet ARPES, we observe three intertwined degeneracy loops in the bulk Brillouin zone three-torus, T3. We find that each loop links each other loop twice. Through systematic investigation of this linked loop quantum state, we explicitly draw its link diagram and conclude, in analogy with knot theory, that it exhibits linking number (2,2,2), providing a direct experimental determination of the topological invariant. On the sample surface, we further predict and observe Seifert boundary states protected by the bulk linked loops, suggestive of a Seifert bulk-boundary correspondence. Our observation of a quantum loop link motivates the application of knot theory to the exploration of quantum matter. |
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G00.00132: Twisted bilayers of thin film magnetic topological insulators Gaurav Chaudhary, Anton Burkov, Olle Heinonen Twisted bilayer graphene (TBG) near "magic angles" has emerged as a rich platform for strongly correlated states of two-dimensional Dirac semimetals. Here we show that twisted bilayers of thin-film magnetic topological insulators (MTI) with large in-plane magnetization can realize flat bands near 2D Dirac nodes. Using a simple model for thin films of MTIs, we derive a continuum model for two such MTIs, twisted by a small angle with respect to each other. When the magnetization is in-plane, we show that interlayer tunneling terms act as effective SU(2) vector potentials, which are known to lead to flat bands in TBG. We show that by changing the in-plane magnetization, it is possible to tune the twisted bilayer MTI band dispersion to quadratic band touching or to flat bands, similar to the TBG. If realized, this system can be a highly tunable platform for strongly correlated phases of two-dimensional Dirac semimetals. |
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G00.00133: The Hydra algorithm for simulating coupled U(1) systems Victor Drouin-Touchette Modified quantum Bose-Hubbard models and their classical counterparts, coupled XY models, have recently been shown to exhibit interesting phase diagrams, where the confinement/deconfinement of fractional vortices can lead to disordered phases with global U(1) symmetry that overall retain the discrete relative order. Whereas numerical studies in (1+1)D can be done efficiently via tensor network and DMRG studies, they become much more challenging in dimensions (2+1)D and higher. Here, we harness the efficiency of the worm algorithm at simulating XY models through nonlocal updates in their dual space. Adapting the worm algorithm to classical coupled XY models proves non-trivial and requires the interplay of many types of worms that can span the system whilst maintaining a modified Gauss' law constraint at each site. In this presentation, I show a modified worm algorithm where the head of the worms can fractionalize into many heads before eventually recombining. I will comment on the implication of such splinter and recombination events of the many-headed-worm, called a hydra, for the observation and measurement of confinement-deconfinement transitions in coupled XY models. Finally, I will provide a roadmap to where such coupled XY models and their quantum analogues, such as modified Bose-Hubbard models, can occur. |
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G00.00134: Triplet pairing from local moments – heavy fermion superconductivity from Hund's-Kondo interactions Tamaghna Hazra, Piers Coleman Almost all heavy-fermion candidate-triplet superconductors share the common structural motif of two or more U/Ce sublattices in the unit-cell separated by an inversion center. We present a pairing mechanism for triplet superconductivity that is enabled by such a locally non-centrosymmetric structure. Extremely high upper critical fields in these materials suggest the importance of local pairing scenarios with coherence lengths comparable to the lattice spacing. For instance, UTe2 remains superconducting at fields above 60T, suggesting a coherence length shorter than 2nm. A legitimate driver of these local triplet pairing correlations is atomic Hund's coupling, which leads to pre-formed triplet pairs between the electrons trapped inside local moments. The sublattice degree of freedom allows these onsite spin-triplet pairs to acquire odd-parity form factors as they Kondo-hybridize with the dispersive electrons, leading to a pairing instability in a triplet channel. We show how the Hund's coupling modifies the Kondo hybridization leading to an anisotropic ``triplet'' Kondo coupling. Using a simple two-channel Kondo model, derived from a minimal mixed-valent construction with Hund's coupling, we demonstrate the emergence of odd-parity spin-triplet superconductivity in a mean-field calculation. This unifies the emergence of triplet superconductivity with the Kondo hybridization in a coherent framework, and we present support for this hypothesis from existing experiments. |
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G00.00135: Topology in magnetic phases of SmB6 Moritz M Hirschmann, Huimei Liu, George A Sawatzky, Giniyat Khaliullin, Andreas P Schnyder SmB6 is a mixed valence compound and a well known candidate material for topological Kondo insulators. With the application of pressure the valence of Sm atoms increases and as a consequence antiferromagnetism emerges in experiments. |
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G00.00136: Quantum spin Hall state at Room temperature Md. Shafayat Hossain, Nana Shumiya, Jiaxin Yin, Maksim Litskevich, Zhiwei Wang, Chiho Yoon, Fan Zhang, Qi Zhang, Brian W Casas, Luis Balicas, Zijia Cheng, Tay-Rong Chang, Titus Neupert, Yugui Yao, Shuang Jia, Guangming Cheng, Nan Yao, Zahid M Hasan Search for macroscopic quantum phenomena at room temperature is a major pursuit in physics. There has been only a single definitive report of such a phenomenon, namely the room-temperature integer quantum Hall effect at ultra-high magnetic fields [1]. In this poster, I will present our discovery of a zero-magnetic field, room-temperature quantum phenomena- quantum spin Hall state featuring a bulk energy gap and a gapless, in-gap edge state protected by the time-reversal symmetry [2]. Our material platform is Bi4Br4, which has a large energy gap, facilitating the high-temperature robustness of the quantum spin Hall state. |
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G00.00137: Visualizing the interplay of Dirac mass gap and magnetism at nanoscale in intrinsic magnetic topological insulators Mengke Liu, Chao Lei, Hyunsue Kim, Yanxing Li, Lisa Frammolino, Jiaqiang Yan, Allan H Macdonald, Chih-Kang Shih In intrinsic magnetic topological insulators, Dirac surface state gaps are prerequisites for quantum anomalous Hall and axion insulating states. Unambiguous experimental identification of these gaps has proved to be a challenge, however. Here we use molecular beam epitaxy to grow intrinsic MnBi2Te4 thin films. Using scanning tunneling microscopy/spectroscopy, we directly visualize the Dirac mass gap and its disappearance below and above the magnetic order temperature. We further reveal the interplay of Dirac mass gaps and local magnetic defects. We find that in high defect regions, the Dirac mass gap collapses. Ab initio and coupled Dirac cone model calculations provide insight into the microscopic origin of the correlation between defect density and spatial gap variations. This work provides unambiguous identification of the Dirac mass gap in MnBi2Te4, and by revealing the microscopic origin of its gap variation, establishes a material design principle for realizing exotic states in intrinsic magnetic topological insulators. |
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G00.00138: A three-stage magnetic phase transition revealed in ultrahigh-quality van der Waals bulk magnet CrSBr Wenhao Liu, Xiaoyu Guo, Jonathan Schwartz, Robert Hovden, Liuyan Zhao, Bing Lv van der Waals (vdW) magnets are receiving ever-growing attention nowadays due to their significance in both fundamental researches on low-dimensional magnetism and potential applications in spintronic devices. The high crystalline quality of vdW magnets is the key to maintaining intrinsic magnetic and electronic properties, especially when exfoliated down to the two-dimensional (2D) limit. Here, ultrahigh-quality air-stable vdW CrSBr crystals are synthesized using the direct solid-vapor synthesis method. The high single crystallinity and spatial homogeneity have been thoroughly evidenced at length scale from sub-mm to atomic resolution by X-ray diffraction, second harmonic generation, and scanning transmission electron microscopy. More importantly, specific heat measurements of ultrahigh-quality CrSBr crystals show three thermodynamic anomalies at 185K, 156K, and 132K, revealing a stage-by-stage development of the magnetic order upon cooling, which is also corroborated with the magnetization and transport results. Our ultrahigh-quality CrSBr can further be exfoliated down to monolayers and bilayers easily, providing the building blocks of heterostructures for spintronic and magneto-optoelectronic applications. |
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G00.00139: Topological magneto-electric response in non-magnetic and anti-ferromagnetic topological insulators Perry T Mahon, Chao Lei, Allan H MacDonald The theory of magneto-electric response in topological insulators is confusing because bulk calculations yield a topologically protected non-zero result that is forbidden by time-reversal symmetry. The theoretical bulk response is expressed as an integral over three-dimensional momentum space that is quantized. This conundrum can be resolved by recognizing the importance of time-reversal symmetry breaking at the surface. Evidently in this instance the bulk theory does not fully explain the magneto-electric phenomenology of real devices, and this has created some confusion in the literature. For instance, in thin-films for which time-reversal symmetry is not broken either in the bulk or at the surface, topological insulators have no magneto-electric response. Here we consider the magneto-electric response of non-magnetic and anti-ferromagnetic multilayer crystals. We develop tight-binding Hamiltonians for both cases, which are special in the sense that the bulk magneto-electric response coefficient can be evaluated analytically in a Hamiltonian gauge. Motivated by the modern theory of magnetization, and by numerical thin-film calculations for the same model which are presented in a related talk by Lei, Mahon, and MacDonald, we compare the structures of the bulk momentum-space integrands between the two cases and discuss bulk/surface decompositions of the total response. |
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G00.00140: Direct probing of strong magnon-photon coupling in a planar geometry Anish Rai We demonstrate direct probing of strong magnon-photon coupling using Brillouin light scattering spectroscopy in a planar geometry. Miniaturized, planar device design is imperative for the potential integration of magnonic hybrid systems in future coherent information technologies. The magnonic hybrid system comprises a split-ring resonator loaded with epitaxial yttrium iron garnet thin films of 200 nm and 2.46 µm thickness. The Brillouin light scattering (BLS) measurements are combined with microwave spectroscopy measurements where both biasing magnetic field and microwave excitation frequency are varied. The cooperativity for the 200 nm-thick YIG films is found to be 1.1, and larger cooperativity of 29.1 is found for the 2.46 µm-thick YIG film. We reveal that BLS is advantageous for probing the magnonic character of magnon-photon polaritons, while microwave absorption is more sensitive to the photonic nature. Furthermore, successfully detecting the magnonic hybrid excitation by BLS is an essential step for the up conversion of quantum signals from the optical to the microwave regime in hybrid quantum systems. |
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G00.00141: Anomalously high supercurrent density in a two-dimensional topological material Qi Zhang Ongoing advances in superconductors continue to revolutionize technology thanks to the increasingly versatile and robust availability of lossless supercurrent. In particular, high supercurrent density can lead to more efficient and compact power transmission lines, high-field magnets, as well as high-performance nanoscale radiation detectors and superconducting spintronics. Here, we report the discovery of an unprecedentedly high superconducting critical current density (17 MA/cm2 at 0 T and 7 MA/cm2 at 8 T) in a two-dimensional superconductor. The compound features a strongly anisotropic (both in- and out-of-plane) superconducting state that violates the Pauli paramagnetic limit signaling the presence of unconventional superconductivity. Spectroscopic imaging of the vortices further substantiates the anisotropic nature of the superconducting state. More intriguingly, the normal state carries topological properties. The band structure obtained via angle-resolved photoemission spectroscopy and first-principles calculations points to a Z2 topological invariant. The concomitance of topology and superconductivity establishes it as a topological superconductor candidate, which is promising for the development of quantum computing technology. |
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G00.00142: The Effects of Motile Bacteria on Viscous Fingering Jane Y Chui, Harold Auradou, Jeffrey S Guasto, Ruben Juanes Viscous fingering is a hydrodynamic instability that occurs when a less viscous fluid displaces a more viscous one. Instead of progressing as a uniform front, the displacing fluid forms fingers that vary in size and shape to form complex patterns. The interface created from these patterns affects mixing between the two fluids, and therefore understanding how these patterns evolve in time is essential in applications such as enhanced oil recovery, bioremediation, and microfluidics. |
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G00.00143: Effect of imposed shear on falling liquid films with variable fluid properties Souradip Chattopadhyay, Akshay S Desai, Hangjie Ji We present a study on the dynamics of a gravity-driven thin liquid film flow on a uniformly heated inclined plane in the presence of imposed shear stress. Based on the lubrication theory, we develop an evolution equation for the film thickness that accounts for gravity, shear stress, and temperature-dependent fluid properties. Linear stability analysis for this equation yields critical conditions for the onset of instability in long-wave perturbations. The analysis also shows the dependence of the critical Reynolds number on the direction of the imposed shear stress as well as other flow parameters. In addition, we perform a weakly nonlinear stability analysis based on the method of multiple scales and obtain a complex Ginzburg Landau equation. We observe that the film not only has supercritical stable and subcritical unstable zones, but also unconditional stable and explosive zones. Numerical simulations of the model are conducted to further investigate the spatiotemporal behavior of nonlinear waves by applying a constant shear stress in the upstream and downstream directions. Finally, we study the energy transfer from the base state to the disturbances in the presence of the imposed shear stress. |
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G00.00144: Jamming distance: a physics-informed design parameter for dense suspension rheology Shravan Pradeep, Lilian C Hsiao, Paulo E Arratia, Douglas J Jerolmack Dense suspensions are ubiquitous in everyday life: with applications ranging from household products to geophysical flows. These suspensions are complex in nature, with constituent particles exhibiting polydispersity, roughness, and interactions. By decoupling the effects of two complexities: surface roughness and interparticle interactions, we a propose a single parameter - jamming distance - that can unify the flow behavior in dense suspensions. Jamming distance can be defined as the spatial distance of a given suspension from its jamming point. From a physical viewpoint, jamming point is the concentration where the flow properties, namely the suspension viscosity, diverges. The effect of the surface roughness on dense suspension flow mechanics was studied using model smooth and rough PMMA colloids by performing rheological experiments at low strains (linear regime) and high shear rates (non-linear regime). At low strains, close to the suspension jamming point, the viscoelastic moduli of rough suspensions were thousand fold higher compared to the smooth suspensions due to the enhanced hydrodynamic lubrication interactions between the rough surface asperities in close contact. At high shear rates, dense suspensions shear thickened and we observed a universal correlation between the rate of shear thickening and jamming distance in colloidal suspensions. Using confocal rheometry, we characterized one of the first experimental 3D contact networks and found that jamming distance represented a scaled volume to rearrange particles during shear. Next, we studied real-life dense mixtures which are heterogenous in nature and have complex interactions. We found that steady shear flow curves of natural debris suspensions can be explained using a simple Bingham-fluid model, if the jamming distance-dependent viscous stresses are taken into account. Thus, our work eluciates that a single parameter, jamming distance, as a powerful tool to design and study flow mechanics in dense suspensions, from model suspension mixtures to natural geophysical flows. |
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G00.00145: Investigating how physics programs take up to a collaborative and data-informed approach to change Diana Sachmpazidi, Chandra Turpen, Robert P Dalka As calls for increased accountability influence institutional practices, a cultural facet that has received increased attention is the culture of assessment. In this project, we study the change process enacted by local Departmental Action Teams (DATs) resulting from physics faculty members' participation in the Departmental Leadership Action Institutes (DALIs). We developed case studies of three DALI-active physics programs. We investigate cultural shifts by following these programs for over a year, collecting data from multiple sources. We document the departments' dominant culture around the use of data and how the emerging microculture within the DAT is situated within that dominant culture. We find that past data collection efforts were a primary responsibility of a single person, rarely becoming the focus of joint attention. Whenever data received joint attention, it was approached in a cursory way without meaningfully informing collective change efforts. However, we found that within the DATs, data played a significant role in understanding the root causes of the problem. Finally, we found that a broad set of DAT stakeholders engaged in extensive collective discussions around the design of data collection and interpretation of findings |
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G00.00146: Triboelectric charging of particles: From the early onset of planet formation to assembling crystals Kai Sotthewes, Han Gardeniers, Gert Desmet, Ignaas Jimidar Triboelectrification is the spontaneous charging of two bodies when released from contact. Even though its manifestation is commonplace in triboelectric nanogenerators, scientists find the tribocharging mechanism a mystery. The primary aim is to provide an overview of different tribocharging concepts that have been applied to study and realize the formation of ordered stable structures using different objects on various length scales. Relevance spans from materials to planet formations. Especially dry assembly methods of particles of different shapes based on tribocharging to obtain crystal structures or monolayers are considered. In addition, the current technology employed to examine tribocharging in (semi-)dry environments is discussed as well as the relevant forces playing a role in the assembly process. In brief, this review is expected to provide a better understanding of tribocharging in assembling objects on the nano- and micrometre scale. |
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G00.00147: Morpho: A programmable environment for shape optimization and shape-shifting Chaitanya S Joshi, Daniel Goldstein, Cole E Wennerholm, Eoghan Downey, Emmett Hamilton, Samuel Hocking, Anca Andrei, James Adler, Timothy J Atherton Materials that change shape, often dramatically, are ubiquitous in soft matter physics and beyond. Determining their structure requires minimizing a given energy functional with respect to the shape of the domain and auxiliary fields describing the structure. Such shape optimization problems are very challenging to solve and there is a lack of suitable simulation tools that are both readily accessible and general purpose. We address this gap with Morpho, an open-source programmable environment for shape optimization and shape-shifting. Capable of simultaneously optimizing for shape and fields in any number of dimensions, Morpho can be used to model a host of soft matter systems and beyond. We showcase examples from diverse systems ranging from biological membranes, liquid crystal tactoids, constrained flexible filaments and swelling hydrogels. |
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G00.00148: How machine learning and an information theory perspective can enrich research on complex systems Kieran A Murphy, Dani S Bassett One of the first steps toward understanding a complex system with a multitude of interacting elements is to identify the most informative measurements that can be made. What are the detectable precursors to rearrangement in a disordered solid, or the most informative tests to perform on a hospital patient for predicting eventual outcome? While the search is often navigated heuristically based on an intuitive notion of information, in this work we ground the process in information theory and then employ machine learning and data to the same end. Specifically, we use machine learning to optimize a variant of the Information Bottleneck that allocates information across multiple measurements. In doing so, we map out the information in a complex system as a powerful means to deeper understanding. |
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G00.00149: Particulated Granular Metamaterials Dong Wang, Jerry Zhang, Weiwei Jin, Annie Xia, Nidhi Pashine, Rebecca Kramer-Bottiglio, Mark D Shattuck, Corey S O'Hern Granular materials display complex mechanical response. For example, the ensemble-averaged shear modulus <G> increases with pressure as P0.5 in the large-system limit when particles are allowed to rearrange during isotropic compression. In this work, we seek granular materials with shear moduli that decrease with increasing pressure even in the large-system limit. To do this, we design “particulated” granular metamaterials composed of multiple cubic “voxels” each containing jammed packings of a small number of spheres (N < 8). As shown in previous studies, G typically decreases linearly with P for a single voxel containing a small number of spheres with a slope that depends on the angle of the shear. We show that the behavior of G versus P for granular metamaterials made up of a large number of voxels (each with N < 8) is controlled by the ratio of the particle-particle and particle-wall interactions. In particular, we are able to achieve large particulated granular metamaterials for which G decreases with increasing P. |
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G00.00150: Better Than Worst-Case Decoding for Quantum Error Correction Gokul Subramanian Ravi, Jonathan M Baker, Arash Fayyazi, Sophia F Lin, Ali Javadi-Abhari, Massoud Pedram, Frederic T Chong The overheads of classical decoding for quantum error correction grow rapidly with the number of logical qubits and their code distance. Decoding at room temperature is bottle-necked by refrigerator I/O bandwidth while cryogenic on-chip decoding is limited by area/power/thermal budget. |
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G00.00151: Piezoelectric effect at cryogenic temperatures: finding robust materials platforms for electromechanical quantum transduction Deepak Sapkota, Kathryn Evancho, Christopher M Rouleau, Margaret Marte, Jong K Keum, Kasra Sardashti Quantum transduction, which refers to the conversion of a quantum signal from one form of energy to another form has been actively studied in the field of quantum information science and technology. Here, we survey a range of materials with various lattice constants, electronic band-gaps, and piezoelectric responses for cryogenic quantum transduction applications. We determine that thin-film titanates are promising materials for such applications. We present a systematic investigation of the physical and chemical characteristics of epitaxial barium titanate (BTO) thin film, a possible candidate for quantum transduction. Using pulsed laser deposition, we epitaxially grow barium titanate (BTO) on silicon and GaAs substrates using very thin buffer layers of YSZ, CeO2, STO and LaNiO3. The BTO heterostructures are characterized by X-ray diffraction, atomic force microscopy, and transmission electron microscopy. Furthermore, to evaluate potential phase change of the material at very low temperatures, we utilized cryogenic X-ray diffraction and electrical measurements including dielectric constant. |
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G00.00152: Emergent Z2 phase transition in the magnetization plateau. Madhumita Sarkar, Krishnendu Sengupta, Arnab Sen, Mainak Pal We study the phase diagram of Rydberg ladders having n = 2, 3 legs in the presence of both staggered and uniform detuning with amplitudes Δ and λ respectively. We show that these ladders host a plateau with fixed Rydberg excitation density 1/(2 n) for a wide range of λ/Δ. Our analysis further unravels the existence of an emergent quantum phase transition stabilized via an order-by-disorder mechanism inside the plateau. This transition belongs to the Ising (three-state Potts) universality class for ladders with n = 2(3) legs. We identify the competing terms responsible for this transition and estimate the critical detuning as λc/Δ = (n − 1) / (n + 1), which agrees well with exact-diagonalization based numerical studies. We also study the fate of this transition for a realistic interaction potential, which allows for the possibility of direct verification of this transition in standard experiments. |
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G00.00153: Unified theory of the anomalous and topological Hall effects with phase-space Berry curvatures Nishchhal Verma, Zachariah M Addison, Mohit Randeria Spontaneously broken time-reversal symmetry in magnetic materials leads to a Hall response, with a nonzero voltage transverse to an applied current, even in the absence of external magnetic fields. It is common to analyze the Hall resistivity of chiral magnets as the sum of two terms: an anomalous Hall effect arising from spin-orbit coupling and a topological Hall signal coming from skyrmions, which are topologically nontrivial spin textures. The theoretical justification for such a decomposition has long remained an open problem. Using a controlled semiclassical approach that includes all phase-space Berry curvatures, we show that the solution of the Boltzmann equation leads to a Hall resistivity that is just the sum of an anomalous term arising from momentum-space cur- vature and a topological term related to the real-space curvature. We also present numerically exact results from a Kubo formalism that complement the semiclassical approach. |
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G00.00154: Stripe Helical Magnetism and Two Regimes of Anomalous Hall Effect in NdAlGe Hung-Yu Yang, Jonathan Gaudet, Rahul Verma, Santu Baidya, Faranak Bahrami, Xiaohan Yao, Cheng-Yi Huang, Lisa M DeBeer-Schmitt, Adam A Aczel, Guangyong Xu, Hsin Lin, Arun Bansil, Bahadur Singh, Fazel Tafti Recently, the discovery of helical magnetism induced by Weyl-mediated exchange interactions in NdAlSi, a Weyl semimetal breaking both inversion and time-reversal symmetries, provides a new example of topological magnetism contributed by Weyl nodes. However, it remains a question that whether or not the topological magnetism persists in its sibling compound NdAlGe. In addition, with the presence of topological magnetism, it is not clear how Weyl nodes may affect the transport properties of these materials. Here, we provide conclusive evidence that NdAlGe also hosts the same type of topological magnetism as NdAlSi. The transport properties, however, differ greatly between NdAlSi and NdAlGe in carrier concentrations, mobility, and anomalous Hall effect (AHE). In particular, we did not find a clear sign of AHE in NdAlSi, but we observe two regimes of AHE in NdAlGe, governed by intrinsic Berry curvature and extrinsic disorders/spin fluctuations, respectively. Our study suggests that compared to topological magnetism, transport properties including AHE in Weyl semimetals are generally involved with more material specifics and more susceptible to disorders. |
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G00.00155: Interplay between next nearest neighbor hopping and long-range antiferromagnetism in t-J models with doping Luhang Yang, Ignacio Hamad, Luis O Manuel, Adrian E Feiguin We present a numerical study of the competing orders in the 1D t-J model with long-range RKKY-like unfrustrated spin interactions. By circumventing the constraints imposed by Mermin-Wagner's theorem, this Hamiltonian accommodates long-range N'eel order at half-filling. We determine the full phase diagram as a function of the exchange and particle density using the density matrix renormalization group (DMRG) method. We show that in this model, pairing is disfavored and the AFM insulator and metallic phases are separated by a broad regime with phase segregation, before spin-charge separation re-emerges at low densities. Upon doping, interactions induce a confining potential that binds holons and spinons into full fledged fermionic quasi-particles in a range of parameters and densities. In addition, we include next nearest neighbor(NNN) hopping terms t' into the model. By tuning the sign and magnitude of t', the superconducting phase is partially restored for some doping densities. We discuss how this simple toy-model can teach us about the phenomenology of its higher dimensional counterpart. |
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G00.00156: Fluctuation population mediated order to disorder stripe phase transition in amorphous Fe-Ge thin film ARNAB SINGH, Emily M Hollingworth, Sophie A Morley, Ahmad Us Saleheen, Ryan Tumbleson, Margaret R McCarter, Peter J Fischer, Frances Hellman, Stephen D Kevan, Sujoy Roy Chiral spin-structures like stripes, helices, skyrmions, merons and hopfions has been of great research interest due to their technological implication in magnetic and spintronic devices. Usually, the topological skyrmion phase evolves from a ground state of helical phase in single crystals or stripe phase in thin films. Understanding how the system evolves near phase transition is a key to get insights into the formation of these exotic spin-phases through proper tuning of the external parameters. In this work we study the spin-dynamics near the stripe phase transition of amorphous Fe-Ge thin films using soft x-ray photon correlation spectroscopy (XPCS). Amorphous FexGe1-x thin films shows an order to disorder stripe phase transition at around 250K and paramagnetic ordering above room temperature for x=0.53. Using the coherence of the x-ray photons we constructed 2D maps of the nanoscale magnetic speckle fluctuations near the phase transition. Such fluctuation maps in Q-space give details about the dynamics of domains of different morphologies present in the real space. We observe that the fluctuation population grows as we increase the temperature, and it peaks near the stripe phase transition before falling off. Interestingly the fluctuation density continues to increase as the paramagnetic transition is approached. This new study provides a more specific way of locating critical phase-transition points through growth of fluctuation population and can be used over a wide variety of systems. |
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G00.00157: Appearance of Odd-Frequency Superconductivity in a Relativistic Scenario Patrick J Wong, Alexander V Balatsky Odd-frequency superconductivity is an exotic pairing mode in superconducting systems in which the symmetry of the gap function is odd in energy. Here we show that an inherent odd-frequency mode emerges dynamically under application of a Lorentz transformation of the anomalous Green function with an anisotropic gap function. To see this, we consider a Dirac model with quartic potential and perform a mean-field analysis to obtain a relativistic Bogoliubov-de Gennes system. Solving the resulting Gor'kov equations yields expressions for relativistic normal and anomalous Green functions. The form of the relativistically invariant pairing term is chosen such that it reduces to BCS form in the non-relativistic limit. We choose an ansatz for the gap function in a particular frame which is even-frequency and analyze the effects on the anomalous Green function under a boost into a relativistic frame. In the boosted frame the order parameter contains terms which are both even and odd in frequency: Δ(ω,k) ~ ω2 → γ2ω2 + β2γ2k2 + 2βγ2kω. The relativistic correction to the anomalous Green function to first order in the boost parameter is completely odd in frequency. The odd-frequency pairing emerges dynamically as a result of the boost. This work provides evidence that odd-frequency pairing may form intrinsically within superconductors. |
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G00.00158: Optical Signatures of Many-body Interactions in Few-layer Semiconductor Zhengguang Lu, Yuxuan Jiang, Dmitry L Shcherbakov, Li Xiang, Zhigang Jiang, Chun Ning Lau, Dmitry Smirnov The family of III-VI metal monochalcogenides, for example, Indium selenide (InSe), emerge as new two-dimensional materials with a layer dependent band structure, high electron mobility and strong light matter interaction. Monolayer InSe is predicted to be an indirect band gap semiconductor. However, few-layer InSe maintains direct band gap optical properties and hosts a flat valence band dispersion. Here we report the observation of the electrical field controlled neutral and charged excitons in high-quality hBN encapsulated few-layer InSe devices. Near the charge neutrality point, the photoluminescence (PL) spectra display a strong and narrow peak with 4meV linewidth (at 20K) associated with the recombination of neutral excitons. By increasing the carrier density, positive (negative) charged trions are observed and manifest a red (blue) energy shift. The observation is a direct signature of the many-body interaction induced by the flat valence band. |
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G00.00159: Elastoresistivity measurement of kagome metal CsV3Sb5 Zhaoyu Liu, Yue Shi, Qianni Jiang, Elliott W Rosenberg, Jonathan M DeStefano, Zhiwei Wang, Jiun-Haw Chu The recently discovered kagome metal CsV3Sb5 has attracted enormous attention due to its nontrivial topological electronic structure and intertwined symmetry-broken states [1,2]. One central question is the nature of the broken symmetry associated with the charge density wave (CDW) onsets at T ~ 90K [3,4]. In this talk, I will present the measurement of elastoresistivity and elastocaloric effect of CsV3Sb5. Using three different techniques, the differential, the modified Montgomery, and the transverse method, we precisely decomposed the elastoresistivity coefficient into different symmetry channels. We found that the isotropic elastoresistivity coefficient (i.e., m11+m12) increases substantially below the charge density wave transition temperature and becomes several times larger than the nearly temperature-independent anisotropic coefficient (i.e., m11-m12). Our results suggest that the charge density wave phase in CsV3Sb5 either does not break rotational symmetry or its broken rotational symmetry is decoupled from the anisotropic strain. |
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G00.00160: Phonon-polaritons in the deep-strong coupling regime Andrey Baydin, Manukumara Manjappa, Sobhan Subhra Mishra, Hongjing Xu, Fuyang Tay, Dasom Kim, Felix G Hernandez, Paulo Rappl, Eduardo Abramof, Ranjan Singh, Junichiro Kono Formation of polaritons in the ultrastrong and deep-strong (DSC) coupling regimes provides opportunities for exploring novel phases of light–matter hybrids as well as for applications in quantum information processing and technology. Phonon-polaritons are particularly interesting as they are expected to be able to modify and control chemical reactions and superconductivity; they are also predicted to induce a new type of ferroelectric phase transitions. Here, we investigate coupling between vacuum photons and phonons in lead telluride in small-mode-volume terahertz cavities. Using metamaterial cavities to enhance vacuum fluctuation fields in the terahertz range, we observed a Rabi splitting whose value exceeded the cavity-phonon frequency, placing us in the DSC regime. We systematically studied the coupling strength as a function of sample thickness, temperature, and cavity length. These experimental results will be discussed in comparison with results of electromagnetic simulations we conducted. |
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G00.00161: Microstructure-Dependent Optical Properties of Doped Spinel Oxide Nanosystems David Beke Doped spinel crystals show long-lasting emissions (LLP) in the visible and near-IR regions that can be activated by X-ray or UV-visible light. Such properties make this material a promising candidate for background-free deep-tissue bioimaging, photodynamic or photon-induced therapy (PIT), optical sensing, and many other applications. The optical properties, however, are highly dependent on the dopant environment and the nature of the trap states responsible for the LLP. Annealing changes the defect structures of Cr and the trap states and the strength of the energy transfer between the different Cr defects and significantly affects the optical properties. We found crystal field decrease at low temperatures caused by quasi-melted pseudocrystalline surface, making them temperature sensitive, an order of magnitude increase in the photon yield upon X-ray or UV illumination, and temperature-dependent LLP. The outcome of the fundamental research on the defect structure is that at optimum annealing conditions, activating the IR700 photoactive dye used in PIT, with X-ray excitation, or by the LLP that promises PIT for deep-seated or embedded tumors or other diseases is possible. |
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G00.00162: Discovering the extreme limits to semiconductor band gaps Sieun Chae The magnitude of the band gap has been traditionally applied as a criterion to distinguish semiconductors from insulators; materials with gaps less than 3 eV are typically semiconductors, while wider-gap materials tend to be insulators. However, the development of ultra-wide-band-gap (UWBG) semiconductors such as AlGaN, diamond, BN, and β-Ga2O3 has challenged this gap-based criterion for materials classification and gave rise to questions such as how far the band gap of semiconductors can increase while maintaining delocalized carriers for conductivity and what is the widest band gap semiconductor. By applying high-throughput density functional theory calculation, we develop a materials discovery strategy to identify new extreme-gap semiconductors. We discover that materials composed of light elements, crystallized in simple, densely packed structures, and having s-orbital characteristics of conduction/valence bands have large band gap (> 7 eV) but light carrier effective mass (me* < 0.7 me mh* < 2 me) that enable shallow dopants and high mobility and suppress the formation of polarons. Among the UWBG compounds, we identify rutile GeO2 is an UWBG (4.68 eV) semiconductor with material properties surpassing the state-of-the-art materials and demonstrate the first film growth of single crystalline r-GeO2. Our work motivates further exploration of r-GeO2 as well as other UWBG semiconductors with even wider gaps as alternative UWBG semiconductors that can advance the power electronics and optoelectronics technologies. |
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G00.00163: Optical detection of antiferromagnetic dynamics in CrCl3 Shekhar Das, Alex L Melendez, I-Hsuan Kao, Francisco Ayala Rodriguez, Simranjeet Singh, P Chris Hammel Nitrogen-vacancy (NV) centers in diamond and newly discovered Boron-vacancy (BV) centers in h-BN also known as color-centers provide a non-invasive and sensitive method to probe weak magnetic field fluctuations generated by magnons. Enabling the detection of magnetic dynamics at frequencies exceeding the color-center ESR frequency (typically a few GHz) is essential in order to probe the dynamics of many ferri- and antiferromagnetic materials. The recent discovery of optical detection of magnetic resonance occurring above the NV center ESR frequency reveals a route to the exploration of the antiferromagnetic spin dynamics [1,2]. The scattering of two high-frequency magnons, or two-magnon scattering, generates electromagnetic noise at their difference frequency which can match the color-center frequency enabling the detection of higher-frequency dynamics. Here, we show the optical detection of antiferromagnetic resonance in a bulk CrCl3 crystal. At 9 K, the optical branch resonates at 9 GHz, three times larger than the NV center ESR frequency. The temperature evolution of the resonance mode confirms that it originates from antiferromagnetic dynamics. Such dynamics can also be excited using spin-orbit torque (SOT) generated by current in an adjacent layer. The low in-plane symmetry of WTe2 generates an out-of-plane SOT component excites antiferromagnetic dynamics measured using NV/BV centers in diamond/hBN. |
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G00.00164: Tuning Metal Halide Perovskite Electronic Structures by the Incorporation of Iron Dopants David Deibert Metal halide perovskites have seen widespread use as photovoltaics. One such reason metal halide perovskites are attractive is due to their directly tunable band structure.1 One such method to tailor perovskites for their desired application is the introduction of a dopant to the structure of the perovskite.2,3 Using first-principal techniques, we simulate the introduction of iron dopant configurations into a HfSnS3 perovskite and analyze the effects on the electronic structure. |
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G00.00165: A mixed enthalpy-entropy descriptor for the design and high-throughput screening of high-entropy materials Dibyendu Dey, Liangbo Liang, Liping Yu Over recent years, considerable research has been carried out to understand the design principles for the stability and synthesis of high-entropy materials (HEMs). In most cases, either enthalpy- or entropy-based formalism has been adopted to build a descriptor to understand the composition-structure-property relationships of these complex systems. However, both thermodynamic quantities play crucial roles in governing the stability of HEMs. In this work, we propose a Mixed Enthalpy-Entropy Descriptor (MEED), which features an actuating enthalpy-entropy competition that underlies the stability and formation of solid solutions. By using robust and efficient first-principles high-throughput screening of the carbides and 2D disulfides of metals (Hf, Nb, Mo, Ta, Ti, V, W, and Zr), the MEED successfully identifies all experimentally reported single-phase HEMs in these two groups comprising four, five, and six principal metal elements. The known HEMs are not only clearly separated from those element combinations that form multiple phases, but also the relative magnitudes of their growth temperatures have been estimated. With MEED, additional new high-entropy carbides and 2D high-entropy transition metal disulfides have been predicted. |
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G00.00166: A real-space self-similarity based method for describing, constructing and understanding quasicrystals and phason flips Domagoj Fijan, Andrew T Cadotte, Sharon C Glotzer Quasicrystals (QC) are structures with perfect order but lacking translational symmetry. Consequently, they possess some very peculiar properties, such as self-similarity, and exhibit unique internal structural rearrangements called phason flips. The state-of-the-art in understanding quasicrystals today involves the use of higher- dimensional methods, of which the most important is the project-and-cut method. This method requires facility in mapping to 5-D or higher-dimensional space, which for many researchers poses a considerable obstacle to developing an intuitive understanding of the structural complexity of quasicrystals. Although simpler, real-space approaches to understand quasicrystal structure exist (such as inflation/deflation and covering), these approaches are intrinsically unable to describe phason flips. Here we propose a new quasi-unit cell framework for describing, categorizing, constructing and understanding quasicrystals based on their self-similarity. Our framework utilizes a newly developed concept we call layering, which can explain and predict phason flips based solely on the structure of the quasi-unit cell. We show how the new framework applies to several popular 2-dimensional QC models (Penrose tilings, Ammann-Beenker tiling, etc.). |
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G00.00167: Dynamic atomic off-centering and its selective coupling with phonons in KTa(1-x)NbxO3 Xing He, Olivier Delaire, Douglas L Abernathy, Garrett E Granroth, Feng Ye, Lynn A Boatner The mechanism of ferroelectric phase transitions (e.g. displacive or order-disorder) in simple compounds like BaTiO3 and KNbO3 has remained debated for decades. Finally solving this question requires simultaneously resolving atomic dynamics, local crystal distortions and complex correlated disorder. To address this challenge, we map the energy and momentum resolved dynamic structure factor S(Q, E) with neutron scattering and we perform DFT-accuracy machine-learning MD (MLMD) simulations, to rationalize the spatial and temporal correlations of atomic disorder and the coupling with phonons. Here, we focus on correlated atomic off-centering in KTaO3 and KTa(1−x)NbxO3 (KTN) and find an intermediate picture between displacive and order-disorder scenarios. Our experiments show two-dimensional diffuse sheets from correlated local disorder in KTN, contrasting with displacive KTaO3. Our first-principles and MLMD simulations reveal that correlated 1D chains of off-centered B-site atoms in KTN are energetically favorable, and show how the correlated disorder selectively couples with the ferroelectric instability as well as transverse acoustic modes. These results provide insights into these model systems and offer general guidance for related systems whose atomistic behavior remain debated. |
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G00.00168: Extension of orbital lifetimes of silicon-vacancy centers in diamond using phononic crystals KAZUHIRO KURUMA, Benjamin Pingault, Cleaven Chia, Michael Haas, Graham Joe, Daniel R Assumpcao, Marko Loncar Silicon-vacancy (SiV) centers in diamond are promising solid-state quantum emitters for various quantum photonic applications because of their strong and stable zero phonon line emission and optically accessible spin. However, their spin coherence time is short at 4K, mainly limited by phonon transitions between ground-state orbital branches. In this work, we demonstrate suppression of the phonon transitions by using phononic crystals (PnCs) to control the phonon density of states. We fabricate free-standing 1D PnCs with a complete phononic bandgap using a quasi-isotropic etching technique on single-crystal diamond. We observe a more than ten-fold increase in orbital lifetimes for single SiVs embedded in PnCs compared to SiVs in bulk, with values of up to 500 ns. This result demonstrates the potential of PnCs to control emitter-phonon interactions and paves the way for developing quantum network nodes using SiV centers in PnCs. |
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G00.00169: Solid-phase epitaxial crystallization of complex oxides in nanoscale complex geometries Rui Liu, Deepankar Sri Gyan, Peng Zuo, Samuel D Marks, Donald E Savage, Tao Zhou, Zhonghou Cai, Martin Holt, Serkan Butun, Shaoning Lu, Nasir Basit, Xiaobing Hu, Tirzah Abbott, Nathaniel Kabat, Susan E Babcock, Thomas F Kuech, Paul G Evans Lateral crystallization of the model perovskite oxide SrTiO3 from an amorphous precursor can be seeded by selected areas of the surface of a patterned SrTiO3 (001) single-crystal substrate. The crystallized SrTiO3 exhibits a rotating lattice microstructure in which the crystallographic orientation evolves continuously as a function of the lateral crystallization distance. Complementary synchrotron x-ray nanobeam diffraction imaging and high-resolution TEM studies measured the rotation rate resulting from crystallization at 550 °C was 50° per μm of lateral crystallization. Key features, including the rotation rate and the direction of the rotation, were reproduced in each of the many lithographically patterned seeds. The results of structural characterization studies are consistent with a model in which the rotation results from a high concentration of dislocations, on the order of 1 per 10 nm of crystallization distance, with a non-random population of Burgers vectors. The nucleation of dislocations with the preferred Burgers vector occurs due to stress near the amorphous-crystalline interface arising from the large volume difference (16%) between amorphous and crystalline SrTiO3. The development of the rotating lattice microstructure has the potential to enable the creation of complex oxides in stress and orientation configurations not available through other epitaxial growth methods. |
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G00.00170: Polarization dependent magneto-Raman study of phonons and magnons in CoTiO3 Thuc T Mai, Maria F Munoz, Tehseen Adel, Yufei Li, Kevin F Garrity, Daniel Shaw, Timothy N DeLazzer, Jeffrey R Simpson, Kate A Ross, Rolando Valdes Aguilar, Angela R Hight Walker We performed a study of the symmetry of the Raman active phonons and magnons in exotic quantum magnet CoTiO3. Using polarization dependent Raman, we mapped out the symmetry of the various quasiparticles in an isotropic and anisotropic cut of the sample, the ab-plane and ac-plane respectively. The study was carried out in its magnetically ordered phase below 38 K. In addition, we measured the polarization dependent of the magnons as a function of applied magnetic field. The results are analyzed using the Raman tensors of the magnetic point group in the ordered phase. |
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G00.00171: Magneto-Optical Properties of Methylammonium Lead Iodide Perovskite Thin Films in the Orthorhombic domain Maria F Munoz, Angela R Hight Walker, He Wang, Xinwen Zhang Hybrid lead halide perovskites have opened a new era for photovoltaics research over the last decade due to their high energy conversion energy. These materials are promising for future electronics and optoelectronics and applications in spin-electronic devices due to their unique properties, such as high coherent emission, spin-orbit coupling, and strong light-matter interaction [1]. Recent experimental and theoretical studies have shown that the polar organic cations affect the lattice polarization, giving rise to a ferroelectric behavior and enhancing their photovoltaic performance [2]. Furthermore, magnetism in halide perovskite at room temperature has been confirmed, suggesting a route toward spintronics applications based on magneto-optical perovskites [3-4]. However, the hybrid perovskites' magnetic properties are not well understood. Our work reports magneto-photoluminescence (MPL) and magneto-Raman (MR) measurements of methylammonium lead iodide CH3NH3PbI3 (MAPbI3) ~ 280 nm thin film materials at low temperatures (<60 K), where the crystalline structure is in the orthorhombic domain. We obtained different MPL spectra from random spots on the sample surface and fitted them with gaussian curves at 55 K and 1.6 K. The MPL spectra confirm the existence of a dual emission peak at a low temperature, consistent with previous works [5]. For each spot, we applied a magnetic field up to 9T in the perpendicular direction of the surface and analyzed the MPL plots as a function of the external magnetic field. Changes in the intensity, the central position, and the FWHM of the gaussian components were observed in the MPL spectra. We also compare the response of the thin film at room temperature (tetragonal domain) under the external magnetic field to the low temperature data. |
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G00.00172: A Route Towards Actinide Heterostructure Synthesis and Science Kevin D Vallejo, Brelon J May, Cody Dennett, Paul J Simmonds, David H Hurley, Krzysztof Gofryk The presence of 5f electrons in actinide materials enables them, and their compounds, to possess unique physics not found anywhere else in the periodic table. While they have a wide set of applications as nuclear fuel materials due to their inherent radioactivity, the aspects of their fundamental physics remains comparatively unexplored. In order to uncover some of the phenomena that arise from their unique electronic configuration, it is paramount that samples are the highest quality possible: monocrystalline, low defect density, and low density of impurities. In addition, governmental regulations and safety standards make this material system difficult to work with. Idaho National Laboratory has a long standing history of working with nuclear materials and has created a path for the synthesis and characterization of high quality actinide samples using molecular beam epitaxy (MBE). A new MBE chamber has been recently commissioned to address this need, to study critical materials for the nuclear industry, their surrogates, and the fundamental physics underlying their synthesis and properties. In addition to uranium and thorium (5f electron containing and non-containing elements, respectively) we have added cerium, zirconium, manganese, nickel, and chromium to our chamber in order to establish a robust program of research around actinides and related compounds. Results from these studies have the potential to provide validation for computational models with strongly-correlated electrons and to uncover novel alloys for nuclear applications and beyond. |
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G00.00173: Ab initio simulation of optical absorption in noble metals and plasmonic ceramics Xiao Zhang, Emmanouil Kioupakis Modeling the complex dielectric function of metallic system is the key to understand their applications as plasmonic materials. While traditional plasmonic materials such as noble metals (Au, Ag) have been well-studied by experiments, theoretical characterizations of these materials, as well as emerging new plasmonic ceramics that can endure extreme conditions, have been limited to merely the semi-classical Drude model. However, in the infrared region, phonon-assisted absorption is an important contribution to the total absorption in metallic systems due to the presence of large amount of free carriers. In this poster, we will present our work on the characterization of optical response of metals and plasmonic ceramics by considering phonon-assisted indirect transitions, direct transitions, and resistive absorption. Our calculated optical spectra of Ag, Au, and TiN show excellent agreement with experiment. Our work provides a tool to systematically characterize optical response of metals from first principles, enabling rational design of new plasmonic materials. |
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G00.00174: Characterizing penetration of a contaminant into block copolymer coatings Krishnaroop Chaudhuri, Riddhiman Medhi, Zhenglin Zhang, ZHUOYUN CAI, Anthony Malanoski, Brandy White, Christopher K Ober, Jonathan Pham Polymer coatings are critical as protective barriers and it would be beneficial to understand how the polymer properties relate to small molecule penetration into coatings. Towards this goal, we investigate how a model dye molecule penetrates into block copolymer coatings. In a typical experiment, a drop of fluorescent Rhodamine B dye solution of known concentration is placed on a coating of micron-order thickness, while confocal microscopy is used to visualize the resultant fluorescence inside the coating over time. As a starting point, block copolymers are synthesized with polystyrene (PS) blocks and modifiable polydimethylsiloxane (PDMS) blocks. Using image analysis methods, we track the temporal and spatial fluorescence distribution in the coating. A model based on first principles is developed to determine the rate of penetration; we find that the rate of dye penetration into the coating is a function of the initial dye concentration and the PDMS content in the block copolymers. Ultimately, we expect that a better understanding of how small molecules penetrate into polymers will help guide the design of more effective coatings for a wide range of applications. |
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G00.00175: Pairwise Similarity of Polymer Ensembles Jiale Shi, Dylan Walsh, Debra J Audus, Bradley D Olsen In contrast to small molecules having well-defined molecular structures, polymers are rarely a single, well-defined structure. Instead, they are ensembles composed of polymer chains with various sequences, topologies, and molar mass distributions. While there are numerous approaches to measuring the pairwise similarity of small molecules, accurately calculating the pairwise similarity between polymer ensembles is still challenging. A common approach is to generate a single embedding vector for each ensemble and subsequently compute the distance between these vectors to yield a similarity score. For example, the embedding of a random copolymer can be defined by a weighted average of embedding vectors of the repeat units. However, these common average approaches neglect significant features. Here, we explicitly consider all the entities of the ensembles in the calculation of the similarity score and show that our method captures differences that are neglected using the average method, enabling us to resolve subtle differences between molecular distributions. Our method presents a critical step to quantitatively calculate polymer ensemble similarity and enable nearest neighbor search in polymer database. |
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G00.00176: Light-activated micro-swimmers in a thermotropic liquid crystal Antonio Tavera-Vazquez, Danai montalvan, Gustavo Perez, Sam Rubin, Noe d Atzin, Walter Alvarado, Vinothan N Manoharan, Juan J De Pablo Over the last decade, studies of artificial micro-swimmers have significantly mimicked the dynamics of those in nature. However, most research has been focused on isotropic liquids hosts, with fewer studies dedicated to structured media. In this work, we designed two self-propelled systems at different length scales in a nematic fluid. The first one consists of solid platelets with sizes of hundreds of microns, formed after drying droplets of a light-absorbing dye. The second one comprehends Janus silica particles half-coated with titanium. Both systems are immersed in a thermotropic liquid crystal (LC), and their mobility is triggered by light. The light-absorbing materials are heated, consequently inducing a localized LC nematic-isotropic (NI) phase transition. The inhomogeneous distribution of light-absorbing spots contributes to the unevenly formed NI interface. As a result, the platelets and Janus particles move. We show the differences between both systems’ dynamics and optical responses. A discussion of the characteristics that induce mobility in each case is also presented. This research helps to unveil the micro-swimmers’ dynamics at different length scales and different geometry, immersed in a highly structured media. |
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G00.00177: Elastic flow instability enhances solute mixing in 3D porous media Christopher A Browne, Sujit S Datta Polymer solutions are often injected in porous media for applications such as groundwater remediation, column chromatography, or packed bed reactions. In these settings, it is often important to mix solutes in initially separated streams. For Newtonian fluids, the flow is typically laminar, limiting mixing to the dispersion inherent to the disordered pore space. However, it remains unknown how polymer solutions modify this mixing. Here, we directly visualize the mixing of two fluorescently dyed streams within a transparent 3D porous medium. We find that, above a threshold flow rate, the mixing rate increases above the expected laminar dispersion. By imaging the pore-scale velocity field, we demonstrate that the increase in solute mixing rate is concomitant with the onset of an elastic instability in which the flow exhibits strong spatio-temporal fluctuations reminiscent of inertial turbulence, despite the vanishingly small Reynolds number. This elastic instability produces a spectrum of solute concentration fluctuations that follow power-law scalings consistent with Batchelor mixing. Thus, by linking macro-scale mixing to the pore-scale unstable flow, our work provides generally-applicable guidelines to control mixing of passive scalars in disordered porous media. |
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G00.00178: Effect of polymer architecture on gelation and reversibility in photocrosslinkable polymer hydrogels Michael C Burroughs, Tracy H Schloemer, Daniel N Congreve, Danielle J Mai Polymer hydrogels exhibit mechanical properties that depend on material composition, molecular architecture, and processing route. The gelation and uncrosslinking kinetics of reversible, network-forming polymer solutions were investigated using in situ dynamic rheology measurements. Reversible, network-forming polymers comprised either 3-, 4-, or 8-arm star polyethylene glycol (PEG) with terminal anthracene groups, which dimerize under irradiation with 365 nm ultraviolet (UV) light and undimerize with deep UV light (265 nm). Upon 365 nm UV exposure, PEG-anthracene solutions exhibited rapid gel formation as indicated by the crossover from liquid-like to solid-like behavior during in situ small-amplitude oscillatory shear rheology. The time required to form a sample-spanning gel was non-monotonic with polymer concentration. Reversion of the polymer hydrogels to uncrosslinked polymer solutions was monitored by time-dependent changes to the viscoelastic moduli upon exposure to 265 nm deep UV light. Overall, these findings quantify the effects of polymer molecular weight, number of arms, and material composition on the (un)crosslinking kinetics and mechanical properties of multi-arm star polymer hydrogels. |
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G00.00179: "Liquid network" theory of supramolecular soft matter networks Michael S Dimitriyev, Gregory M Grason Macromolecules can self-assemble into a variety of ordered nanostructures, including the triply-periodic double-gyroid and double-diamond network phases. These phases consist of complex, intercatenated, labyrinthine domains, yet are supramolecular soft crystals with long-range order. Interruptions to their crystal symmetries, e.g. due to defects or composition gradients, result in collective changes in domain morphology as a result of thermodynamic forces and constraints on molecular packing. Motivated by experiments and self-consistent field calculations of block copolymer melts, we propose a "liquid network" theory that coarse-grains the collective behavior of such supramolecular networks into an effective mechanical network model. Unlike canonical models of mechanical networks, our theory describes networks whose struts possess a length-independent line tension, and is thus characterized by the mathematics of so-called Steiner networks. We show that our model reproduces key observations of experiments and simulations, namely significant non-affinity of node displacements and highly correlated bond angles. Finally, we discuss structural transformations under shear and deformation pathways that facilitate transitions between different network phases. |
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G00.00180: Exploring mechanisms of enhanced dissipation in nanoparticle-filled rubber using molecular dynamics Pierre Kawak, Harshad Bhapkar, David S Simmons Since its discovery in the 1930s, nanoparticle-filled rubber has found wide ranging application for its reinforced toughness compared to neat rubber. Despite being in use for almost a decade, our understanding of the physics behind this reinforcement is incomplete and many active competing theories exist. All theories formulate molecular-scale mechanisms for the origins of enhanced energy dissipation due to the presence of nanoparticles within a polymer network, which leads to a better mechanical response. Here, we describe our novel approach to addressing these theoretical controversies. By leveraging molecular dynamics simulations of filled rubber and their response to shear, we identify locations of enhanced energy dissipation within the melt. These results discriminate between the roles of the various proposed mechanisms of enhanced dissipation in filled rubber. Elucidating the physics of reinforcement of filled rubber will lead to better-informed manufacturing that selects for desirable properties in many important industries, such as better toughness with high electrical conductivity for energy storage. |
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G00.00181: Computationally predicted electronic structure of β-Ga2O3(001)/NiO interface Cheng-Wei Lee, Andriy Zakutayev, Vladan Stevanovic β-Ga2O3 is a promising ultrawide bandgap oxide (Eg ~4.9 eV) due to its excellent n-type performance and the fact that high-quality single crystal can be grown from melt. However, no p-type doping has been realized for β-Ga2O3, preventing homoepitaxial p-n junction. Instead, heterojunction is needed and β-Ga2O3(001)/NiO heterojunction was recently shown to have better rectifying performance than β-Ga2O3/Ni Schottky diodes. Experimental J-V curves indicate the existence of interfacial states but their identities remain unclear. We approached this with computational studies on atomic details and electronic structure and identified three technical challenges. First, building atomistic models for β-Ga2O3/NiO is non-trivial and we addressed it via the atom-to-atom structure-matching algorithm recently developed by Therrin et al.[1]. Second, common DFT-based methods fail to capture the electronic structure of the whole heterojunction correctly at the same time. In this poster, we will show how HSE06+U can simultaneously reproduce the respective band gaps of β-Ga2O3 and NiO. Lastly, passivating such end surfaces requires further considerations than tetrahedrally coordinated semiconductors. With these challenges addressed, we predicted the differences in band edges, which are very different from values estimated using the electron affinity rule. In addition, our findings reveal potential interfacial defects and provide the basis for future improvement on its rectifying performance. |
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G00.00182: Characterizing Strain in Graphene on Cu(100) Substrate with Raman Spectroscopy Tehseen Adel, Jacob Amontree, Xingzhou Yan, Zizwe A Chase, Renee Harton, Charlezetta E Stokes, Thomas A Searles, Katayun Barmak, James C Hone, Angela R Hight Walker Chemical vapor deposition (CVD) grown graphene offers superior carrier mobility and minimal defects compared to mechanically transferred graphene onto Si/SiO2 substrates. Yet the performance of CVD-derived graphene films can vary across an array of wrinkles, folds, and transfer-related contaminations. Raman spectroscopy is a highly useful non-contact and non-destructive means of characterizing graphene owing to the nature of its band structure which provides strong and unique features stemming from physical effects such as resonant processes and strong electron-phonon coupling. Here, we present a detailed Raman analysis of uniquely grown defect-free graphene on Cu(100) substrate via low-pressure CVD. We observe the blue-shift and narrowing lineshapes of the 2D and G bands, as well as their intensity ratio indicating the graphene monolayer. Furthermore, a compressive strain and significant coupling of the graphene to the Cu substrate are observed with multiple laser excitations. Additionally, Raman is also used to monitor copper oxide at defect sites. We perform a combined electro-optical measurements in aqueous solutions to estimate the electrical material properties of graphene on Cu(100). The outcomes of this study will be used to establish quantitative Raman-based metrics on strain-doping for documentary standards on Gr/Cu compared to epitaxial Gr and other large-scale growth methods. |
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G00.00183: Convenient confinement: Examining ion and water behavior near graphene and graphene oxide thin films Amanda J Carr, Seung Eun Lee, Sang Soo Lee, Ahmet Uysal Understanding ion distributions and water orientation near graphene and graphene oxide surfaces is relevant to a range of applications, including capacitive deionization, heavy metal separations, and improved membrane performance. In each of these applications, ions and water interact with a graphene or graphene oxide surface in the small region forming between the solid and bulk liquid. Properties in this confined region greatly differ from typical bulk attributes, but experimentally probing interfaces is challenging, as most techniques are dominated by bulk signal. We experimentally characterize ion and water organization near both graphene and graphene oxide interfaces with molecular-scale resolution using a combination of surface-sensitive x-ray scattering and spectroscopy techniques. From these methods, we can fully describe the interface, including the structure of the graphene and graphene oxide films themselves, ion adsorption, and water orientation. These studies reveal the fundamental science underpinning downstream separation success. |
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G00.00184: Breakdown of Soft Anharmonic Phonons Heralds Fast Ionic Diffusion in Lithium Argyrodite Jingxuan Ding A fundamental understanding of the atomic structure and dynamics enabling fast ionic transport in solids is essential for the development of next-generation solid-state electrolytes (SSE). Focusing on the promising SSE candidate Li6PS5Cl with argyrodite structure, we resolve the coupling between fast diffusion of Li+ and vibrational dynamics of the host framework through extensive inelastic and quasielastic neutron scattering measurements, combined with machine-learned molecular dynamics (MLMD) simulations based on first-principles data. Our results establish that host lattice vibrations enable an order-of-magnitude increase in Li+ diffusivity at ambient temperature. Our experiments and simulations both show a clear overlap and interplay of hopping dynamics and vibrational frequencies in the terahertz regime, with a continuous spectral evolution from harmonic phonons to strongly anharmonic overdamped vibrations, and fast Li+ diffusion. We identify the key degrees-of-freedom enabling fast Li diffusion as low-frequency dynamics of PS43- polyanions, which are distinct from the commonly assumed "paddle-wheel" scenario. Bringing together neutron measurements and large-scale MLMD simulations, our results build a "beyond phonons" picture of complex atomic dynamics in SSEs in terms of overdamped spectral functions. These results offer microscopic insights into the mechanism of fast Li+ diffusion in lithium argyrodites and provide guidance for the design of future SSE materials. |
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G00.00185: Ionization and conformation consistency in weak polyelectrolyte solutions Alejandro A Gallegos, Jianzhong Wu, Zhen-Gang Wang The charge-regulated behavior of weak polyelectrolytes due to the solution pH and local chemical environment is advantageous for applications in smart systems to achieve specific functions such as targeted drug develiery and controlled release. Unfortunately, a quantitative description of such behavior remains challenging due to the inherent coupling in the polymer's ionization and conformation resulting from the long-range intrachain correlations. In this poster, we present a framework to self-consistently treat the ionization and conformation of weak polyelectrolytes in the bulk solution as well as near an interface. In addition, we focus on the influence of solution conditions on the inter- and intrachain correlations. |
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G00.00186: Reactive Bottom-up Coarse-Grained Model for Hydrated Protons Jaehyeok Jin Proton transport plays a critical role in many areas of chemistry, physics, biology, and materials science. Since proton transport occurs at a wide range of spatiotemporal scales, from the quantum to the mesoscopic levels, it is an intrinsically multiscale phenomenon. Yet, developing a high-fidelity multiscale model for hydrated protons is a challenge and currently limited to the atomistic level due to reactive bonding from explicit proton shuttling. This work aims to greatly extend the investigation of hydrated protons across much larger and longer scales by developing a rigorous bottom-up coarse-grained model to recapitulate structure and dynamics at a reduced level. The unique structural correlations arising from the hydronium cation can be captured by introducing internal states to the coarse-grained sites derived from quantum mechanics. A systematic design principle will be presented for determining internal states. To correctly capture the dynamics of hydrated protons, the average medium friction coefficient was predicted under Markovian limits. Our new Hydronium Ultra-coarse-grained Model with Improved Dynamics (HUMID) can faithfully capture structural and dynamical properties, including diffusion and hydronium time correlation functions with a speed-up factor of 500. As the first of its kind, this model can serve as an exciting foundation for studying mesoscale phenomena governed by proton transport and provide design principles for general reactive CG models with complex dynamics. |
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G00.00187: Building an Undergraduate Laboratory Course in Quantum Technology Mary Fries University of Massachusetts Boston (UMB) recently launched a four-course undergraduate Quantum Information Certificate program for students from across disciplines and industry professionals interested in learning about quantum information science (QIS). We are redesigning the fourth course in this sequence as laboratory course in superconducting quantum technology, making use of our existing on-campus nanotechnology makerspace and our new dilution refrigerator measurement system for quantum device characterization. This course is unique in that it will provide undergraduate students access to equipment that in other QIS education programs is generally reserved for graduate or faculty research. |
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G00.00188: Learning physics by experiment: IX. Entropy Saami Shaibani The creation of a molecule requires the constituent atoms to be in the right place at the right time. The factors involved in this become increasingly more challenging as one progresses from simple molecules to organic molecules, which are necessary precursors to cells. Some insight into the temporospatial aspects involved in even the simplest of building blocks of living matter is provided in this study by examining an intentionally primitive example with equal numbers k of only two types of particle. The statistics for arranging an initially random state of these particles into a highly-ordered configuration are determined, and the number of trials n required to produce at least one instance of this at a given threshold of observation p is also computed. Values obtained from such calculations begin with the case of 2k = 40 (cf. atoms in nucleotides), which has n = 109 to 1011 for p = 0.01 to 0.99, respectively. For more complex molecules where 2k = 100 (and 200) might apply, n = 1027 to 1029 (and 1056 to 1059) for the same p. Results of physical experiments and virtual simulations conducted for small k agree closely with analytical values. An account of the instructional approach for presenting the above material to students is included, with an emphasis on ab initio methods. |
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G00.00189: PHYSICS EDUCATION
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G00.00190: Design, Construction and Testing of Solar Concentrators for Solar Energy Experiments Dan Fauni, Roberto C Ramos Undergraduate research experiments were performed with the aim of building, testing and and optimizing luminescent solar concentrators as well as designing a Learning Module for a Summer Physics Camp based on results. A luminescent solar concentrator (LSC) is a transparent piece of plastic or glass with fluorescent dye or quantum dots embedded or painted on it. The dye absorbs incident light and then fluoresces creating a glow that propagates by total internal reflection (light entering the panel bounces between the faces) to the edge of the sheet where the light is absorbed by a narrow solar cell. This technology is promising because it allows a large collecting area of virtually transparent glass with a comparatively small area of expensive solar cells. In this work, the base material for our LSC consists of several rectangular pieces of clear and colored transparent acrylic. Using diamond scribes, solar cells were carefully diced and connected to line the edges of the acrylic. The output current and voltage of the solar cells were messured using digital multimeters to calculate power output. Measurements under controlled intensities of light were made using different colors of acrylic sheets and the use of different dyes to add color to clear sheets and the results compared. Results of these experiments will be discussed. A Learning Module based on this work and used as a component of solar-energy experiments in a summer physics camp for middle schoolers is also presented. |
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G00.00191: Investigating students' fluency with quantum ideas in the context of interaction-free experiments Cecilia E Ochoa, James K Freericks, Justyna P Zwolak, Leanne Doughty This research analyzes the effectiveness of two massive open online courses (MOOCs) offered by Georgetown University via edX, Quantum Mechanics (QM) and Quantum Mechanics for Everyone (QME). The QM course was designed for undergraduate physics majors and teaches quantum mechanics using operators in a representation-independent formalism. QME was created for those without a physics background and focuses primarily on conceptual understanding. |
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G00.00192: Integrating Imaging Physics Into Undergraduate STEM Education Bethe A Scalettar, James R Abney Physics is a notoriously challenging subject that plays a critical and ubiquitous role in our lives. Undergraduate educators thus need new approaches that will encourage college students to study physics. |
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G00.00193: OUTREACH AND ENGAGING THE PUBLIC
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G00.00194: A World of Women in STEM: An Online Learning Platform Taylor Contreras, Madelyn J Leembruggen Women and gender minorities have always been key contributors to the development of science, technology, engineering, and mathematics. Despite this long history of engagement, at every level of education, there is attrition of young people from underrepresented groups who lose interest in STEM topics due to unengaging content, lack of role models, active discouragement, or any other number of unseen factors. This so-called "Leaky Pipeline" is a well-established challenge to representation, inclusion, and retention of ethnic and gender minorities and women in the STEM fields. A World of Women in STEM (WOW STEM) is a free resource that addresses this issue by providing accessible and engaging blogs, videos, and activities that highlight the lives and science of women in STEM. WOW STEM contributors are graduate students, undergraduates, and early-career professionals in the STEM fields who are passionate about sharing their love of STEM with the world. Our content is designed specifically for girls in 7th-10th grade, when students begin to differentiate their interests, choose their own classes, and develop their sense of self-efficacy and belonging. This is also an education level that is largely ignored in most science communication efforts. WOW STEM fills this outreach gap, provides diverse STEM role models, and inspires curiosity in young women and gender minorities. |
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G00.00195: Nevada National Security Site involvment with Minority Serving Institution Partnership Program Sanjoy Mukhopadhyay The article elaborates the collaborative involvement of the Nevada National Security Site (NNSS) with Nuclear Security Science and Technology Consortium (NSSTC) for Minority Serving Institution Partnership Program (MSIPP). The MSIPP is a research-based experience for students who are traditionally underrepresented in Science Technology Engineering, and Mathematics (STEM) education. MSIPP is designed to build a steady pipeline between the U.S. Department of Energy facilities and national laboratories and minority-serving institutions in STEM disciplines, and bring a heightened awareness of NNSA plants and laboratories to institutions with a common interest in STEM research fields. |
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G00.00196: PUBLIC POLICY
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G00.00197: How the National Science Foundation Office of Inspector General Promotes Research Integrity Aaron Manka Among its duties, the National Science Foundation (NSF) Office of Inspector General is responsible for helping ensure the integrity of research programs at NSF. We investigate allegations of research misconduct (plagiarism, falsification, and fabrication) in NSF proposals and awards. We handle allegations of conflict of interests and violations of the confidentiality of NSF’s merit review to ensure the integrity of that process. We also investigate allegations of retaliation against whistleblowers. |
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G00.00198: ENERGY RESEARCH AND APPLICATIONS
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G00.00199: Magnetic and thermoelectric properties of Bi, Cu double-substituted La1-xSrxCoO3 Divya Prakash P Dubey We present the results of a comprehensive investigation of electrical and thermal transport properties and their magnetic correlations in polycrystalline Bi substituted La1-xSrxCoO3. The La1-xSrxCoO3 system is well studied for the electronic, thermal and magnetic phase separation properties which is key to improve the thermoelectric efficiency of the material. The 5% substitution in La1-xSrxCoO3 have peak of ZT at RT along with reversal of nature of charge carrier from p-n type around 290K make this system interesting for thermoelectric investigations. The choice of Bi substitution in this system has been made due to its high atomic weight and ability to increase S and hence in improvement of thermoelectric figure of merit keeping in mind. The effect of various spin state transitions due to the change of valence state of Co3+/Co4+ ions associated with the oxygen vacancies along with the effect of Bi-substitution on the structural, thermal transport, and electronic properties of LBSCO sample has been investigated thoroughly using x-ray diffraction, scanning electron microscopy and x-ray photoemission spectroscopy. More interestingly an anomalous feature observed in dielectric, resistivity and Hall measurements across the 50K that is associated with change of the nature of charge carrier, further verified with Seebeck measurements. At higher temperature the transport behaviour governs by small polaron hopping whereas at intermediate temperature range () the variable range hopping dominates the transport properties. Below 50K the role of the phonon drag effect for the phonon mediated charge carrier transport is confirmed by the thermal conductivity and Seebeck coefficient variation with temperature at different fields. The specific heat analysis helps to extract the electronic and phononic contribution in transport properties that shows the phononic contribution is much higher in the transport. The thermoelectric figure of merit has also been calculated and it shows the Bi-substitution helps to improve the PF as well as ZT significantly in comparison to existing cobaltite choices. |
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G00.00200: Limits of thermoelectric performance with a bounded transport distribution Jesse Maassen Band engineering is an important strategy that seeks to tailor a material’s electronic and scattering properties to improve its thermoelectric (TE) performance. This effectively alters the material’s transport distribution (TD), which is the central quantity that determines the electronic conductivity, Seebeck coefficient and electronic thermal conductivity. This work theoretically derives what is the optimal bounded TD and its implications on the limits of TE performance. To maximize the figure-of-merit ZT and the power factor the ideal transport distributions are boxcar and Heaviside functions, respectively – the edges of which must be located at specific energies. The optimal power factor is simply limited by the magnitude of the Heaviside TD, and reaches ZT values between 4-5. The optimal figure-of-merit, which can approach the Carnot limit, is uniquely determined by a key quantity that is proportional to the TD magnitude and temperature, and inversely proportional to the lattice thermal conductivity. These results suggest two general approaches to enhance TE performance: identify or design materials with TDs that have large magnitude and that possess the ideal boxcar or Heaviside shape. This study can help guide the search for improved TEs by establishing practical upper limits on performance, and by providing target TDs to guide band and scattering engineering strategies. |
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G00.00201: Thermoelectric Properties of Delafossite CuCr1-xFexO2 (0 ≤ x ≤ 1) Mithun Kumar K Majee Understanding the different conduction mechanisms in electrical and thermal conductivity is the central key point for improving the thermoelectric property of a material. Besides, the typical parameters like carrier concentration, lower thermal conductivity for good thermoelectric materials, the effect of phonon/magnon drag, spin Seebeck effect, spin fluctuations can also be used as control parameters to improved thermoelectricity. It is known from literature that CuCrO2 has large Seebeck value of around 350 µV/K at room temperature [1]. With this knowledge in background, we attempt a systematic study of electrical, thermal conductivity, heat capacity and Seebeck coefficient of CuCr1-xFexO2 (0 ≤ x ≤ 1) series. Our results exhibit sufficiently large and complex Seebeck coefficient in 20 K ≤ T ≤ 380 K. The electrical conductivity reveals p-type semiconducting nature confirmed from Hall-effect measurement and Seebeck coefficient. At low temperature, the electrical conduction mechanism obeys 3D-variable range hopping and at temperature above 150 K, thermally activated Arrhenius nature is observed. Unlike, nonmagnetic Cu-based Delafossite, thermal conductivity is strongly affected by spin-phonon scattering in CuCr1-xFexO2 compositions. Heat capacity measurements were used to identify the Debye temperature (θD) for all the compositions. The data confirm short and long-range magnetic ordering temperatures near the transition temperature. Out of the different processes that contribute to the total Seebeck coefficient of these compositions, our results suggest the dominance of the phonon drag effect in enhancing the observed values in Cr-rich compositions. |
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G00.00202: Thermoelectric Modules for Low-grade Waste Heat Recovery Amin Nozariasbmarz, Bed Poudel, WENJIE LI, YU ZHANG, Shashank Priya Annually, over 60% of global energy consumption is rejected as waste heat. Recovering a fraction of the wasted heat provides a transformative impact on overall energy saving. Thermoelectric generators (TEGs) are environmentally friendly devices that can directly convert heat to electricity. TEGs are reliable for waste heat recovery and power generation applications. Recent studies have reported the conversion efficiency of TEGs up to 14% under laboratory conditions. However, the practical efficiency of TEGs used in an actual environment is less than a few percent. The performance of the TEGs is influenced by materials figure of merit (zT), temperature gradient, internal electrical and thermal contact resistances, external thermal resistance, and boundary conditions. Commercial modules are not typically designed for specific applications when the thermal resistance of the heat source or sink is high. Therefore, depending on the application, materials and module designs are required to maximize energy recovery. |
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G00.00203: Electron transport in CaF2: The importance of structural phases at calcium-anode interfaces Kevin Batzinger, Manuel Smeu Current electrolytes in calcium-ion batteries (CIBs) suffer from reduction-driven degradation caused by electron flow from the anode. The solid-electrolyte interphase (SEI) that forms on CIB anodes during operation stems the flow of electrons from the anode to the electrolyte, making SEI formation a self-limiting process. CaF2 is a common inorganic compound found in the SEI of CIBs, and is derived from salts in the electrolyte such as Ca(PF6)2. CaF2 can exist in crystalline, polycrystalline, and amorphous phases in the SEI, and as recent work has shown, different phases of the same compound can have vastly different electron conductances. Using the non-equilibrium Green’s function technique with density functional theory (NEGF-DFT), we find that amorphous phase systems enhance electron tunneling in thin CaF2 films by 1-2 orders of magnitude compared to crystalline CaF2, while polycrystalline systems show similar transport properties to crystalline CaF2. Through analysis of the decay constant and the low-bias conductance, we show that crystalline and polycrystalline CaF2 offer greater protection of the electrolyte than amorphous CaF2. This work will provide key insights into the rational design of SEI layers with low electronic conductivity for use in calcium-ion batteries. |
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G00.00204: Thermoelectric properties of new heterobilayers of Janus-type Noble-Metal Chalcogenides materials Mourad Boujnah Janus and non-Janus monolayers are one of the transformations of the 2D materials viz present an exceptional opportunity to control and manipulate their physical properties. Herein, we predict the two-dimensional of noble-Metal Chalcogenides (NMCs) materials A2B (A = Ag, Au and B = S, Se) heterobilayes (HtBLs) through first-principles calculations. The Ab initio molecular dynamics simulations demonstrate that these monolayers possess excellent dynamic and mechanical stabilities. According to that, a combination of Janus and non-Janus of NMCs monolayers (MLs) and HtBLs. High optical absorption of around 4.5×105 cm-1 and high anisotropic carrier mobility of ~105 cm2 V-1s-1 is observed, which indicates that they may shine in the next generation of electronic and optoelectronic devices. All of these explorations not only enhance the types of 2D materials but also provide a structural reference for designing new MLs on the molecular level. The band gap values of a and b phases calculated at the HSE06 level are between 1.35 and 3.70 eV. The calculated lattice thermal conductivity of Ag2S (about 0.57 W m-1K-1) is low while the electrical conductivities and Seebeck coefficients are high at room temperature. Thus, the properties of these combinations show a high potential for thermoelectric applications. |
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G00.00205: Modelling pulse discharge of hybrid cathode Li/CFx-SVO batteries using Multiphase Porous Electrode Theory Qiaohao Liang, Partha Gomadam, Prabhakar A Tamirisa, Martin Z Bazant Power sources of implantable cardioverter-defibrillators (ICD) require high energy density to ensure longevity and sufficient rate capability to provide high power pulses for treating abnormal heart rhythms. Such demands have led to the design of Li/CFx-SVO battery, which leverages the excellent energy density of carbon monofluoride (CFx) and power density of silver vanadium oxide (SVO) through the use of a CFx-SVO hybrid cathode. A single particle model based on porous electrode theory was previously developed for Li/CFx-SVO. However, it overlooked phase separation in SVO and reaction heterogeneity across particles, and was unable to accurately predict the transient voltage response during transitions from high to low currents. In this work, we present a computational model of Li/CFx-SVO battery based on Multiphase Porous Electrode Theory for Hybrid Electrodes (Hybrid-MPET). Hybrid-MPET allows us to model the phase separation in SVO particles and predict the evolution of reaction heterogeneities across an ensemble of particles under different current rates. Validated against experimental data, our Li/CFx-SVO model not only excels at predicting voltage-capacity behavior under constant current or constant load discharge, but also now captures and explains voltage over-recovery phenomenon observed after high power pulses. In addition, we discuss how Hybrid-MPET framework opens up opportunities to study the performance of hybrid electrodes in rechargeable batteries. |
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G00.00206: Thermal and Transport Properties of Novel Metal Oxychalcogenides for Energy Recovery Joe Willis, Katarina Brlec, David O Scanlon It is estimated that up to half of global energy input is lost to thermal processes.[1] Harvesting this waste heat and converting it into consumable, electrical energy is a viable route towards cleaner energy, and is made possible through the use of thermoelectric materials and the Seebeck effect. Historically, thermoelectrics contain heavy, toxic metals such as Pb, and are unsuitable for use in everyday society. The discovery of non-toxic, earth-abundant thermoelectrics is therefore highly desirable, enabling widespread improvements in energy efficiency and potential climate change mitigation. |
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G00.00207: Characterizing the Back-Contact Interface of Bi-Facial Poly-Crystalline CdTe Devices Using Transmission Electron Microscopy John Farrell Poly-crystalline Cd(Se)Te based thin film solar cells have shown to be competitive in terms of efficiency and cost of electricity production. Yet, the presence of hetero-interfaces in Cd(Se)Te structure and low minority carrier lifetime have limited the thin film devices from reaching their maximum theoretical efficiency of approximately 30 percent. The back-contact of CdSeTe devices has been identified as one significant limitation to increased device performance since no metal has been identified that has a sufficiently high work function to create an Ohmic contact with the CdTe absorber at the back-surface of the film stack. Here, we will explore novel back-contact film layers in an effort to overcome this energy band mismatch. Atomic-resolution imaging in a scanning transmission electron microscope (STEM) combined with electron energy-loss spectroscopy (EELS) and energy-dispersive X-ray spectroscopy (XEDS) are used to characterize these devices and to inform the production process. The goal is to identify the ideal atomic and electronic structures, as well as any interfacial diffusion of elements. |
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G00.00208: Probing Structural Disorder via Photothermal Deflection Spectroscopy Stephen L Johnson, Luke Schroeder, Sophia Harryman, Julian Tudor, Madison Kellione, Kiera Draffen, Syed Joy, Tareq Hossain, Kenneth Graham Photothermal Deflection Spectroscopy (PDS) is a technique that excels at measuring weak optical absorptions in thin-film samples. Such absorptions are typically the result of structural disorder, so PDS can be a powerful tool to probe the relative amount of disorder in materials. In this poster, we present PDS data aimed at measuring the relative level of defect states in photovoltaic materials such as perovskites and hole transport layers, and correlating those data with device performance and complementary forms of spectroscopy. |
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G00.00209: in situ Ambient-pressure X-ray Photoelectron Spectroscopy Study on Solid-liquid Interface Chemistry at the atomic scale for Electrochemical CO2 Reduction Haoyi Li
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G00.00210: Defect Identification in Organic Photovoltaic Devices Using Thermoreflectance Imaging liliana w valle Organic photovoltaics (OPVs) have many potential advantages over inorganic photovoltaic devices, including physical flexibility and ease of mass production. However, the widespread adoption of OPVs is limited by lower operating efficiencies and susceptibility to degradation in ambient conditions. In this project, we use thermoreflectance imaging, a high-resolution non-contact thermography technique, to locate and explore the physical origins of defects in OPVs. Thermoreflectance images of both commercially purchased InfinityPV solar cells and in-house fabricated, P3HT: PCBM-based organic solar cells show strong, localized regions of enhanced reflectivity, indicative of defects. We identify electrical shunts with radial heat spreading associated with the metal contacts, whereas other defects present as concentric rings with no heat spreading, suggesting a potential mechanical origin. This work illustrates the utility of thermoreflectance imaging as a tool for identifying and characterizing localized defects in organic solar cells. |
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G00.00211: Characterizing the Role of Fluoroethylene Carbonate (FEC) in Suppressing the Nucleation and Growth of Plated Lithium in Fast-Charged Lithium Ion Battery Systems Michael Bowen For decades, the high energy density, superior longevity, and low maintenance costs afforded by lithium ion batteries (LIBs) have made them a staple of the consumer electronics industry. However, shifts in large scale energy demands driven by booming electric vehicle and renewable energy markets have exposed the limitations of modern LIB designs. Specifically, transport limitation-driven lithium plating at the anode-electrolyte interface during fast charging, resulting in capacity fade, internal shorting, and the potential for thermal runaway, continues to inhibit the growth of these and other industries. This work focuses on the use of nondestructive, in situ synchotron hard X-ray microtomography (XRM) to study the influence of a promising electrolytic additive, fluroroethylene carbonate (FEC), on the nucleation and growth mechanisms of plated lithium in fast charged LIB systems. Through a bottom-up, data-driven approach, we study and compare the morphology, prevalence, and heterogeneity of plated lithium at the anode-electrolyte interface in non-FEC and FEC systems at the sub-micron scale to both quantify and explain the efficacy of this additive in improving the performance and safety of LIBs. As such, we develop a novel framework for systematically screening novel electrolytic mixtures to bolster and expand upon the insights offered by conventional ex situ approaches that can be readily applied to the research and development of other "alternative" LIB designs and architectures. |
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G00.00212: Diffusion and Lattice Dynamics in Na-based Superionic Conductors Hung-Min Lin, Jingxuan Ding, Mayanak K Gupta, Douglas L Abernathy, Luke L Daemen, Olivier Delaire The demand for next-generation all-solid-state batteries with higher energy density and improved safety motivates extensive efforts to develop superionic conductors (SICs) for solid-state electrolytes. Further, Na-based batteries could be attractive by virtue of the abundance of sodium. While several Na-based SICs have been discovered, the key atomistic processes enabling the fast Na ion diffusion remain poorly understood. Combining neutron scattering and advanced materials simulation, we performed detailed investigations of the interplay between fast Na diffusion and host lattice dynamics in Na3SbS4 and Na3SbSe4. These compounds crystallize in a tetragonal phase at low temperature and upon warming transform into a superionic cubic phase, with ionic conductivity of order of ~10-3 S cm-1. Our inelastic neutron scattering measurements reveal a strong spectral weight transfer from low-energy phonons to diffusive dynamics in the superionic phase, indicating that low-energy anharmonic phonons can be seen as precursors of ionic hopping. Our phonon dispersion simulations support this view, and identify strongly anharmonic transverse acoustic modes near the H point, involving coupled Na hopping attempts and SbX4 tetrahedra dynamics. These results suggest that soft anharmonic phonons could play an important role in enabling fast Na diffusion in both Na3SbS4 and Na3SbSe4. |
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G00.00213: A fully self-powered cholesteric smart window actuated by droplet-based electricity generator Mingmei WANG, Yuchao Li, Zuankai Wang Self-powered smart windows are highly attractive for the development of energy-efficient buildings system, owing to its superior capacities in regulating the energy and information exchange between indoor and outdoor environments. Although immense achievement has been made in the self-powered cholesteric liquid crystal smart window (CLC-SW) based on triboelectric nanogenerators (TENGs), such a self-powered manner is limited by some challenges such as the need of the continuous input of external forces, as well as unstable performance owing to inevitable mechanical abrasion of TENGs surface. Here, we develop a fully self-powered cholesteric LC-SW by leveraging droplet-based electricity generator (DEG) as spontaneous and sustained energy reservoir, in which DEG has superior capacities to harvest ceaseless energy from ambient environment and circumvent any additional electrical power input. We demonstrate that DEG-driven CLC-SW exhibits a rapid response and high tunability in the transformation between the transparent state and the hazy state in a wide range of solar spectrum. Distinct from the conventional smart windows, both transparent and hazy modes of DEG-driven CLC-SW can be self-sustained for a long time, and also be reversibly switched by the gentle mechanical pressure-loading. The DEG-driven smart window developed in our work can also find some applications such as indoor temperature modulation and privacy information protection. |
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G00.00214: Investigating microstructure evolution of Mg-ion battery cathodes with simultaneous heating and electrochemistry in-situ microscopy Yingjie Yang, Robert F Klie Barriers to lithium-ion battery development, such as the limited energy density of Li-ion batteries and the scarcity of Li, have led to great interest in exploring multi-valent ionic batteries containing earth-abundant intercalation elements, such as magnesium or calcium. Reversible intercalation of Mg2+ ions is a crucial part of constructing a stable battery, which, when combined with high capacity, charts a promising pathway towards high performance and future designs of Mg-ion batteries. High levels of reversible Mg2+ intercalation have been reported in α-V2O5 by cycling assembled cells at an elevated temperature of 110°C, the benefit of which is retained at room temperature. The ex-situ experiments demonstrate that α-V2O5 can intercalate at least one mole of Mg2+ reversibly at 110°C, as opposed to <0.6 moles at 25°C. The capacity of the α-V2O5 is increased 20-fold, matching the performance of Li-ion batteries. Structural changes accompany this increase in electrochemical performance; the morphology of the α-V2O5 powders drastically changes from platelets to delaminated layers, and spectroscopy of Mg content change echoes the electrochemistry. |
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G00.00215: Effect of Cr and La doping in the physical properties of Aurivillius Bi5Ti3FeO15 Omar A Salas, Harikrishnan S Nair, Krzysztof Gofryk, Firoza Kabir Lead-based materials are the most used piezoelectric ceramics due to their high efficiency. Unfortunately, lead is toxic to humans and other living beings. There is currently an interest in layered ceramics which show a large piezoelectric effect at room temperature. This project studies layered Aurivillius perovskites of the form Bi4Bin-3Ti3Fen-3O3n+3 where n = 4. There is also interest in these compounds as they might present multiferroicity at close to room temperature. In this work, we study three Aurivillius perovskite compounds Bi5Ti3FeO15, Bi4LaTi3FeO15, and Bi5Ti3Fe0.5Cr0.5O15 to understand the effect of doping the Bi-site with La and the Fe-site with Cr. We have prepared our samples using solid-state methods. Synchrotron X-ray data indicate a joint space group of A21am for all three compositions. Using energy-dispersive X-ray analysis we confirm that our samples are near-stoichiometric. The magnetic properties show an antiferromagnetic nature of the magnetic ground state. In this poster, we will present the results from the structural and magnetic characterization of the three Aurivillius compounds. |
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G00.00216: Ecological Network Analysis of State-Level Energy Consumption in Maryland, USA Graham Hyde Renewable and clean energy sources are being integrated into the United States’ energy industry to mitigate climate change effects, creating a more complex network of energy production, distribution, and consumption. This study defines the state of Maryland’s energy industry as a network of producers and consumers and analyzes the network’s characteristics by using ecological network analysis (ENA), an tool for identifying a system’s indirect effects. The energy industry within Maryland is analyzed over a nine-year time span to understand how its evolution is influencing the network’s characteristics. Maryland’s renewable portfolio standard (RPS) for the year 2030 is then simulated by adjusting energy sources according to energy trends and related state policy. Results from the ENA over the nine-year period of 2010–2019 indicate that the energy industry is highly linear. Typical cycling indices range from 5–15% in ecological energy flow models, cycling indices in this study ranged from 0.007% to 0.0082%. Maryland’s energy industry in the year 2030 is simulated and displays increased cycling because renewable sources typically feed the electricity sector for energy distribution, increasing indirect pathways within the system. The percentage of electricity generated by renewable energy increased from 9.71% in 2019 to 50% in 2030, as mandated in the RPS. Network analyses here emphasize the large gap between Maryland’s current energy infrastructure and what is necessary to meet its renewable targets in 2030. Analyses indicate that a more uniform distribution of energy to consumers may increase efficiency in modern energy industries. |
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G00.00217: Suppression of shuttle effect of Na-S batteries using monolayer and bilayer Ti3C2F(OH) MXene as an anchoring material Saba Khan Sodium sulfur batteries that operate at room temperature (RT) have been proposed as a solution to handle large scale energy storage applications. This popularity has been fuelled by the remarkable energy storage density and by the abundance of the electrode materials in the Earth’s crust. However, one of the main challenges faced by RT sodium sulfur batteries is the shuttle effect caused by the six sodium polysulfides (NaPS) Na2Sn, n = 1–8, which when dissolved in the electrolytes (namely DOL, DME), largely hinder the capacity of the battery. Therefore, the electrode interface plays a crucial role in controlling the shuttle effect. The present work focusses on realistic DFT modelling of suppression of shuttle effect by using 4x4 samples of single and bilayer Ti3C2F(OH). The bonding between the NaPS and the monolayer Ti3C2F(OH) is stronger than the NaPS-electrolyte interaction. The strength of bonding increases as we move to the bilayer Ti3C2F(OH) structure. The strength of the interaction can be attributed to the significant charge transfer from the Na atoms to the functional groups (F/OH) as assessed by Bader charge analysis. The NEB studies demonstrate the lowering of the dissociation barrier of an Na2S molecule on the surface of Ti3C2F(OH) to 0.835 eV from 2.44 eV (for isolated Na2S) thereby facilitating accelerated electrode kinetics and higher utilization of sulfur. |
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G00.00218: Electron microscopy studies of aqueous Zn-ion battery reaction mechanisms Zachary R Mansley, Daren Wu, Nahian Sadique, Lei Wang, Amy C Marschilok, Kenneth J Takeuchi, Esther S Takeuchi, Yimei Zhu The high theoretical capacities, safety, and low cost of aqueous Zn-ion batteries (ZIBs) with MnO2 cathodes make them attractive alternates to Li-ion batteries; however, details regarding the dominant energy storage mechanism remain under debate. Manganese oxide materials hold complexity for characterization due to the multiple polymorphs that the material can adopt including a variety of layered as well as tunneled structures. Further, the fundamental building block of the materials is based on manganese centers surrounded by oxygen typically in an octahedral arrangement. |
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G00.00219: Testing and Modeling Passive Daytime Radiative Cooling Devices Genevieve C DiBari Passive Daytime Radiative Cooling (PDRC) is a phenomenon that enables a surface to cool below ambient temperatures when exposed to solar radiation without the input of an external power source. Potential applications include reducing the need for air conditioning in hot climates. This project aims to model, fabricate, and test PDRC devices. These devices are designed to reflect the majority of incoming solar radiation; their emissivity is tailored to emit most of their thermal radiation in the atmospheric window such that the devices exchange heat with deep space. Our initial test devices are fabricated by depositing a thin layer of thermally evaporated silver onto a rigid substrate made of silicon or fused silica. The top layer is a roughly 500 microns thick coat of polydimethylsiloxane (PDMS), for which the emissivity is well matched to the atmospheric window in the infrared. Under summertime rooftop conditions in southern California, we have demonstrated that these devices can cool to 3-degrees Celsius below ambient temperature and to 20-degrees below the temperature of uncoated control samples. The experimental work is accompanied by a power balance model that quantifies the expected cooling of a device, given measured reflection, transmission, and absorption spectra. |
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G00.00220: Effect of nitrogen ligand type on 3d orbital level rearrangement of cobalt single atom catalysts Taeyoung Jeong, Joonhee Kang, Byung-Hyun Kim, Myeongjin Kim Transition metal single atom catalysts have recently emerged in acid oxygen evolution reactions (OER) due to their maximum atomic efficiency and high durability. Herein, we report a 3d orbital level rearrangement in square planar symmetry according to the ligand type of a cobalt single atom catalyst. We fabricate cobalt single atom catalyst supported on pyrrole type nitrogen doped crumpled graphene (Pyrrolic CoN4-CG) for acidic OER and it shows orbital rearrangement phenomenon because of their longer Co-N bond distance than pyridine type CoN4 sites. When pyrrole type nitrogen is introduced as a ligand of a cobalt single atom catalyst, the degree of oxidation during OER reaction is much greater than when pyridine type nitrogen ligand is introduced, which is confirmed by Operando X-ray absorption spectroscopy measurements. In addition, the reduction of OH- adsorption energy according to the orbital level rearrangement of Pyrrolic CoN4 and the change in the rate determination step are revealed by density functional theory calculations. |
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G00.00221: Suppression of irradiation effects in Fe-doped silicon Schottky diodes Joseph O Bodunrin, Sabata J Moloi In this study, the suppression of irradiation effects of Fe-doped silicon diodes was studied. Two sets of silicon-based diodes (undoped and Fe-doped p-Si diodes) were irradiated with 4 MeV protons to a fluence of 1x1017 p/cm-2 and then characterized prior to and after irradiation using current-voltage (I-V) measurements. The first batch was undoped p-silicon (Si) Schottky diodes fabricated on Si material, while the second batch was Fe-doped p-Si diodes. The rate of decrease in reverse and forward current in the Fe-doped p-Si diode is less than that of the undoped p-Si diode, indicating that the effect of irradiation has been suppressed due to Fe-doping. The obtained results suggest that Fe-induced defects in Si have improved the radiation-hardness of Si material. Hence, Fe just like Au and Pt is a suitable candidate in a bid to improve the radiation-hardness of Si material. |
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G00.00222: Discrete trap-related Bulk-limited Conduction in Solid kyungmin ko, Dong-Hyeok Lim, Joonki Suh Herein, we propose a trap-related charge conduction model analytically describing the bulk-limited transport by re-interpreting the generation and recombination behavior modelled by the Shockley-Read-Hall (SRH) process. When the conduction mechanism is rather limited by trap states, the thermal velocities of the charge carriers in the SRH model can be replaced by their drift velocities for the drift-dominant condition. That is, the randomness of their motion (immediately after emission) can be treated with a "directional" motion along the applied field. The derived SRH-based trap-related conduction provides an intuitive yet rigorous analysis of the current densities considering both types of charge carriers. Our generalized model can thus be universally applicable to a range of electronic materials systems when occurring discrete trap-related conduction. |
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G00.00223: Defect Engineering of Second Harmonic Generation in Nonlinear Optical Semiconductors Pei Li Second harmonic generation (SHG) plays a key role in developing modern optical devices and quantum optics, as they can expand the wavelength range provided by common laser sources <!--[if supportFields]>lang=EN-US>style='mso-spacerun:yes'> ADDIN EN.CITE <span style='mso-element:field-begin'>style='mso-spacerun:yes'> ADDIN EN.CITE.DATA <![if gte mso 9]> |
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G00.00224: Room-temperature formation and identification of the three silicon vacancy charge states in CVD diamond Artur Lozovoi, Alexander A Wood, Zihuai Zhang, Sachin Sharma, Gabriel I López-Morales, Harishankar Jayakumar, Nathalie P de Leon, Carlos A Meriles The electrical charge state of point defects hosted in diamond has emerged as a promising resource for improved quantum sensing and information processing |
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G00.00225: Tailoring Conductivity of Layered TiS2-xSex Edwin J Miller, Luisa Whittaker-Brooks Increasing reliance on low-power computing technologies and large-scale energy storage is a driving force for the study of ion transport in materials. In this area, layered transition metal dichalcogenides have stepped to the forefront of materials development. Notably TiS2, which has seen past application in Li+ ion batteries, has again come into vogue due to its wide inter-lamellar spacing and intercalation properties. To tune the electronic properties of this material, we have developed a synthesis of TiS2-xSex species. We report an increase in lattice spacing and electrical conductivity with the increasing concentration of Se in the material. Additionally, the effect of Se dopant concentration on ion mobility is investigated. It is expected that varying chalcogen compositions in TiS2-xSeX species will affect Li+ ion motion due to varying the ion channel width. A tandem goal is to investigate the change in electrical conductivity that occurs with ion intercalation into TiS2-xSex species. An increase in TiS2 conductivity with intercalated Li+ ions has been observed; studying this property with the suite of TiS2-xSex materials synthesized will provide insight into the changes in band structure upon intercalation of Li+ ions. Results are expected to have implications for the development of lithium-ion batteries, as well as computing systems based on ion motion. |
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G00.00226: Volatile resistive switching of LiPON/Metal-oxide heterostructure Yu Shi, RABIUL ISLAM, Guoxing Miao Memristor or resistive switching memory (ReRAM) based on binary metal-oxide has been shown to be promising in the field of neuromorphic computing due to its non-volatile resistive switching behavior and CMOS compatibility. However, large operation current independent of device area limits its integration with transistors, as lower drive current is provided with transistor size shrinking down. Compared to conventional non-volatile memristor, metal-oxide based volatile memristor shows advantages in lower operating current and area dependence due to its interface-driven nature. In this work, LiPON/Metal-oxide heterostructure is fabricated to explore the influence of Li ion on the volatile switching behavior of metal-oxide memristor. It is found that intercalation of Li ions increases concentration of defects at metal-oxide interface as well as the mobility of ion migration, which improves the switching speed and volatile ON/OFF ratio. Temperature dependence test is conducted to evaluate dynamics of ion motion, corresponding model is also proposed. |
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G00.00227: Modeling rare earth metal alloying in wide band gap oxides Eric W Welch, Luisa M Scolfaro, Pablo Borges Substitutional Gd alloying (GdGa) in β-Ga2O3 is studied using hybrid density functional theory. Structural properties show a monotonic increase in lattice parameters, volume and interplanar spacing with increasing Gd content implying the lattice expands to stabilize the larger atom. Cohesive energy and formation energy calculations show monotonically decreasing energy for increased Gd concentrations, implying stability even for large concentration Gd alloying. Optoelectronic properties for Gd content up to 37.5% show a noticeable red shift across all properties, which reveals how Gd alloying may be used to tune Ga2O3-based devices without significantly modifying the atoms which contribute to photoexcitation/emission (band edges); this includes radiation detection applications where high chemical stability, and a large nuclear cross section are required. |
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G00.00228: Modulation of electronic properties of MoS2 nanoflakes: geometrical shapes and vacancy doping Suejeong You After the exfoliation of single-layer graphene, many attempts to make devices using low-dimensional materials have been made. Due to the intrinsically thin body of the materials, conventional substitution doping is no longer available. Instead of substitution doping, we present atomic vacancy doping. In this talk, we show size-dependent characteristics and effects of sulfur atom vacancies of monolayer MoS2 nanoflakes via numerical simulation. We study several types of flakes within the six-band tight-binding model. Vacancy position and concentration change the density of states of the system. Also, geometric shapes and the number of sites can affect electronic properties. By comparing the size and vacancy concentration of nanoflakes, we explain the correlation between in-gap states and vacancy rates. Since the density of states governs the charge transport, our results would give ideas for developing low-dimensional material-based devices. |
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G00.00229: INSTRUMENTATION AND MEASUREMENT SCIENCE
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G00.00230: Frequency and damping noise of atomic force microscopy cantilevers with optomechanically modified quality factor at low temperature Noah Austin-Bingamon, Binod D.C., Yoichi Miyahara Noise in the frequency and damping signals are key parameters in determining microscope performance in frequency modulation atomic force microscopy (FM-AFM). We present a study of noise in the frequency and damping signals of AFM cantilevers used in a low temperature FM-AFM system with fiber-optic interferometric sensing of the cantilever deflection [1]. Due to a strong optomechanical coupling between cantilever oscillation and the optical field, the quality (Q) factor and resonant frequency are both dependent on the optical cavity length (formed by the fiber-cantilever distance). A systematic experimental study was undertaken to determine cavity lengths with the best signal to noise ratio, as well as the influence of optomechanically enhanced Q factor on frequency shift and damping noise. An automated protocol was developed to scan the fiber cantilever distance and measure the Q factor, resonant frequency, and frequency noise at each position. A digital phase-locked loop based self-excitation system was used to drive the cantilever oscillation and measure the frequency and Q. Actuation of the cantilever oscillation was achieved via optical force [1]. The fiber position was scanned using a computer-controlled piezoelectric stick-slip motor. A python script was used to unify control of the system. |
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G00.00231: Single-fiber radiation-pressure technique for calibrating ultra-soft cantilevers with non-perfect reflectance Jae-Hyuk Choi, Heonhwa Choi, Minky Seo Ultra-soft cantilevers have played important roles for pushing the sensitivity limit in several areas such as magnetic resonance force microscopy for singe electron spin detection, dynamic force magnetometry for half fluxoid quanta observation, and so on. In this work, to determine their mechanical impedance, we developed the techniques of single-fiber radiation-pressure calibration as well as local reflectance and transmission measurement, applicable to various cantilevers even with micro-scale width or without perfect-mirror surface. From the optic fiber interference signal and analysis for 200 nm-thick silicon nitride cantilevers, we obtained the reflectance value of 0.35, much larger than its bulk value, which agreed with the estimation considering thin film effect and was also consistent with separately obtained transmission values. It reveals the radiation pressure's dependece on the thickness, suggesting optimal tuning of cantilever thickness. Radiation pressure modulation of femtonewton level was adopted in actuating the cantilevers for mechanical impedance determination, and the preliminary results are to be shown and discussed. |
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G00.00232: A Fully-Passive, Quasi-Zero Stiffness Vibrational Isolator for Cryogen-Free Scanning Probe Microscopy Maxwell Freeman We demonstrate a novel, fully-passive vibration damping system designed to isolate a scanning tunneling microscope (STM) from the low-frequency noise introduced by a cryogen-free refrigerator pump. The design uses thin flexures to create an operating region of quasi-zero stiffness (QZS), effectively lowering the resonance frequency of the isolator into the sub-Hertz range and achieving < 1pm vibrational noise levels at the pump resonance frequency. The system is robust against cryogenic temperatures, and is compact enough to fit inside a dilution refrigerator, facilitating cryogen-free, low-temperature scanning probe microscopy (SPM). |
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G00.00233: Custom Piezo Stack Fabrication for Scanning Probe Microscopy Jasleen Kaur Piezoelectric actuators are composed of precision ceramic materials that convert applied voltage directly into linear motion by physically deforming in the presence of an electric field. The high displacement precision, large force generation, and fast response time of piezoelectric actuators make them crucial to various applications in nanotechnology and precision engineering. For example, a scanning probe microscope (SPM) typically employs stacks of shear piezoelectric plates to translate a tiny sensor across a macroscopic distance to approach a sample. Although prefabricated piezo stacks are commercially available, they are typically costly to customize. Here we describe a streamlined laboratory procedure to reliably fabricate piezo stacks from soft lead zirconate titanate (PZT) piezo ceramic plates. We designed a custom alignment fixture, which can be easily modified to fabricate stacks of varying sizes, to improve the efficiency and reproducibility of stack construction. We glue each plate sequentially, to minimize instability and misalignment throughout the fabrication process. Furthermore, we use interlayer copper mesh and EPO-TEK® H20E silver epoxy to ensure robust electrical attachment and stack height uniformity. |
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G00.00234: Three-dimensional mapping of the magnetic field using near-field scanning microscopy. Juan M Merlo-Ramirez, Rafi Ettinger-Finley Near-field scanning optical microscopy (NSOM) is a fairly mature research area which has allowed the discovery of very exciting phenomena [1]. Interestingly, the light intensity detected while raster scanning the sample surface is mainly the total electric field of the interactions at the close proximity. Although some approaches have been developed the three-dimensional mapping of the electric field at the near-field [2], there is still missing a reliable way to map the components of the magnetic field. In this sense, we present a novel approach for the detection of each component of the three-dimensional magnetic field. We demonstrate that our instrument is able to reproduce well-known theoretical results and opens the possibility to a new way of mapping the full electromagnetic field. |
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G00.00235: Experimental Applications using Oxford Instruments’ Superconducting Magnets Limeng Ni In this work, we show experimental applications of three superconducting magnet systems. |
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G00.00236: Development of a user-friendly time resolved scanning transmission x-ray microscope at the Advanced Light Source Hendrik Ohldag, Thomas Feggeler, Matthew A Marcus, Richard Celestre, David A Shapiro Time resolved x-ray microscopy at a synchrotron allows researchers to investigate variation of the electronic structure of a material during chemical, structural or magnetic changes with picosecond time resolution. In this presentation we will presetn the status of such a microscope at the Adbvanced Light Source in Berkeley, CA (USA) and how this can be realized using a field programming gate array in combination with a fast point detector. A synchrotron is a pulsed x-ray source with pulse lengths between 50-100 ps. Using low jitter electronics and lock-in detection schemes we are able to suppress noise and drift that is common in a synchrotron environment so that we are able to detect small signals of the order of 10^{-5} whihc helps to distinguish events within a single x-ray pulse and reduces the temporal sensitivity to ~10ps. We will show results based on an existing setup, e.g. movies of spin waves in confined magnetic structures with a periodicity of a few ns, but also describe how this method can be extended to dynamical processes with longer observation times using state of the art FPGA technology. Time resolved measurements with high spatial resolution will be an important part of research at future x-ray sources like e.g. ALS-U |
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G00.00237: Terahertz Reflection Spectroscopy Lauren K Jones The study of light-matter interactions is key in providing fundamental information about the physics of artificial materials. The spectroscopic response of a material encodes properties of the ground state as well as of its excitations. This has been critical in the understanding of novel quantum materials; the further improvement of spectroscopic techniques will continue to be key in the exploration of novel states of matter. We have developed a setup for time-domain Terahertz (THz) reflection spectroscopy to complement the more traditional transmission experiments. The advantages of reflection are that it expands the measurement capabilities to metallic samples, it can distinguish between electric and magnetic-dipole excitations, and it can help determine the full THz optical tensor. |
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G00.00238: Solid-state high harmonic generation as a probe of electronic structure and dynamics in metal organic framework HKUST-1 Bailey R Nebgen, Ryan Murphy, Ezra Korican-Barlay, Jacob A Spies, Can B Uzundal, Jeffrey R Long, Michael W Zuerch Metal organic frameworks (MOFs) are porous structures consisting of metal centers and organic linkers known for their ability to adsorb molecules from gas and solution phases. In general, MOFs are electrical insulators, but conductive MOFs would have diverse applications as electrocatalysts, chemiresistive sensors, and battery electrodes. Stoichiometric loading of the pores with covalently-bound dye molecules can anisotropically increase the conductivity of certain MOFs such as HKUST-1. To understand the tunable conductivity of HKUST-1 and inform the future design of effective conductive MOFs, it is critical to understand the mechanism of electron transfer and how it is impacted by structure and conditions. These structure-function relationships are studied through solid-state high harmonic generation (sHHG), a process in which electrons undergo tunnel ionization into the conduction band followed by interactions with the periodic lattice potential and eventual recombination and photoemission. With the sensitivity to band structure, symmetry, and anisotropic conductivity that sHHG provides, it has been underutilized in studying structure-function relationships in widely applicable materials like conductive MOFs. In this study, it is shown that MOFs such as HKUST-1 undergo efficient sHHG which is simultaneously detected with photoluminescence (PL). The direction of maximum PL emission informs on the orientation of the lattice while individual harmonics exhibit anisotropic characteristics that correspond to specific symmetries within the structure. Loading HKUST-1 with different amounts of the dye TCNQ and using angle-resolved pump-probe sHHG can reveal the structural and charge transfer dynamics that lead to tunable conductivity while maintaining high surface area. Understanding the mechanism of conductivity in a highly porous MOF will inform the future design of diverse conductive MOFs for a wide variety of electrochemical applications. |
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G00.00239: Spectroscopic Study of Bi5Ti3FeO15 Aurivillius Compound for Multifunctional Applications Mariana Castellanos, Harikrishnan S Nair, Felicia S Manciu Due to their semiconducting, ferroelectric, and antiferromagnetic properties at room temperature and manipulative magnetic states, the functions of multiferroic ceramics were extensively investigated for various technological applications, including quantum controlling, signal processing, and information storage. However, much less attention has been dedicated to the compound potential as a gas sensor, particularly for harmful gases. The aurivillius Bi5Ti3FeO15 phase presented in this study was synthesized using the solid-state method and analyzed spectroscopically using confocal Raman and vacuum-based Fourier transform infrared absorption. If the development of a high-performance bismuth iron titanate for sensing applications is envisioned, these throughout investigations of the compound phonon modes, as well as of its constituents Bi2O3, TiO2, and Fe2O3, besides reveling structural changes, demonstrate the usefulness of these characterizations in estimating the quality of the material. |
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G00.00240: Laser-Induced Breakdown Spectroscopy of Cr:ZnSe Gain Media Deblina Das, Vladimir Fedorov, Dmitry Martyshkin, Sergey B Mirov Chromium-doped Zinc Selenide (Cr:ZnSe) crystals are the gain media of choice for middle infrared lasers operating over a 2-3.4 µm spectral range. We report on laser-induced breakdown spectroscopy (LIBS) study of Cr:ZnSe polycrystals prepared with different regimes of Cr diffusion for measuring the variation of Cr distribution and crystals stoichiometry. LIBS is a rapid, real-time analytical technique that analyzes the spectral emission from laser-induced plasmas enabling fast chemical analysis without sample preparation. The optical emission of Zinc-Selenium-Chromium (Zn-Se-Cr) plasma produced by LIBS is studied here. An experimental setup was designed using a Q-switched Nd:YAG laser operating at 1064 nm (up to 100 mJ per pulse at 20 Hz rep rate) and an Echelle spectrometer with an ICCD detector. The electron number density is measured using the Stark broadening method using the neural Zn I (481.05nm) line. In contrast, the electron temperature is estimated employing the Boltzmann plot method of several Zn emission lines. For applications where a sub-ppb limit of detection (LOD) is required, a combination of LIBS with laser-excited atomic fluorescence spectroscopy (LEAFS) enables superior sensitivity (sub-ppt). We will also discuss the integration of the LIBS system with LEAFS. |
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G00.00241: Development of a high brilliance laboratory SAXS beamline at NSF BioPACIFIC MIP for high throughput in-situ structural characterization Youli Li, Phillip Kohl, Miguel Zepeda-Rosales, Christopher Barcelon, Alvin Pan, Ryan Willat The development of a high brilliance, high efficiency laboratory based SAXS-WAXS (small and wide-angle x-ray scattering) beamline for high throughput characterization of biopolymers and nanostructures is presented. The instrument, incorporating the most advanced x-ray source and detector technologies, is developed for the BioPACIFIC Materials Innovation Platform (www.biopacificmip.org) for rapid discovery and speedy development of new high-performance materials. A 70keV liquid metal jet x-ray source provides the world’s brightest beam in a laboratory, and a 4 mega-pixel hybrid photon counting detector provides the highest data collection efficiency from weakly scattering samples. The optical design of the instrument features enhanced scatterless beam collimation for parasitic scattering suppression and a fully automated diffracted beam detection module housed inside vacuum. The sample environment provides capabilities for in-situ studies utilizing temperature, flow, and strain. A custom-developed graphical user interface (GUI) has been developed and optimized for rapid measurement turn around as well as versatility to suit a wide range of applications. Preliminary results on rapid characterization of bio-derived polymers and automated cellular structures have demonstrated a performance level comparable to a 2nd generation synchrotron beamline. Beamtime is available to the broad research community via a rapid access user proposal process. |
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G00.00242: Coherent Surface Scattering Imaging reconstruction with Pytorch autograd and multislice forward model Peco Myint, Ashish Tripathi, Miaoqi Chu, Jin Wang, Suresh Narayanan, Zhang Jiang Coherent Surface Scattering Imaging (CSSI) brings together conventional imaging techniques, such as lensless X-ray Coherent Diffraction Imaging (CDI), transmission-geometry ptychography and laminography, and a surface sensitive technique of Grazing Incidence Small Angle X-ray Scattering (GISAXS). CSSI will be the feature technique of the new 9-ID beamline of the Advanced Photon Source Upgrade. For image reconstruction purposes, we need a physical model that can reproduce complex GISAXS scattering patterns, such as dynamical scattering fringes that are observed near sample horizon. Distorted Wave Born Approximation (DWBA) cannot reproduce such dynamical fringes near the critical angle of total external reflection. On the other hand, multislice simulations compute wave propagations through objects one 2D slice at a time along the beam direction and are already widely used in transmission geometry electron microscopy and X-ray transmission experiments. The multislice formalism could also be applied to CSSI reflection-geometry setups and can successfully reproduce dynamical scattering phenomena near critical angles. This multilice formalism has been implemented in fast performing GPU codes which can do forward calculations of tens of micron-scale surface patterns in a few seconds. Here, it is discussed how backward propagation of the multislice model and Pytorch auto-differentiation tool enable us to do 3D image reconstructions in the form of CSSI-CDI using a single scattering image. |
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G00.00243: PELICAN –a Time of Flight Cold Neutron Spectrometer – Recent Scientific Highlights Dehong Yu, Richard A Mole The time-of-flight direct-geometry neutron spectrometer, Pelican, has been serving the scientific community for many years with excellent outcomes [1]. The Pelican instrument was designed to meet the diverse requirements of the scientific community from physics, chemistry, material science, to biology. A wide range of research fields is covered. These include crystal-field excitations, phonon densities of states, magnetic excitations for various multifunctional materials including high Tc superconductors, novel magnetic, thermoelectric, ferroelectric and piezoelectric materials; molecular dynamics in hydrogen-bonded and storage materials, catalytic materials, cements, soils and rocks; and water dynamics in proteins and ion diffusion in membranes. Polarized neutrons and polarization analysis option makes the full use of the neutron spin to study magnetism and to separate the coherent and incoherent scatterings. To meet the demand of diverse user community, new sample environment equipment has been developed and commissioned including high pressure cell, in-situ light irradiation, fast dilution temperature cooling system and superconducting magnet. These new developments have significantly extended the instrument capabilities. |
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G00.00244: High-temperature Phonon Dispersion at the Nanometer Scale by Electron Energy-Loss Spectroscopy Andrew O'Hara, Benjamin Plotkin-Swing, Niklas Dellby, Juan Carlos Idrobo, Tracy C Lovejoy, Sokrates T Pantelides The advent of monochromated aberration-corrected scanning-transmission-electron microscopy (MAC-STEM) has led to spatially resolved and millielectronvolt-scale energy resolution in electron-energy-loss spectroscopy (EELS) of phonons. The versatility of MAC-STEM also allows for the trading of spatial resolution for momentum resolution, leading to measurements of phonon dispersions. Here, we report momentum-resolved EELS in layered, hexagonal boron nitride at three temperatures 300 K, 800 K and 1300 K across and beyond the first Brillouin zone. The EELS measurements allow the extraction of anharmonic effects in the phonon modes, reflected by meV-scale phonon energy shifts. Density-functional-theory calculations incorporating anharmonic effects in phonon self-energies are consistent with observed energy shifts and allow the identification of contributing mechanisms. Available phonon-EELS theories that treat a crystal as a collection of atoms fail to reproduce the EEL spectra at large momentum transfers and high temperatures. Umklapp processes are likely to be the dominant issue in the case of large momentum transfer. |
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G00.00245: Penumbral image source reconstruction with thick optics and uncertainty quantification Michael A Jaworski, David C Moir, Michelle A Espy, Sebastian Szustkowski X-ray inspection systems often utilize highly-penetrating photon energies to pass through high-Z, thick systems. The LANL Microtron facility makes use of a 10-20MeV electron beam and converter target to produce high-energy photons of similar energies for this purpose. The source size, while sufficient for current uses, has not been characterized in detail. Recent work by Bachmann [1] images a 10–20 keV source with the use of both pinhole-based direct imaging with penumbral imaging. For higher energy systems finite thickness objects. We analyze a series of radiographic images obtained on self-developing films and image plates examining the effects of finite opacity optics. A Bayesian analysis approach is used to characterize reconstruction uncertaintites, similar to work by Bardsley, et al. [2]. Initial estimates of the source size indicate a Gaussian-like source with a distribution width of 1 − σ ≈ 379 microns. [1] B. Bachmann, et al., Rev. Sci. Instrum. 87 (2016) 11E201. [2] J.M. Bardsley, et al., SIAM J. Sci. Comput. 34 (2012) A1316. |
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G00.00246: A Lower Limit on Controls Noise in LIGO's Suspended Optic Ian A Macmillan, Lee McCuller Since the first version of the Laser Interferometer Gravitational-wave Observatory (LIGO), suspended optics have proved vital to decoupling seismic noise from optical motion. In the 10-20Hz band, the control loop that steadies these optics introduces significant controls noise, which is amplified sensing noise. While this noise currently does not hinder LIGO's ability to detect gravitational waves, upgrades like frequency dependent squeezing incorporate more suspended optics which could benefit from lower controls noise. We model a new control system design using Kalman filters and modern optimal control methods to estimate the lower limit on the controls noise in LIGO's suspensions. Since controls noise is a limiting noise in other processes in the LIGO detectors, having a lower limit of this noise can inform how well essential processes, like LIGO's arm-length stabilization, can perform. We also look at how an improvement in the sensor array can improve the overall state estimation of the suspension and help to improve the controls design and decrease extraneous noise. |
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G00.00247: Planning and Simulating Neutron Spin Echo Experiments Piotr A Zolnierczuk High resolution neutron spin echo (NSE) spectroscopy is one of the most powerful techniques to study the dynamics of soft matter [1]. The SNS-NSE spectrometer [2] located at the BL-15 of the Spallation Neutron Source, Oak Ridge National Laboratory is the first, and to date, the only one “classic” NSE spectrometer installed at a pulsed neutron source. Typical applications of the NSE spectrometry are studies of molecular motions at the nano- and mesoscopic scale. |
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G00.00248: Multi-Frame Gated X-Ray Imager (MGXI) for Fast Hard X-Ray Imaging Mary Ann Mort The proposed multi-frame gated x-ray imager (MGXI) is a fast, hard x-ray imaging diagnostic for use in inertial confinement fusion (ICF) and high energy density (HED) experiments at the National Ignition Facility (NIF), such as Compton radiography and hot spot imaging. Individual MGXI component testing is happening in phases at Lawrence Livermore National Lab (LLNL) and the UC Davis Vacuum Microelectronics Lab. The Icarus2 hCMOS sensor was tested with a class 1 laser in both the high speed timing (HST) and manual shutter testing (MST) modes. Microchannel plates (MCPs) will be tested under vacuum with an electron gun and a simple photodiode array. MGXI has goals to image 10-100keV x-rays with 100-1000 ps temporal resolution in 2-8 frames and >5% detector quantum efficiency (DQE). |
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G00.00249: Investigating Chromospheric Activity from Mg II λ2800 in Stars Using Scattered Light Corrected NGSL Spectra from HST Tathagata Pal, Guy Worthey, Islam I Khan, Michael D Gregg, David R Silva Hubble Space Telescope (HST) observed approximately 556 stellar targets for the Next Generation Spectral Library (NGSL) using Space Telescope Imaging Spectrograph (STIS). NGSL currently contains spectra of 376 targets (corresponding to proposals GO9088, GO9786, and GO10222) with wavelength coverage from 0.2 < λ < 1 μm at λ/?λ ∼ 1000 (Gregg et al., 2006; Heap and Lindler, 2009). The G230LB grating of STIS, used for UV observations, scatters red light. In this work, observations corresponding to proposal GO13776 have been completely reduced which increases the number of stellar spectra in NGSL from 376 to 514. All spectra are also corrected for scattered red light following the prescription by Worthey et al. (2022). The Mg II λ2800 feature is a good indicator for chromospheric activity (Linsky and Ayres, 1978; Fanelli et al., 1990). It has been found in this study that MgII chromospheric emission dominates over photospheric absorption for (B-V)0 >1.0. This trend is seen for both giants and dwarfs, signifying no dependence of MgII emission on surface gravity. For stars with (B-V)0 <0, MgII photospheric absorption dominates over emission. Extremely hot stars ((B-V)0 <0) show neither absorption nor emission for MgII 2800. All cool stars (Teff<5500K) from NGSL are selected to verify the “basal” flux theory by Martinez et al. (2011) and a number of stars with flux lower than the anticipated “basal” flux value are found. No notable dependency is found for MgII 2800 magnitude on metallicity ([Fe/H]) for both dwarfs and giants. |
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G00.00250: Using 3D Printing in the Lab Rosa E Cardenas, IIeana Lane 3D printing is now more accessible than ever before. Its affordability has made it possible to create parts useful in multiple scientific capacities. The accessibility of these instruments in effect brings a machine shop to small universities where resources are limited and there is no access to the service from a machine shop. Parts created with commonly available stereolithography 3D printer are described for use with a cryogen free NMR. In addition to this, the advantages and disadvantages of the parts created with 3D printers have been studied. |
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G00.00251: Radiative modeling and cryo-engineering for LIGO Voyager prototype Radhika Bhatt The Laser Interferometer Gravitational-Wave Observatory (LIGO) is considering a near-future cryogenic upgrade (Voyager) to its current detectors to increase strain sensitivity. The Voyager upgrade will involve radiative cooling of 200 kg silicon test masses to 123K and the use of 2-um lasers for GW detection. The strength of radiative coupling is largely dependent on surface emissivities, which must be high enough to offset heating from high-power laser fields. The Mariner upgrade at the Caltech 40m interferometer aims to prototype Voyager technologies. We discuss efforts to model the radiative cooldown of 40m core optics, in order to inform optimal coating and shielding design choices for Mariner. We present an emissivity measurement setup to estimate and verify material emissivities within specification tolerances. The experiment uses a cryostat to cool samples to 123K and obtain temperature data. Robust estimates of emissivities and system parameters are achieved using Markov-Chain Monte Carlo (MCMC) methods. This work will contribute to the design of efficient radiative cooling for cryogenic interferometry. |
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G00.00252: MEDICAL PHYSICS
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G00.00253: In vitro evaluation of cobalt zinc ferrite nanoparticles for the SS-OCT imaging and simultaneous drug delivery in colorectal cancer Dhruba Dhar Swept-source optical coherence tomography (SS-OCT), a non-invasive imaging technique based on the backscattering property of biological tissues, offers an improved signal-to-noise ratio, higher imaging speed, and better resolution than the conventional spectral domain OCT. SS-OCT, however, provides limited penetration ability and contrast, which can be partially overcome by exploiting nanoparticles (NPs) as exogenous contrast agents to improve image contrast. Moreover, the utilization of NPs capable of being magnetically targeted to deep tumor regions for simultaneous drug delivery and imaging has also gained tremendous attention over the past few years. Thus, in this work, the feasibility of cobalt zinc ferrite NPs (CZFNPs) as an SS-OCT contrast agent was explored. In addition, due to the ferromagnetic nature of CZFNPs, these NPs were also exploited for the magnetically targeted simultaneous (along with imaging) delivery of 5-Fluorouracil in colorectal cancer tissue phantoms. To validate the imaging ability of CZFNPs, scattering coefficient and contrast-to-noise ratio calculations were done at different time exposures, while their drug delivery/anti-cancer potential was assessed using cell viability studies. Post analysis, a substantial increase in contrast and scattering coefficient was observed with time. Additionally, a significant site-specific killing of cancer cells was also achieved in comparison to the free drug. |
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G00.00254: Label-free nanoscale chemical mapping of intracellular structures George Greaves Imaging with nanoscale spatial resolution is of prime importance for understanding biology on an intracellular level, but optical diffraction sets a resolution limit which prevents this for standard optical microscopes. Specialist techniques such as super-resolution fluorescence and electron microscopy surpass this limit, but both require stains or labels to generate image contrast, which can be toxic, make quantification hard, and may even perturb sample biology. |
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G00.00255: Inverse Opal Photonic Crystals as Diagnostic Sensors Natalie Nicolas Inverse opals are self-assembled 3D photonic crystals with a unique potential for colorimetric diagnostic sensing of both soluble biomarkers and viral particles. Changes to their structural color due to the selective wetting of pores and subsequent change in the effective refractive index of the inverse opal can be used to easily visually distinguish between fluids with different physical properties, which can be indicative of disease states, or to determine the presence of bound particles. As the wetting point of the pores is determined by pore geometry and the contact angle formed with the testing fluid, these structures are highly customizable for use in different diagnostic systems. The colorimetric differentiation of fluids with nanomolar to micromolar concentrations of surfactants including bile salts is made possible by patterning the surface chemistry of an inverse opal with silanes of different hydrophobicities. Detection of viruses with an optical microscope has been enabled by observing the change in the wetting of a test solution into the structure due to the geometric change induced by the binding of a virus to the pore wall. By understanding how pore geometry and surface chemistry contribute to the interactions between inverse opals and fluids, we can more effectively utilize these structured materials for diagnostic sensing. |
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G00.00256: Theoretical calculation and experimental demonstration of differential heating for conductive nanoparticles in lossy biological media under radio frequency irradiation Nicholas J Rommelfanger, Kenneth Brinson, Zihao Ou, John E Bailey, Analiese M Bancroft, Carl H Keck, Guosong Hong Nanoparticles that strongly absorb radio frequency (RF) energy are desirable for techniques that require a wireless heat source deep within tissue, such as hyperthermia. While many studies have focused on the RF absorption of spherical metallic nanoparticles, opportunities afforded by high-aspect-ratio nanomaterials have not been sufficiently explored. We use the electrostatic approximation to calculate the relative-absorption ratio of metallic nanoparticles implanted in various biological tissues from 1 MHz to 10 GHz. We find that high-aspect-ratio prolate spheroids (approximating nanowires) offer powerful absorption of RF compared to the surrounding tissue, while oblate spheroids and spherical nanoparticles offer minimal relative absorption. These results inform our subsequent experiments with conductive carbon nanotubes (CNTs). Our sonication-free preparation preserves the high aspect ratio and local concentration of "pristine" CNTs. We demonstrate a 4.5-fold increase in heating of CNTs under 2 GHz irradiation compared to a saline solution, and we show localized differential heating of pristine CNTs injected into a tissue phantom. This work provides a generalized theoretical platform for determining the relative RF absorption of sub-wavelength particles compared to a tissue background. |
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G00.00257: The Physical mechanism of using NMR for cancer detection Donald C Chang As an early developer of using the NMR method for cancer detection, I would like to review the history of the development of this technique and the physical mechanism behind it. Today, the MRI (Magnetic Resonance Imaging) technology is a very powerful tool for detecting cancer development in a patient. Thus, it is important to understand how NMR measurements can differentiate normal cells from pre-neoplastic cells and cancer cells. In this talk, we will review the physical mechanism that allows the NMR measurement to distinguish between the normal cells, the pre-cancer cells and cancer cells. One key point is that the contrast of MRI image was found to be based on difference in nuclear relaxation times (T1 and T2) and spin diffusion rather than based on the concentration difference of cellular water. At present, there is still an active interest to understand the mechanisms behind relaxation time changes of water protons during cancer development. In this talk, I will review several possible physical mechanisms that could explain the relaxation time changes when cells are transformed from the normal state to the pre-cancer, and finally to the cancer state. |
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G00.00258: The physics of cancer recurrence and metastasis Robert H Austin, Yusha Y Sun, David Liao, Gonzalo Torga, Trung V Phan, Joel Brown, Emma Hammarlund, Sarah Amend, Kenneth J Pienta We frame cancer progression as state changes of small-n cancer cell communities that are relevant for evolutionary and physical processes during cancer recurrence and metastasis: poly-aneuploidy, heterogeneity, speciation, resistance, evasion, and intravasation or invasion. We propose the following state changes leading to metastatic cancer, somewhat speculatively in the order in which the states flow towards full-blown inoperable and highly resistant metastatic cancer. |
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G00.00259: Pharmacokinetics Data Analysis of Doxorubicin Drug to Examine Variability in Patient-Specific Drug Kinetics Blessing C Akah Pharmacokinetics-Pharmacodynamics (PK-PD), a model that integrates the time course effect of drug concentration with its pharmacological effect, is a useful mathematical tool in the preclinical development of oncology drugs; to understand and predict the pharmacological behavior of anticancer drugs. This study is on pharmacokinetics data analysis of the Doxorubicin drug to examine variability in patient-specific drug kinetics, using a model described by Young Choi et al. The proposed model employed a naïve pooled population-based PKPD modeling and revealed a higher contribution factor of Sor (PO) on overall tumor-growth inhibition than the co-administered Dox (iv) drug. |
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G00.00260: Fe@Ag-Matrix Magnetic Nanoparticles for Hyperthermia Cancer Therapy Marcos A Garcia, Siria L Jansen, Ahmed A El Gendy, Yohannes W Getahun, Valeria P Erives-Sedano, Jennifer N DeAlba Magnetic nanoparticles have garnered much attention due to their diverse usage in biomedicine such as MRI, drug delivery, and cancer therapy. Although iron oxide nanoparticles are often chosen, bimetallic nanoparticles have become an innovative approach to use in biomedicine. We have synthesized an Iron-Silver magnetic nanoparticle matrix using Iron-Sulfate and Sodium Citrate with Sodium Borohydride as a reducing agent. The time of injection of Silver Nitrate to the ferrous salt solution will give us different sized particles and different magnetic saturations. Using VSM we measured a magnetic saturation of 226 emu/g for an injection time of seven minutes. We tested the viability of the magnetic nanoparticles in hyperthermia therapy by inducing an alternating magnetic field to test their heating capabilities. The magnetic saturation values give an idea as to how dispersive the particles will be during the hyperthermia therapy. We have also functionalized the Iron-Silver magnetic nanoparticles using plant-based coating to add a layer of protection to the particles and increase their dispersive properties when used during treatment. We have also used the characterization techniques of XRD and SEM to analyze the crystal structure and size of the particles. |
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G00.00261: A Holographic Informational Quantum Model as the Human Mind Hassan Gholibeigian, Hassan Gholibeigian Every elementary particle includes Informational Quantum Potential (IQP) that receives its necessary information, processes, and uses its result (consciousness) for its next dynamic motion. A human also is composed of two matched wavy-like geometries (quantum fields) with two different boundary surfaces; first by his (her) elementary particles of his body, and the second by his elementary particles’ IQPs as a hologram that we propose it as the human quantum mind/psyche/soul. Quantum states (qubits) of the involved elementary particles of the first quantum field changes/increases by communication/thinking during the time. And the received packets of information by involved IQPs interact with each other and raises/deepens consciousness inside the hologram. This informational quantum holographic system is origin of emergence of human properties like consciousness, love, ethics, … and decision making for his behavior. The boundary surface of the hologram is not physical, but it is an imaginary mathematical shell according to Planck surface (Holographic principle). The boundary surface of the first quantum field is body’s skin. The boundary surface of the second quantum field (hologram) varies/increases continuously by increasing the communication of the involved particles with each other. |
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G00.00262: Core/Shell Superparamagnetic Nanoparticles and their Potential for Magnetic Hyperthermia Cancer Therapy Siria L Jansen, Marcos A Garcia, Yohannes W Getahun, Valeria P Erives, Jennifer N De Alba, Ahmed A El Gendy Due to the side effects produced by radiotherapy and chemotherapy on cancer patients, there has been a need in the world of biomedicine for an alternative option. Superparamagnetic nanoparticles (SMNPs) have been sought out due to their potential for hyperthermia treatment in which a magnetic field is applied to to heat up injected nanoparticles causing them to heat up. To be successful, magnetic nanoparticles must display high magnetism and good dispersion to allow for the heating potential of the nanoparticles to be reached and effectively kill cancer cells. Iron-oxide has been utilized thus far due to the cost efficiancy of the materials and the success in reaching their heating potential. One complication that arises with iron oxides in hyperthermia treatment is their lower magnetization levels which means there is difficulty at times to reach the optimized specific absorption rate (SAR) needed to effectively treat cancer using hyperthermia. In this work, we use a "bottom-up" approach where we use iron precursors to synthesize pure iron nanoparticles (FeNP's) with a gold core-shell surrounding the nanoparticle (Au@FeNP's). We used VSM, XRD, and SEM devices to assess the magnetization and structure of these nanoparticles. Due to the high magnetization and SAR of the superparamagnetic nanoparticles, as well as the x-ray diffraction values, there are indications of pure iron nanoparticles mixed with iron-oxide nanoparticles being produced. the results yielded varying magnetizations based on many factors such as nucleation times, chemical ratios, and the use of the pressure reactor. The most promising of our results show a high magnetization of 175.13 emu/g, while still remaining superparamagnetic. Through XRD analysis we have confirmed that our samples are composed of pure iron and gold with little impurities allowing for potential use in-vitro and in-vivo studies. |
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G00.00263: High Resolution Optical Recording of Bioelectric Signals Using Electrochromic Materials Burhan Ahmed, Kenneth Nakasone, Dana Griffith, Yuecheng Zhou, Erica Liu, Felix S Alfonso, Bianxiao Cui, Holger Mueller Studying electrical signals in biological cells is vital to advancing our understanding of biological phenomena. Non-invasive methods with high spatial and temporal resolution are essential for such studies; they can, for example, be used to uncover how a network of interconnected neurons transmits and processes information. Existing optical recording techniques, such as voltage-sensitive fluorescent probes, are already used to measure neuronal activity; however, these methods often suffer from photobleaching and phototoxicity and are therefore limited in their ability to monitor electrical activity over long periods of time. Electrochromic optical recording (ECORE) is a technique which uses the electrochromic properties of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) in order to study bioelectric signals. It represents a non-invasive and highly flexible method of detecting these signals while also enabling their long-term recording. Here, we report on our work to increase the spatial resolution of ECORE by incorporating a microscope objective lens into our setup. Improved spatial resolution will enable us to probe local regions of cells of interest and enable us to study these cells in further detail, complementing the benefits already presented by ECORE. |
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G00.00264: Ferromagnetic Resonance Spectroscopy, Micromagnetic Simulations and Scanning Transmission X-ray Microscopy as a toolbox for the characterization of magnetic nanoparticle ensembles Thomas Feggeler, Ralf Meckenstock, Detlef Spoddig, Benjamin Zingsem, Johanna Lill, Damian Günzing, Sebastian Wintz, Markus Weigand, Michael Winklhofer, Michael Farle, Heiko Wende, Katharina Ollefs, Hendrik Ohldag Magnetic nanoparticles are studied for applications from medical research towards high performance computing using magnonic excitations. [1-3]. The understanding of their dynamic magnetic properties is a crucial task to bring such particle ensembles towards the application state. A characterization toolbox for these demands is the combination of Ferromagnetic Resonance (FMR) spectroscopy, micromagnetic simulations and element-specific (Time-Resolved) Scanning Transmission X-ray Microscopy (TR-STXM) [4][5], using X-ray Circular Magnetic Dichroism (XMCD) as contrast mechanism [6]. Here we present the use of this toolbox for the dynamic magnetic characterization of Fe3O4 nanoparticles ensembles naturally grown by biomineralization within magnetotactic bacteria of the species Magnetospirillum Magnetotacticum (average particle diameter 40 to 50 nm). In-plane angular dependent X-band FMR spectroscopy shows a multitude of angular dependent resonances exhibiting magnonic band gaps and crossings, well resembled by micromagnetic simulations. With TR-STXM we demonstrate the phase resolved sampling of magnetization dynamics of a nanoparticle ensemble of the same species showing a resonant response uniform in phase and non-uniform in amplitude with < 50 nm spatial resolution supplemented by micromagnetic simulations in good agreement [4]. |
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G00.00265: Assessing nordihydroguaiaretic acid therapeutic effect for glioblastoma Jose A Guerrero, Felicia S Manciu, Kevin E Bennet, Marian Manciu Raman microscopy combined with computational analysis was used to detect structural changes in glioblastoma (GBM) biosignatures due to nordihydroguaiaretic acid (NDGA) administration. As a potential therapeutic agent, NDGA is a reactive oxygen species (ROS) scavenger and anti-oxidant. This phenolic lignan had positive effects on multi-organ malignant tumor reduction and inhibition. The current analysis of NDGA's effect on GBM human cells shows a decrease in altered protein content and ROS-damaged phenylalanine. The use of phenylalanine as a biomarker for differentiating across samples and evaluating NDGA's effectiveness is a new finding discussed here. The creation of lipid droplets and a decline in the altered protein content indicate that treatment with a low dosage of NDGA over long periods reduces abnormal lipid-protein metabolism. The knowledge acquired via this research is significant for comprehending both the positive and negative bio-effects of NDGA as a potential treatment for brain cancer. |
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G00.00266: QUANTUM INFORMATION
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G00.00267: Fast reset process of a superconducting qubit with autonomous feedback system Hyeok Hwang, Gyum Lee, Eunseong Kim Quantum algorithm requires a high-fidelity state reservoir, which can be achieved by a reset process of qubits. A natural relaxation of a qubit has been used without utilizing an artificial reset process, which demands unwanted extension of processing time as the relaxation time(T1) is longer. We demonstrate a new reset process in superconducting quantum circuits. The process uses qubit state-dependent cavity transmission and frequency conversion by a Josephson mixer. One cavity mode is designed to have a high transmission for a cavity-dressed state frequency at undesired qubit states. A transmitted pulse with the dressed frequency derives the undesired qubit states to Rabi-oscillate after the frequency conversion. The autonomous feedback process stops when a qubit has no population in undesired states. The reset pulse length depends on Rabi-oscillation frequency, not on the relaxation time of a qubit, so that a sub-microsecond reset can be available in our system although a qubit has a much longer relaxation time. |
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G00.00268: Advancements in surface preparation of 3D niobium cavities for quantum memories Nitzan Kahn, Engin Ciftyurek, Fabien Lafont, Serge Rosenblum 3D superconducting cavities are a promising platform for implementing long-lived quantum memories and for storing bosonic qubits with built-in error protection. Since the performance of the quantum memory strongly depends on the cavity's single photon lifetime, the improvement of the cavity's intrinsic quality factor is crucial. A primary cause of the degradation of the quality factor is the oxide layer that develops on the cavity's surface, resulting in photon loss induced by two-level systems in the oxide. We will present our efforts in tackling this oxide layer using various surface preparation methods. We show that these methods enable significant improvements in the cavity quality factor. |
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G00.00269: Dynamically corrected gates for a singlet-triplet qubit Xinxin Cai, Habitamu Walelign, John Nichol Spin qubits in quantum dots are a promising candidate for quantum information processing due to their long coherence and potential for scalability. However, hyperfine and charge noise in host semiconductor heterostructures make it challenging to achieve high-fidelity single- and two-qubit gates in these devices. Here, we report experimental work on implementing dynamically corrected gates in a Si/SiGe double quantum dot, which are designed to correct errors arising from hyperfine field fluctuations. We demonstrate dynamically corrected identity and Hadamard gates for a singlet-triplet qubit with high-fidelity. |
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G00.00270: Simulations of dynamically corrected gates in silicon singlet-triplet qubits Habitamu Y Walelign, Xinxin Cai, John Nichol Quantum information processing (QIP) requires extremely high-fidelity gates for its operation. Having long coherence times, spin qubits are promising candidates for QIP. However, charge and hyperfine noise in these systems limit gate fidelities. Dynamically corrected gates (DCG) can help reduce the errors due to these noise sources. Here we report simulations of identity and Hadamard DCGs to correct for hyperfine noise with high fidelity. |
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G00.00271: Mitigating electric and magnetic noise to enhance performance of a universal ion-based quantum computer Debopriyo Biswas, Liudmila Zhukas, Yichao Yu, Bahaa Harraz, Keqin Yan, Vivian Zhang, Crystal Noel, Alexander Kozhanov, Christopher Monroe Robust trapped ion quantum computers can be used to simulate numerous quantum phenomena and many-body physics systems, explore quantum error correction codes and noise models, and investigate challenges regarding scaling. Here, we present progress on building a state-of-the-art machine with full control of up to 32 171Yb+ ion qubits. We mitigate sources of electric field noise that affect the heating of motion and thereby our gate fidelity. We also built an enclosure for magnetic and acoustic shielding of the system. We discuss the electrical and magnetic field noise effect on the system performance leading to improved T2 time and lower heating rates. These performance upgrades should lead to better fidelity gates and expand the complexity of physics that we can simulate with our quantum processor. |
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G00.00272: Towards large scale quantum computing – a many qubit ion trap at room temperature Edgar Brucke, Philip Leindecker Large scale quantum computing is subject to extensive research and the ideal platform for general purpose quantum computers has yet to be found. Trapped ions as qubits excel in terms of gate fidelity and coherence times but so far systems have mostly been limited to only a small number of qubits. Our system is designed to support a linear chain of up to 50 ions which can be individually addressed, providing a versatile platform with many qubits and a high level of control. At the heart of the system is a 3-dimensional ion trap consisting of gold coated laser machined glass. The trap operates in ultra-high vacuum at room temperature. Individual addressing is implemented using a waveguide array. One application of this system is research towards large distance error correction, eventually enabling fault tolerant quantum computation. The high level of control is furthermore advantageous for the simulation of complex Hamiltonians, effectively performing quantum simulation at scale. Lastly, the segmented electrodes of the trap allow splitting of the ion chain into multiple segments for parallel quantum processing. |
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G00.00273: Exploring the viability of spin-transparent storage rings for quantum computing Matt Grau, Vasiliy S Morozov, Riad S Suleiman Charged particles in spin-transparent storage rings can exhibit long spin-coherence times of up to several hours, making them an interesting but untested prospect for quantum computing. Several of the critical requirements of quantum computing have been experimentally achieved: State-preparation is done by shining polarized light on a photocathode, emitting spin-polarized electrons. Single-qubit gates are performed by the arbitrary polarization rotations implemented by the pulsed magnetic field of a solenoid. Finally, readout of the spin-polarization state is done using a Mott-polarimeter. The remaining necessary ingredient for universal quantum computing is a way to perform two-qubit gates. While performing two-qubit operations on particles in the storage-ring appears challenging, we have identified a possible scheme to load electrons with entangled spins by generating them with an entangled train of light pulses on the photocathode. These spin-entangled electrons could then be used as a resource in a measurement-based scheme to perform multi-qubit gates in the storage ring. |
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G00.00274: Probing non-equilibrium steady-state phase transitions with trapped-ion quantum simulators Casey Haack, Daniel Paz, Mohammad F. Maghrebi, Zhexuan Gong Open quantum many-body systems with controllable dissipation can exhibit novel features in their dynamics and steady states. A paradigmatic example is the driven-dissipative transverse field Ising model (TFIM). It has been shown recently that the steady state of this model with all-to-all interactions is genuinely non-equilibrium near criticality, exhibiting a modified time-reversal symmetry violating the fluctuation-dissipation theorem. We demonstrate that such non-equilibrium behavior persists when the interactions are sufficiently long range, and this behavior can be observed in near-term ion trap quantum simulator experiments. In addition, we show that the driven-dissipative TFIM can be approximately simulated by a stroboscopic optical pumping process that is easier to achieve experimentally than continuous optical pumping. This stroboscopic protocol preserves the non-equilibrium signatures of the steady states, and can be employed to simulate correlated dissipation or prepare many-body entangled states in a robust way. |
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G00.00275: Towards large scale quantum computing – a many qubit ion trap at room temperature Philip Leindecker, Edgar Brucke Large scale quantum computing is subject to extensive research and the ideal platform for general purpose quantum computers has yet to be found. Trapped ions as qubits excel in terms of gate fidelity and coherence times but so far systems have mostly been limited to only a small number of qubits. Our system is designed to support a linear chain of up to 50 ions which can be individually addressed, providing a versatile platform with many qubits and a high level of control. At the heart of the system is a 3-dimensional ion trap consisting of gold coated laser machined glass. The trap operates in ultra-high vacuum at room temperature. Individual addressing is implemented using a waveguide array. One application of this system is research towards large distance error correction, eventually enabling fault tolerant quantum computation. The high level of control is furthermore advantageous for the simulation of complex Hamiltonians, effectively performing quantum simulation at scale. Lastly, the segmented electrodes of the trap allow splitting of the ion chain into multiple segments for parallel quantum processing. |
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G00.00276: High trap frequency achieved with miniature 3D printed ion trap Shuqi Xu, Xiaoxing Xia, Sumanta Khan, Qian Yu, Bingran You, Eli Megidish, Juergen Biener, Hartmut Haeffner Miniturized 3D printed trap is a good candidate for scalable quantum computing. The fabrication technology, two-photon polymerization direct laser writing, can print small, flexible and comlicated structures in micron scale, which allows one to combine the advantages of both macroscopic linear Paul traps and microscopic surface traps: high trap depth, high trap frequencies and scalability. Particularly, high trap frequencies speed up quantum operations and reduce the doppler cooled motional quanta to make state preparation faster. Here we present our work where we trapped Calcium 40 ions in a 3D printed Paul trap driven at 51.6 MHz, and achieved 24.15 MHz trap frequency, with stability parameter q of the Mathieu equation as high as 0.9. At around 20 MHz trap frequency, we are able to doppler cool the radial motional mode of trapped ions to a mean phonon number of 0.5, which could reduce the time needed for sideband cooling by an order of magnitude. |
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G00.00277: Quantum information processing with trapped electrons Qian Yu, Alberto M Alonso, Isabel Sacksteder, neha yadav, Hartmut Haeffner We explore electrons trapped in Paul traps as an attractive alternative to trapped ions to process quantum information. Quantum information can be encoded in the spin state of trapped electrons and their motional modes can be used as quantum bus to generate entanglement. |
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G00.00278: Description of fault tolerant quantum gate operations for topological qubit systems Adrian D Scheppe Among the list of major threats to quantum computation, quantum decoherence poses one of the largest because it generates losses to the environment within a computational system which cannot be recovered via error correction methods. These methods require the assumption that the environmental interaction forces the qubit state into some linear combination of qubit eigenstates. In reality, the environment causes the qubit to enter into a mixed state where the original is no longer recoverable. A promising solution to this problem bases the computational states on the low lying energy excitations within topological materials. The existence of these states is protected by a global parameter within the Hamiltonian which prevents the computational states from coupling locally and decohering. In this paper, the qubit is based on non-local, topological Majorana fermions (MF), and the gate operations are generated by swapping or braiding the positions of said MF. The algorithmic calculation for such gate operations is well known, but, the opposite gates-to-braid calculation is currently underdeveloped. Additionally, because one may choose from a number of different possible qubit definitions, the resultant gate operations from calculation to calculation appear different. Here, the calculations for the two- and four-MF cases are recapitulated for the sake of logical flow. This set of gates serves as the foundation for the understanding and construction of the six-MF case. Using these, a full characterization of the system is made by completely generalizing the list of gates and transformations between possible qubit definitions. A complete description of this system is desirable and will hopefully serve future iterations of topological qubits. |
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G00.00279: Hybrid Superconducting Circuit Devices for Sensing Quantum Materials Sheng-Wen Huang, Ramya Suresh, Botao Du, Peter Salisbury, Jian Liao, Leonid P Rokhinson, Yong P. Chen, Ruichao Ma To study quantum materials and topological excitations, superconducting quantum circuits are natural platforms capitalizing the precise probe and control of microwaves with the tools of circuit quantum electrodynamics (cQED). In addition, hybrid superconducting circuit devices could have gate tunability and noise protection from the novel properties of topological materials. A transmon-like qubit with superconductor-topological insulator-superconductor (S-TI-S) junction has been designed, fabricated, and incorporated into a 3D copper cavity. Coherent transport properties of the TI material at the single quantum level could be revealed by the spectroscopic and time-domain measurements of the 3D TI-transmon qubit. We will also discuss other efforts to develop superconducting circuits and qubit-based sensors for probing quantum materials, materials defects, and other excitations. |
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G00.00280: New experimental platform for two-dimensional helium film adsorbed on a graphene substrate Yongmin Kang, Junho Lee, Eunseong Kim Graphite substrate has been widely utilized to investigate the exotic properties in two-dimensional adsorbed films. Especially, adsorbed 4He film on graphite exhibits various interesting nonclassical phases such as a registered solid phase and a superfluid phase. However, the intriguing quantum behaviors have not been clarified due to the lack of sensitivity by the unwanted tortuosity in conventional graphite substrates. Here, we propose a cavity optomechanical system as a new experimental platform to resolve the properties of the helium on graphite. The mass and stiffness change on the helium film can be directly reflected on responses of the graphene mechanical resonator. The mechanical motion of a graphene resonator can be monitored through a capicively coupled superconducting coplanar waveguide cavity using optomechanically induced transparency. We present the progress in the fabrication of the on-chip cavity optomechanical system. This highly sensitive measurement scheme can be utilized as an ultimate platform to study the 2D nature of quantum and classical gases. |
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G00.00281: Path to scaleup technologies for cryogenic quantum computing platforms Yaniv Kurman, Yonatan Cohen, Lior Ella Scaling up the number of qubits in quantum computers is essential for reaching useful quantum computing. One fundamental limitation on the number of qubits in cryogenic platforms, such as superconducting circuits and semiconductor quantum dots, is due the heat load capacity of dilution fridges and the power consumption per qubit. It was shown recently by Wallraff et al. [1] that engineering commercial cryogenic setups in terms of attenuator distributions and cabling choice can enable the support of 100 qubits. In this proposal, we present a system-level end-to-end analysis of the different technological avenues towards the scaling of commercially available cryogenic platforms for quantum computers. We overview and compare the requirements and limitations of current state of the art systems and analyze the next generation development in the field of cryogenic cabling and electronics. In such systems, we expect at least doubling the qubit capacity of commercial dilution fridges in the near future. |
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G00.00282: The Kerr-cat qubit: towards enhanced error suppression using dissipation Sergey Hazanov, Daniel Chausovsky, Lalit Joshi, Fabien Lafont, Serge Rosenblum Biased-noise qubits are a promising approach for realizing hardware-efficient quantum processors. By sufficiently suppressing the bit-flip error rate, the complexity of error correction schemes can be relaxed to a repetition code in the limit of infinite noise bias. One prominent candidate for this architecture is the Kerr-cat qubit, implemented by squeezing a Kerr-nonlinear oscillator. The Kerr-cat qubit admits superpositions of the oscillator's coherent states, i.e., cat states, as degenerate ground states. Under the cat-state encoding, the rate of bit-flip errors decreases exponentially with the amplitude of the coherent states. However, recent work has shown that leakage outside the computational manifold limits the suppression of bit-flip errors below the exponential limit [1]. Theoretical work has shown that such leakage can be mended by introducing carefully designed dissipative interactions [2, 3]. Here we show progress toward incorporating engineered dissipation mechanisms to enhance the qubit's bit flip time. |
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G00.00283: Scalable fabrication of Hemispherical Solid Immersion Lenses in Silicon Carbide by Greyscale Lithography Cristian Bonato, Christiaan Bekker Microscale solid immersion lenses (SILs) can enable efficient extraction of single photons from single solid-state quantum emitters. In solid-state matrices, photon collection is limited by total internal reflection, which traps most of the emission into the high-index medium. By removing refraction at large angles, SILs can boost collection efficiency by a factor 10-20, as shown for example for the spin/photon interface associated with single nitrogen-vacancy (NV) centers in diamond. SILs are typically fabricated by Focused Ion Beam, a process which is inherently non-scalable, slow and expensive. |
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G00.00284: Characterization of the nuclear spin environment in 4H-silicon carbide for single shot readout Erik Hesselmeier, Pierre Kuna, Vadim Vorobyov, Majid Zahedian, Tobias Linkewitz, Timo Steidl, Di Liu, Viktor Ivady, Wolfgang Knolle, Tien Son Nguyen, Jawad Ul-Hassan, Florian Kaiser, Jörg Wrachtrup The V2 center in silicon carbide emerged as platform for CMOS compatible optically interfaced spin systems in the solid state. Recently, long coherence times and nearly transform limited photon emission were shown, even after integration into nanostructures. Furthermore, two weakly coupled nuclear spins were coherently controlled [1]. However, the V2 center inherits a strong phonon coupling to a metastable state manifold, leading to electron spin flip processes. This currently limits the readout fidelity. Our goal is to overcome this issue by implementation of a nuclear spin assisted single shot readout scheme [2]. |
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G00.00285: A membrane platform for enhancing the emission of color centers in 4H-SiC with photonic resonators Jonathan Körber, Jonah Heiler, Erik Hesselmeier, Marcel Krumrein, Rainer Stöhr, Philipp Fuchs, Jannis Hessenauer, Christoph Becher, David Hunger, Jawad Ul-Hassan, Georgy V Astakhov, Florian Kaiser, Jörg Wrachtrup 4H-silicon carbide (SiC) has recently emerged as a promising platform to host point defects with possible applications in quantum technologies, such as distributed quantum computing or sensing. Single silicon-vacancy centers in 4H-SiC have already shown to comprise desirable properties in this regard, such as nearly-lifetime-limited optical linewidths, photon indistinguishability and spin coherence times on the order of ms at low temperatures [1,2]. However, light emitted from such color centers typically is collected very inefficiently when using confocal microscopes and unstructured samples (< 1% collection efficiency) due to the high refractive index of the material. Additionally, silicon-vacancy centers in 4H-SiC show only a small fraction of emission into the zero-phonon line (~8-9%) [3]. To overcome these limitations, we make use of a platform based on (sub-)µm-thin membranes in 4H-SiC, created by lapping, chemical-mechanical polishing and reactive-ion-etching of bulk material, with two different approaches: Firstly, we directly fabricate photonic resonators from sub-µm-thin membranes and secondly, we want to integrate µm-thin membranes into open-access Fabry-Pérot cavities. Here, we report on recent updates of our work including the fabrication of membranes with integrated color centers and a characterization of their optical properties for different membrane thickness. |
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G00.00286: Multicore quantum computing Hamza Jnane, Brennan Undseth, Balint Koczor, Zhenyu Cai, Simon C Benjamin Any architecture for practical quantum computing must be scalable. An attractive approach is to create multiple cores, computing regions of fixed size that are well-spaced but interlinked with communication channels. This exploded architecture can relax the demands associated with a single monolithic device: the complexity of control, cooling and power infrastructure as well as the difficulties of cross-talk suppression and near-perfect component yield. Here we explore interlinked multicore architectures through analytic and numerical modelling. While elements of our analysis are relevant to diverse platforms, our focus is on semiconductor electron spin systems in which numerous cores may exist on a single chip within a single fridge. We model shuttling and microwave-based interlinks and estimate the achievable fidelities, finding values that are encouraging but markedly inferior to intra-core operations. We therefore introduce optimised entanglement purification to enable high-fidelity communication, finding that 99.5% is a very realistic goal. We then assess the prospects for quantum advantage using such devices in the NISQ-era and beyond: we simulate recently proposed exponentially-powerful error mitigation schemes in the multicore environment and conclude that these techniques impressively suppress imperfections in both the inter- and intra-core operations. |
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G00.00287: Implementing Lattice Gauge Theories on Quantum Computers Julius Mildenberger, Wojtek Mruczkiewicz, Jad Halimeh, Zhang Jiang, Philipp Hauke Digital quantum simulators provide a table-top platform for addressing salient questions in particle and condensed-matter physics. A particularly rewarding target is given by lattice gauge theories (LGTs). Their constituents, e.g., charged matter and the electric gauge field, are governed by local gauge constraints, which are highly challenging to engineer and which lead to intriguing yet not fully understood features. |
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G00.00288: Brain-Box Quantum Autoencoder for entangled state production Joséphine Pazem, Mohammad H Ansari The Quantum Autoencoder (QAE) is a quantum neural network. In presence of harmful noise channels, the QAE can be trained to generate high-fidelity Greenberger-Horne-Zeilinger states. We identify a few failure mechanisms in the process and we show a large improvement in the noise tolerance by using a multi-qubit structure called "brain box" (BB). |
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G00.00289: Re-uploading classical data points using Quantum M-P Neural Network Safura Sharifi, Sara Aminpour The computational capabilities of a single qubit can be used to construct a universal quantum classifier when combined with a classical subroutine. Although a single qubit provides only a simple superposition of two states, and single-qubit gates only rotate in the Bloch sphere, the key is to allow multiple data re-uploads to circumvent these limitations. By re-uploading data and processing every single qubit, a quantum circuit can be constructed. Furthermore, both data re-uploading and measurements can accommodate a multidimensional input and multiple categories in the output. As a result of analyzing conventional M-P neural networks using quantum linear superpositions, this paper presents a quantum M-P neural network with data re-uploading. We use a weight-updating algorithm for a universal quantum classifier and compare it with Data re-uploading for a universal quantum classifier. |
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G00.00290: Temporal quantum tomography with weak measurements Atithi Acharya, Cesar Lemma, Vadim Oganesyan, Anirvan M Sengupta Quantum tomography consists of the characterization of quantum states and processes from experimental measurements. If no prior knowledge of the state exists, tomography requires measurements from multiple samples. However, tomography for a quantum system with temporal processing is a fundamentally different problem. The problem is ill-posed and information about the state is lost due to the decoherence. We can still learn the properties of our input state and the dynamics under the appropriate setting. We use weak measurement history to predict the initial state of the measured quantum system. Unlike projective measurements, weak measurements make small stochastic changes to the system while giving a signal about the quantum state allowing for continuous monitoring. We also learn the dynamics of the system by learning the Kraus operators corresponding to the dynamics. By doing both, we lay out the procedure to separate the non-trivial dynamics from that caused by measurements, thus working towards quantum systems identification, and ultimately, towards adaptive quantum control. |
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G00.00291: Simulating quantum error mitigation in fermionic encodings Riley Chien, Kanav Setia, Xavier Bonet-Monroig, James D Whitfield, Mark Steudtner The most scalable proposed methods of simulating lattice fermions on noisy quantum computers employ encodings that eliminate nonlocal operators using a constant factor more qubits and a nontrivial stabilizer group. In this work, we investigated the most straightforward error mitigation strategy using the stabilizer group, stabilizer postselection, that is very natural to the setting of fermionic quantum simulation. We numerically investigate the performance of the error mitigation strategy on a range of systems containing up to 42 qubits and on a number of fundamental quantum simulation tasks including non-equilibrium dynamics and variational ground state calculations. We find that at reasonable noise rates and system sizes, the fidelity of computations can be increased significantly beyond what can be achieved with the standard Jordan-Wigner transformation at the cost of increasing the number of shots by less than a factor of 10, potentially providing a meaningful boost to near-term quantum simulations. Our simulations are enabled by new classical simulation algorithms that scale with the logical Hilbert space dimension rather than the physical Hilbert space dimension. |
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G00.00292: Reference-State Error Mitigation: A Strategy for High Accuracy Quantum Computation of Chemistry Werner Dobrautz, Phalgun Lolur, Mårten Skogh, Christopher W Warren, Janka Biznárová, Amr Osman, Giovanna Tancredi, Goran Wendin, Jonas Bylander, Martin Rahm Decoherence and gate errors severely limit the capabilities of state-of-the-art quantum computers. This work introduces a strategy for reference-state error mitigation (REM) of quantum chemistry that can be straightforwardly implemented on current and near-term devices. REM can be applied alongside existing mitigation procedures, while requiring minimal post-processing and only one or no additional measurements. The approach is agnostic to the underlying quantum mechanical ansatz and is designed for the variational quantum eigensolver. Up to two orders-of-magnitude improvement in the computational accuracy of ground state energies of small molecules (H2, HeH+ and LiH) is demonstrated on superconducting quantum hardware. Simulations of noisy circuits with a depth exceeding 1000 two-qubit gates are used to demonstrate the scalability of the method. |
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G00.00293: Discrete Time Quantum Walk (DTQW) implemented in superconducting cavity QED architectures. Jiwon Kang, Eunseong Kim Quantum walk (QW) has been implemented in various quantum mechanical systems such as superconducting qubit, photonic, and Rydberg atom systems and attracted considerable attentions due to its promising applications to quantum simulations and quantum algorithms. Here, we propose an idea to possibly resolve some issues in 1D discrete-time-quantum-walk(DTQW) experiment in superconducting qubit system. Our DTQW can utilize a consecutive dynamic protocol operated in two separate cylindrical stub readout and storage cavities that are intercoupled via a transmon qubit, which may allow us to avoid the existing limitations in DTQW imposed by the non-orthogonality of storage cavity's coherent states. Accordingly, QW can be realized in the Fock space, not QW in phase space, by utilizing high Q-factor cylindrical stub cavity structure. In addition, it is expected that this new approach could achieve a multi-dimensional DTQW. |
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G00.00294: Auxiliary Microwave Circuit for Broadband Josephson Parametric Amplifier for Multiplexing Qubit Readout Taegun Joo, Eunseong Kim We introduce an auxiliary microwave circuit which expands the bandwidth of a Josephson parametric amplifier(JPA) by transforming its coupling impedance to the environment. A conventional JPA shows a few tens of MHz bandwidth that is not sufficient to perform multi-qubit controls. Previous study reported the broadening of the bandwidth by coupling a JPA strongly with the environment thorough an impedance reducing circuit that lowers its loaded quality factor.[1] Besides, the introduction of frequency dependent coupling impedance, which behaves as an LC resonator, expands the bandwidth further.[2] Here we optimized the parameters in various types of impedance transforming circuits designed to obtain the stable performance with extended bandwidth. We will test and verify various types of the auxiliary circuits experimentally for the most desirable performance of a broadband JPA. |
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G00.00295: Three-wave mixing in travelling-wave parametric amplifiers Hampus R Renberg Nilsson, Anita Fadavi Roudsari, Daryoush Shiri, Per Delsing, Vitaly Shumeiko We develop a theory for a Josephson junction based travelling-wave parametric amplifier (TWPA) operating in the three-wave mixing regime and propose a scheme for achieving a high gain [1]. We take into account the discreteness of the Josephson junction chain to fully characterise a negative effect of spectral dispersion at high frequencies close to the cutoff. We also analyse the gain suppression by the high harmonic generation at the small frequency part of the spectrum. To achieve a high gain, we propose to engineer a chain with a spectral gap and to place the pump frequency above the gap close to the spectral cutoff. We find that there exists a sweet spot for the pump, where the signal injected below the gap and the pump are phase matched, while up-conversion is inhibited. Under these conditions an efficient amplification, above 20 dB, occurs within a bandwidth in the GHz range. |
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G00.00296: Psitrum and Simulation of Decoherence in Quantum Algorithms Mohammed Alghadeer, raja selvarajan, Sabre Kais, Fahhad H Alharbi Quantum computation is a radical new candidate for a technology that is capable to make a paradigm shift in information processing. However, current promising devices are limited in performance due to many decoherence mechanisms. Quantum computer simulators are thus important for understanding and solving existing problems of the current noisy intermediate-scale quantum (NISQ) processors. In this work, we present Psitrum – a universal gate-model based quantum computer simulator implemented on classical hardware. The simulator allows to emulate and debug quantum algorithms in form of quantum circuits for many applications with the choice of adding quantum noise that limit coherence of quantum circuits. We will show how to use visualization tools available in the software to demonstrate the simulation of quantum circuits for various quantum algorithms. In addition, we will present the factorization problem using standard Variational quantum eigensolver (VQE) on Psitrum and present the results of several circuits to factorize prime numbers and show the effect of decoherence on the solution probability and training of cost function. This is when decoherence is modeled by deleterious effects of depolarizing channels imposed on quantum gates. This also demonstrates that, Psitrum provides features for simulating noisy and noiseless quantum circuits to solve a wide class of quantum algorithms available for current NISQ processors. In future, by adding more features, Psitrum will help to provide a good starting point to newcomers for a good experience with our visual learning tools. Psitrum software and source codes are freely available at: https://github.com/MoGhadeer/Psitrum. |
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G00.00297: QContext: Context-Aware Decomposition for Quantum Gates Ji Liu, Max Bowman, Pranav Gokhale, Siddharth Dangwal, Jeffrey Larson, Frederic T Chong, Paul Hovland We propose QContext, a new compiler structure that incorporates context-aware and topology-aware decompositions. The standard compilers typically use the same decomposition template when decomposing the same gates. Because of circuit equivalence rules and resynthesis, variants of a gate-decomposition template may exist. QContext exploits the circuit information and the hardware topology to select the gate variant that increases circuit optimization opportunities. QContext is aware of both the gate context and the target hardware topology. We study the basis-gate-level context-aware decomposition for Toffoli gates and the native-gate-level context-aware decomposition for CNOT gates. We also propose new templates for the Toffoli and CNOT gates. Our experiments on a benchmark set of problems show that QContext reduces the number of two-qubit gates and single-qubit gates as compared with the state-of-the-art approach. |
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G00.00298: Teleportation-based Synthesis for Quantum Computers Henry C Zou Hardware constraints in modern quantum architecture pose a major obstacle to large-scale quantum computing. Due to the restrictions of qubit connectivity, most quantum algorithms cannot be directly performed on current quantum systems. To execute the two-qubit gates in these algorithms, additional logic must be inserted to move the qubits being acted next to each other. Traditional protocols for solving the quantum routing problem use SWAP gates, which swap the states of any two connected qubits. Ideally, the routing solution aims to minimize the number of gates or the depth of gates, but finding an optimal solution is an NP-hard task. |
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G00.00299: On Extending Capabilities of Quantum Error Correcting Codes to Handle Amplitude Damping Errors Al-Maliq O Adetunji, Pradip Bhattarai, Kishor T Kapale Qubits, the building blocks of quantum computers, hold quantum states that store information. Through the operations of quantum gates, information embedded in the qubits can be manipulated. Unfortunately, the microscopic nature of qubits makes them susceptible to noise, and the gate operations they are subjected to can be erroneous themselves. These factors diminish the possibility of accurate calculations on actual quantum hardware; nevertheless, fault-tolerant quantum computing has been mathematically demonstrated. Fault-tolerant quantum computers employ qubit-controlling protocols with underlying quantum error-correcting codes (QEC) to consistently correct errors that arise due to the aforementioned factors. Predominantly, fault-tolerant protocols have been developed around QEC codes that correct a popular range of errors, namely, Pauli-errors. However, the performance of these codes is impaired by their limited capabilities in correcting various other types of errors, such as the amplitude-damping error. In this work, we investigate development of a framework to incorporate amplitude-damping error correction into the standard QEC codes. With this framework, we seek a higher accuracy fault-tolerance scheme against not only Pauli-based errors but amplitude-damping errors. |
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G00.00300: Machine learning for Hamiltonian tomography of photosynthetic excitation energy transfer complexes Kimara Naicker Classical machine learning (ML) models are used to study the quantum dynamics of excitation energy transfer (EET) within light harvesting complexes (LHCs). The numerically exact method used to simulate the dynamics is the hierarchical of equations of motion (HEOM) [2-4]. |
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G00.00301: Quantum Computation for Simulating Periodic Solid-state Systems Using Plane-wave Basis Qian Wang, Alice Hu Schrödinger equation is a notorious high dimensional partial differential equation. The “curse of dimensionality” makes Schrödinger equation very difficult to be solved accurately. As quantum computer has inherent advantage on solving quantum many-body system without wavefunction sign problem, quantum strategies are considered as the future promising ways to solve high dimensional Schrödinger equation. Here, we firstly adopt the Kohn-Sham wavefunction with the plane-wave basis sets and sophisticated pseudopotentials, which permit us to efficiently and accurately construct the Hamiltonian for solid-state materials. Secondly, we develop an enhanced qubit-efficient encoding scheme for reducing the qubit number to satisfy N reference states of specific conditions and symmetries. Then, we utilize an imaginary-time control for less resource requirements and error mitigation. Finally, we numerically demonstrate that this method for ground-state preparation and energy estimation requires Ο(log2N) qubits in total, and successfully predicts electronic band structure properties of several systems such as hydrogen chain and multi-component solid-state materials. Our quantum algorithm and results show the feasibility of quantum simulations for large-scale quantum systems in the current noisy intermediate-scale quantum (NISQ) device. |
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G00.00302: Adaptive ground state preparation through randomization Prakriti Biswas, Christian Arenz Variational quantum algorithms (VQAs) operate by using classical and quantum computing resources in tandem to solve, in an iterative loop, an optimization problem. However, several challenges associated with ansatz selection, rugged optimization landscapes, and noise exist. Rather than fixing a parameterized quantum circuit as an ansatz to solve the optimization problem, adaptive quantum algorithms aim to overcome these issues by adaptively creating the quantum circuit that minimizes the objective function. However, since the optimization problem is typically non-convex, similar to traditional VQAs, adaptive strategies can get stuck in sub-optimal solutions. |
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G00.00303: Representation of stochastic nonlinear dynamical systems with open bosonic quantum systems Alexander Engel, Graeme Smith, Scott E Parker One approach for approximating nonlinear dynamics on quantum computers is to express the target dynamical system as a mean-field theory for a quantum system of many identical particles which can be simulated efficiently with quantum algorithms. However, rigorous analyses indicate that maintaining accuracy of bosonic mean-field systems out to long times t requires a number of bosons n that is exponentially large in t. Therefore, that approach does not appear to allow for a quantum speedup of nonlinear dynamics beyond short simulation times. Instead, we generalize this idea to open bosonic quantum systems, and find that there is an exact mapping to stochastic nonlinear dynamical systems. The stochastic terms give finite-n corrections to the mean-field theory evolution. We demonstrate this mapping through numerical testing of simple systems. If the target dynamics is actually given by a stochastic dynamical system, or if weak stochastic terms are acceptable as errors to the target dynamics, then a fixed number of bosons n can be considered for arbitrary t. This may allow for a quantum speedup based on quantum simulation of the open bosonic system. |
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G00.00304: Two Quantum Algorithms accelerating traditional Machine Learning Boning Li, Hao Tang, Guoqing Wang, Haowei Xu, Changhao Li, Ariel R Barr, Paola Cappellaro, Ju Li With growing demands of complex models that requires increasing amount of training data and larger parameter space, the efficiency of traditional machine learning is limited by its communication and computational complexity. Here we present a communication-efficient quantum algorithm that tackles two traditional machine learning problems, the least-square fitting and SoftMax regression problem, in the scenario where the data set is distributed across two parties. Our quantum algorithm finds the model parameters by solving linear equations with a communication complexity of $O(frac{log_2(N)}{epsilon})$, where $N$ is the number of data points and $epsilon$ is the bound on fitting parameter errors. Compared to classical algorithms and other quantum algorithms that achieve the same task, our algorithm provides a communication advantage in the scaling with the data volume. Further, we show that the building block of our algorithm, the quantum-accelerated estimation of inner product and Hamming distance, has time complexity of $O(frac{log_2(N)}{epsilon})$. Using similar building block we also provide[BL2] an algorithm that accelerate the parameter optimization process of non-linear problems with time complexity $O(frac{log_2(N) log_2(N')}{epsilon^{3/2}})$, where $N$ is the size of parameter space. |
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G00.00305: Simulations of dissipative electromagnetic waves using quantum singular value transformation Ivan Novikau, Ilya Y Dodin, Edward A Startsev Quantum Singular Value Transformation (QSVT) is a state-of-the-art quantum algorithm for solving linear vector equations of the form Ax = b, including those with non-Hermitian matrices A. We report an application of the QSVT to the modeling of classical electromagnetic waves in a one-dimensional system with outgoing boundary conditions. We show how to encode the corresponding non-Hermitian boundary-value problem into a quantum circuit and also propose how to extract classical information from this circuit using quantum measurements. In particular, we show how the absorption power can be measured using an oracle emulating the electric conductivity. The potential speedup and the drawbacks of QSVT applications to classical waves are also discussed. |
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G00.00306: Global Optimization with the Iterative Power Algorithm via Quantum Computing and Quantics Tensor Trains Micheline B Soley, Thi Ha Kyaw, Paul Bergold, Brandon Allen, Chong Sun, Alán Aspuru-Guzik, Victor S Batista Although global optimization is essential to many disciplines of science, from quantum control to machine learning, today's global optimization algorithms frequently become mired in local minima traps. We present the iterative power algorithm (IPA) and prove the method circumvents local minimum traps to converge to global minima. In IPA, the function to be optimized is represented as a potential energy surface (PES). A density is placed in the PES and acted on by an oracle that localizes the density at the global minimum locations. We demonstrate the quantics tensor-train implementation of IPA successfully identifies global minima in model potential energy surfaces with up to 250 local minima. We also show the method can be employed on quantum computers via the McLachlan variational principle. The resulting method is found to outperform one of the foremost quantum computing approaches for H2 ground state optimization, quantum processor design, and prime factorization. |
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G00.00307: An efficient framework for implementing the factorized unitary coupled-cluster ansatz circuit for quantum chemistry on a quantum computer using the linear combination of unitaries Luogen Xu The factorized form of the UCC ansatz can be systematically applied to a single-reference state to generate a variational wavefunction for a molecule that is accurate to chemical accuracy. The cost of the ansatz circuit comes mainly from the number of multi-qubit entanglement gates, which grows rapidly with the number of active spin orbitals. In this work, we propose a new framework for implementing the factorized UCC ansatz by directly simulating its alternative form derived from an exact Euler-like SU(2) operator identity for each UCC factor. We include a detailed method for preparing the ancilla bank, as well as a circuit for the select(U) operator for factorized UCC doubles. We then prove that the scheme works for factorized UCC operators of any rank. This result has the potential to prepare the factorized UCC ansatz on near-term hardware with significantly reduced circuit depth. |
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G00.00308: Wireless packet scheduling with Quantum Computing Yungjun Yoo, Richard Jaepyeong Cha We present the quantum formulation of wireless packet scheduling algorithm to support QoS (quality of services) in fading channel. We show that existing scheduling algorithm with classical computer can be extended to support the quantum device as well. With support of quantum search algorithm (Grover’s algorithm), we expect to reduce great amount of calculation time for wireless packet scheduling algorithm by factor of square root. We show that how Quantum search algorithm can be used to implement the wireless packet scheduler. In addition, we investigate the possible applicable schemes and benefits of the quantum formulated wireless packet scheduling algorithm for different systems (broadcast, unicast, and multicast) and propose the model which could be beneficial to support the future wireless network. |
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G00.00309: Performance of quantum network applications utilising multiple contemporaneous quantum resources Bethany Davies, Gayane Vardoyan, Stephanie Wehner We study the performance of contemporaneous quantum resource establishment between two distant nodes which are components of a near-term quantum network, enabling the two parties to attempt bipartite entanglement generation in a sequential manner. Each resource is created using the successfully generated entangled pairs and is subject to a lifetime limit, known as a cut-off, which triggers resource expiration -- possibly on both sides of the link -- causing a reset of the corresponding qubits. To carry out the execution of certain distributed quantum applications, the parties must be able to generate all quantum resources within the time window specified by this cut-off on qubit storage. For both a finite and infinite window cut-off, we utilise methodology from sequential window problems and scan statistics literature to obtain solutions for the first and second moments of the waiting time. We then go further to obtain the fidelity distribution of the resulting quantum states, which encapsulates information about their ages. As an application of these results, we demonstrate how they can be used to study sufficient parameter regimes for carrying out Verifiable Blind Quantum Computation in the presence of imperfect entangled links and memory decoherence. We present a method that, in the presence of an arbitrary function capturing the trade-off between the rate and fidelity of an entangled link, finds the optimal choice for the window size which minimises the expected time taken to carry out one component round of the protocol. In this way, we connect parameters corresponding to the underlying network architecture to the performance of the VBQC application. |
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G00.00310: Resource sharing in a multi-user quantum network George Iskander, Joaquin F Chung Miranda, Rajkumar Kettimuthu, Xu Han As fiber-based quantum communication experiments evolve from table top demonstrations within a lab to demonstrations over local area and metropolitan area networks, technologies are being developed to realize a practical quantum network. An important aspect of practical quantum networks is to enable multiple users to request and consume quantum resources simultaneously and even share the infrastructure with classical signals. In this talk, we will present our research on resource sharing approaches to accommodate multiple users in a quantum network. One such approach is to interleave user access to the network in which the user requests are interleaved in a short enough timespan such that the requests do not incur noticeable delays as opposed to a sequential approach in which if two (almost simultaneously arriving) requests need time t on the network, then one must wait time t to start. We will present the results of our study that includes the above-mentioned (and possibly other) approach(es) on a simple local-area quantum network with a three-channel entangled photon source, two SNSPDs, and a four-channel time tagger. |
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G00.00311: Quantum Edge Computing William J Munro, Nicolo Lo Piparo, Kae Nemoto It is well-known that a future quantum internet will be able to distribute and process quantum information on the planetary scale – whether this is for quantum communication, distributed computation or even remote quantum metrology like tasks. Such an internet will in the long term be formed from quantum error corrected links able to distribute information over large distances all while maintaining their coherence for long periods of time. The key question however is how we evolve from today small-scale test networks to that future quantum internet. How do we bridge this divide? Quantum edge computing which involves the user data being processed as close as possible to the source as possible at the periphery of the network is one potential solution. This is quite different from the inherently centralized quantum cloud computing approach. |
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G00.00312: SEAQUE (Satellite Entanglement and Annealing Quantum Experiment) Kelsey Ortiz Establishing quantum light systems in space is an essential step towards building a quantum network that would provide benefits such as connecting quantum nodes, providing secure communication, and improving distributed sensing. However, there are no American led initiatives for a quantum satellite to date. SEAQUE (Satellite Entanglement and Annealing QUantum Experiment) hopes to serve as the first American quantum satellite in orbit by utilizing the Nanoracks Bishop Airlock on the International Space Station. The source will use integrated optics, as opposed to a bulkier crystal system, to generate polarization-entangled photons. Bell inequalities and tomography’s will be measured to characterize the quality of entanglement while in orbit. The current flight source has a Bell inequality violation of 2.758 ± 0.006 along with a purity and fidelity of 0.984 ± 0.002 . Additionally, SEAQUE will combat radiation damage that occurs on single photon detectors in space through laser annealing. Whereas other quantum satellites will degrade over time, we hope to show that the self-healing quality of SEAQUE will extend its lifetime for over a year. |
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G00.00313: Side-Channel-Free Quantum Key Distribution Source using a KTP Polarization Modulator and a Broadband Laser TAHEREH REZAEI, Andrew Conrad, Daniel J Gauthier, Paul G Kwiat We discuss progress toward demonstrating a side-channel-free decoy-state quantum key distribution (QKD) source based on a polarization-modulator and a wavelength-stable attenuated pulsed laser. By modulating the polarization of the quantum state, a QKD encoding with three states is attained. The polarization-modulator-based QKD source enhances security by eliminating side-channel attacks based on spectral, spatial, or temporal distinguishability when multiple sources are used to generate the different QKD states. Herein, we describe our QKD source design and evaluate critical subsystems metrics, including the quantum bit error rate (QBER), quantum state tomography, and achievable key rates. The QKD source is designed to function with minimum size, weight, and power (SWaP). In our system, we use a commercial KTP waveguide modulator (AdvR, Inc.). Our QKD source operates with both narrow-band and broad-band lasers, and we show characterization results using a He-Ne laser and a diode laser, respectively. The polarization-modulator-based QKD source has potential in future mobile quantum networks, such as unmanned aerial vehicles (UAV) and autonomous vehicles, in addition to fixed fiber-based quantum networks. |
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G00.00314: Fluorescent Nanodiamonds for Light-Controlled Intracellular Heating and Nanoscale Temperature Sensing Priyadharshini Balasubramanian Subcellular thermometry is a promising tool for elucidating the role of temperature in biological processes. Especially, temperature-induced cell death has gained attention as a potential therapy for cancer where photothermal agents are utilized as subcellular heat generators to initiate cell death. To improve the efficacy of photothermal therapy (PTT), knowledge of the local temperature change that induces apoptosis is crucial. Hence, measuring such subcellular temperature change with high precision is of critical importance for diagnostics, therapeutics, and disease prognosis. |
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G00.00315: Entanglement-assisted detection of fading targets via correlation-to-coherence conversion Xin Chen, Quntao Zhuang Quantum illumination (QI) utilizes an entanglement-enhanced sensing system to outperform classical illumination (CI) in detecting a suspected target, despite the entanglement-breaking high loss and noise environment. In the ideal scenario when the target has known reflectivity and fixed return phase, the Gaussian nature of the channel allows the design of receivers and exact evaluation of their performance advantages, such as optical parametric amplifier receiver. In practical applications, however, targets have Rayleigh-distributed reflectivities and random return phases; such receivers become useless and more complex receivers preclude exact evaluation of the quantum advantages, due to the non-Gaussian nature of the channel and receiver [Phys. Rev. A 96, 020302 (2017)]. The correlation-to-coherence (‘C->D’) conversion module is a recently proposed receiver paradigm which has a wide application such as target detection, phase estimation, and classical communication. In this paper, we show the performance advantage over CI is maintained albeit |
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G00.00316: Fundamental limits to quantum metrology with noncommuting generators James Gardner, Tuvia Gefen, Yanbei Chen Precision metrology across many applications, e.g. gravitational-wave detection, has reached or is fast approaching the quantum limit. In the quantum regime, the fundamental limit on parameter estimation is set by the information-theoretic Quantum Cramer-Rao Bound, e.g. the Energetic Quantum Limit/Mizuno Theorem for gravitational-wave interferometers. Although this limit can be saturated in single-variable cases, for multiple and continuous parameter estimation it is missed by up to a factor of a square-root of two in the signal-to-noise ratio if the probe observables (the generators of the unitary transformation) do not commute. This is the case for detuned gravitational-wave interferometers where the amplitude quadrature of the intra-cavity light does not auto-commute at different times. In this work, we explore how the missing factor can be restored and the sensitivity improved. We also consider the effects of losses. |
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G00.00317: First-principles Calculation of the Temperature-dependent Transition Energies in Spin Defects Hao Tang, Ariel R Barr, Guoqing Wang, Paola Cappellaro, Ju Li Spin qubits associated with color centers are promising platforms for various quantum technologies. However, to be deployed in robust quantum devices, the variations of their intrinsic properties with the external conditions, and in particular, temperature, should be known with high precision. Unfortunately, a predictive theory on the temperature dependence of the resonance frequency of electron and nuclear spin defects in solids remains lacking. In this work, we develop a first-principles method for the temperature dependence of zero-field splitting, hyperfine interaction, and nuclear quadrupole interaction of color centers. As a testbed, we compare our ab-initio calculation results with experiments in the Nitrogen-Vacancy (NV) center finding good agreement. Interestingly, we identify the major origin of temperature dependence as a second-order effect of phonon vibration. Applying our method to various color centers, we provide theoretical predictions of the temperature effects on solid spin qubits for designing high-precision quantum sensors. |
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G00.00318: Theoretical Information Limits for a Quantum Entangled Network of Magnetometers Lindsey Tensen, Julian Martinez-Rincon Distributed quantum sensing is expected to offer innovative paths to accelerate the development of time synchronization [1], sensing capabilities of gravity gradients and magnetic fields [2], and to advance the search of new physics, such as dark matter domain walls [3]. Classical networks vary widely in structure depending on their randomness, modularity, and heterogeneity. We study a tree network, where each node represents an individual magnetometer. The Fisher Information is then used to determine the maximum amount of information we can recover about one parameter from the measurements. For an electromagnetically induced transparency (EIT) magnetometer, we are interested in how small of a phase shift can be detected within a global homogeneous magnetic field. We then use the Cramer-Rao bound to determine the lowest limit in uncertainty of our measurements. We iterate this process for one single magnetometer, then a classical network followed by an entangled network. By comparing our results for both a classical and quantum network, entangled nodes are able to improve the uncertainty of our measurements by a factor scaling up to the square root of the number of nodes. By improving measurement sensitivity for a network of magnetometers, we aim to be able to detect increasingly small shifts in a magnetic field. The improvements gained by entangling a network have widespread applications, from quantum sensing to the search for exotic physics in the HEP community. |
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G00.00319: Characterizing the Interaction Graph of a Multi-Spin Network in Diamond Alex Ungar, Won Kyu Calvin Sun, Alexandre Cooper-Roy, Paola Cappellaro
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G00.00320: Sensing arbitrary frequency fields using a quantum mixer Guoqing Wang, Yi-Xiang Liu, Jennifer M Schloss, Scott T Alsid, Danielle A Braje, Paola Cappellaro Quantum sensors such as spin defects in diamonds have achieved excellent performance by combining high sensitivity with spatial resolution. Unfortunately, these sensors can only detect signal fields with frequency in a few accessible ranges, typically low frequencies up to the experimentally achievable control field amplitudes and a narrow window around the sensors' resonance frequency. Here, we develop and demonstrate a technique for sensing arbitrary-frequency signals by using the sensor qubit as a quantum frequency mixer, enabling a variety of sensing applications. The technique leverages nonlinear effects in periodically driven (Floquet) quantum systems to achieve quantum frequency mixing of the signal and an applied bias ac field. The frequency-mixed field can be detected using well-developed sensing techniques, such as Rabi and CPMG, with the only additional requirement of the bias field. We further show that the frequency mixing can distinguish vectorial components of an oscillating signal field, thus enabling arbitrary-frequency vector magnetometry. We experimentally demonstrate this protocol with nitrogen-vacancy centers in diamond to sense a 150-MHz signal field, proving the versatility of the quantum mixer sensing technique. |
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G00.00321: Quantum Simulation of Driven-dissipative Dynamics in Superconducting Circuits Qihao Guo, Botao Du, Ramya Suresh, Ruichao Ma Superconducting circuits have emerged as a leading platform for quantum simulation because of the high coherence and excellent controllability. Beyond the unitary evolution of quantum systems, quantum reservoir engineering opens a new window for exploring novel quantum phenomena in open systems, such as quantum thermodynamics and non-Hermitian physics. Here, we experimentally engineer tunable quantum reservoirs on the superconducting circuits platform with parametric couplings. In a 1D Bose-Hubbard lattice, we study the driven-dissipative dynamics and correlations inside the lattice when coupled to local gain and loss. We will also discuss experiments for creating and stabilizing long-range entanglement using non-local baths. Moreover, a scalable numerical simulation method we develop for these types of driven-dissipative dynamics based on quantum trajectory theory will also be discussed, which can also be useful for more topics in open quantum systems. To demonstrate its potential value, we will show how to apply this method to the optimization of dispersive readout. |
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G00.00322: Lindbladian quantizations of nonlinear nonconservative systems Dariel Mok, Andy Chia, Changsuk Noh, Leong-Chuan Kwek Nonlinear dynamical phenomena such as bifurcations, chaos and synchronization have led to important applications across many branches of science and engineering. Often, such systems rely on inherent nonlinear dissipation and pumping, which are in general difficult to model quantum mechanically. In this work, we present a comprehensive quantization scheme which can quantize a large class of nonlinear dissipative oscillators using Lindblad master equations. We then propose and prove the existence theorem for the Lindblad representation of nonlinear dynamical systems. This provides a systematic technique to quantize dynamical systems with arbitrary degree of nonlinearity. We also propose a heuristic approach called 'minimal-noise' quantization, which minimizes the number of Lindblad operators used. This reduces the relative amount of quantum noise which allows nonlinear effects to manifest more prominently. To highlight the utility of our scheme, we demonstrate various quantum bifurcations by engineering nonlinear dissipations, and quantize a large class of Liénard systems which exhibit quantum limit cycles. Our work opens up the prospect to harness the rich field of nonlinear dynamics for novel quantum technologies. |
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G00.00323: Scaling up 2D atom array platform with 87Rb Rydberg atoms Bruno Ximenez Rodrigues Alves In recent years, platforms of many interacting spins in a controlled environment have received increasing interest. They are useful for engineering spin Hamiltonians to study and model real-world complex problems in regimes that classical computers cannot exactly solve. Typically, the ability of a classical computer to efficiently solve the many-body dynamics decreases with the number of spins in the system. In this work we present our efforts to increase the number of individually trapped atoms in our 2D optical tweezer arrays. We report on a record of 361 atoms assembled in a geometrically user-defined array of tweezers in a ultra-high vacuum and cryogenic environment at about 4 K, which led to an atom lifetime in the tweezers of about 6000 s. The performance of the assembler was measured for arrays of 324 atoms, where a defect-free configuration was realized in 37% of the attempts. Achieving this result required equalizing the loading rate of the ensemble of traps, yielding a homogeneous top performance of 50-60% probability of trapping an atom in the tweezers. The equalization was implemented in a closed-loop optimization algorithm to compensate for optical aberrations in the trap beams by controlling the power on each trap generated by a spatial light modulator (SLM). |
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G00.00324: Precise Parameter Matching for Kerr-Cat Qubits Arne Schlabes, Mohammad H Ansari Kerr-Cat Qubits promise advantages with their biased noise architecture over regular qubits. Here we investigate the effect of a single photon drive and non-zero detuning on the Kerr-Cat qubit. Large detunings lead to fidelity losses during a gate, however they can be recovered after a fixed time period. Precise gate speed and parameter choices can point us to sweet spots, where fidelity and gate speeds are high. |
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G00.00325: Effect of Eccosorb IR Filters on Qubit Coherence Taryn V Stefanski, Lukas Johannes Splitthoff, Siddharth Singh, Figen Yilmaz, Martijn F. S. Zwanenburg, Christian Kraglund Andersen Superconducting qubits may suffer, despite extensive shielding, from interactions with residual noise photons arriving through signal lines to the device, which leads to qubit decoherence. To mitigate the photon population at the qubit frequency due to thermal radiation, attenuators can thermalize the electromagnetic environment at the sample stage. However, to prevent quasiparticle poisoning caused by Cooper pair breaking due to IR radiation, additional filtering is required. Such IR filters are routinely achieved using Eccosorb, a commercially available castable dielectric. We manufacture Eccosorb filters of various length and grade and characterize them at room and liquid nitrogen temperatures up to 67 GHz. Based on the obtained frequency dependent attenuation, we compute the residual noise photon population at base temperature and conclude on the preferred filter and attenuator configuration for superconducting qubit experiments. We validate the suggested microwave filtering for drive and flux bias lines by comparing coherent properties of transmon qubits for different filter configurations. |
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G00.00326: Bound states in single and double Y-junction quantum dot. Renat Sabirianov, Wai-Ning Mei, Ahmad Alsaad, Ather Mahmood, Abhilash Mishra, Christian Binek We present the solution of quantum-mechanical problem of a particle in Y-junction quantum dot. The single bound state with Dirichlet Laplacian is described. The bound state presence is examined for the case of junction being asymmetric, i.e. going from C3V to C2v group when the width of one of the ligament is increased. We further investigated the solution of two connected Y-junction with two bound states. These finding could be useful for building 2D two-level systems for quantum qubits or quantum waveguide applications. |
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G00.00327: Quantum simulations of simple field theories Gabriel J Barrios The progress of quantum computing has gained traction over the years due to its ability to surpass that of classical computers. Its concepts of superposition, interference, and entanglement are what make a quantum computer unique in the modern world. Implementation of this technology is multidisciplinary ranging from business, engineering, and other Research with Dr. Felix Ringer consists of the quantum simulations of simple field theories, such as quantum electrodynamics (QED), by using QisKit from IBM. My part in this line of work is to develop a Python program that evaluates these field theories using an operator to procure rotational angles. This part of the research acts as a stepping stone to implementing more complex theories such as quantum chromodynamics (QCD). |
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G00.00328: An Exploration of Solution Curves in Feedback-Based Quantum Algorithms Vicente Pena Perez, Matthew D Grace, Alicia B Magann There is a great interest in using parameterized quantum circuits to solve combinatorial optimization problems, and recently, the Feedback-based ALgorithm for Quantum OptimizatioN (FALQON) was introduced as an optimization-free framework for this purpose. In FALQON, circuit parameter values are set layer-by-layer according to a deterministic, measurement based feedback law. The output parameters can be plotted as a function of layer, producing FALQON solution curves. In this talk, I will explore the characteristics and generality of these curves with a focus on curves produced for solving MaxCut on regular graphs. In particular, I analyze the relationships between the solution curves and the corresponding problem instances, highlighting the observation that FALQON solution curves tend towards a universal form. Motivated by this observation, I will also discuss the transferability of solution curves across different MaxCut problem instances, and conclude with a discussion of how FALQON solution curves may be used to inspire quantum annealing schedules. |
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G00.00329: A State Distillation Method Using Quantum Imaginary Time Control for Solving the Generalized Eigenproblems Mengzhen REN, YU-CHENG CHEN, Alice Hu Finding eigenvalues of Hamiltonians has many important applications in generalized eigenproblems, such as calculating chemical reaction rates and approximating spectral densities of large matrices. While variational quantum methods (VQEs) and quantum Krylov subspace methods (QKS) have been used to estimate the ground and excited state energies of quantum many-body systems, different problems exist when computing excited states. VQEs face optimization problems, such as barren plateaus induced by high expressibility ansatz. QKS, whether it is QLanczos or QDavidson, faces the problem of long circuit depth and the requirement of extra ancilla qubits. Moreover, the number of measurements of the QLanczos increases exponentially with the expansion of the system. In this work, we proposed a state distillation method using imaginary time control which requires the quadratic form of the problem Hamiltonian and controls to adjust the order in which states vanish in imaginary time evolution. Using this state distillation, we can obtain states for constructing and solving a generalized eigenvalue problem to get the approximate eigenvalue and eigenvector of unknown excited states. The algorithm only needs an approximate energy of one of the eigenstates as the initial value to obtain excited states with energy higher than it. As the size of the system expands, it computes excited states with a quadratic increase in the number of measurements and little extra resources using the variational-ansatz based imaginary time method. In principle, using the state distillation method, our method is robust to control errors while solving the eigenspectrum of the n-local Hamiltonian matrix compared to the methods mentioned above, therefore more achievable for NISQ-era quantum computers. |
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G00.00330: Gravitational entanglement: Evidence for quantum gravity or a problem for causality? André Großardt Conceptual difficulties with the idea of gravitationally induced entanglement as a proxy for the quantization of gravity are discussed from various perspectives. A toy model interpolating between the Galilei-relativistic limit of mean-field semiclassical gravity and a de Broglie-Bohm description of Newtonian quantized gravity is presented as an explicit counter-example to claims that witnessing gravitationally induced entanglement between two particles would constitute a definitive proof for the quantization of the gravitational field. Furthermore, it is shown how - combined with prevalent heuristic ideas about the coupling of complex quantum systems to curved spacetime - the idea of gravitational entanglement poses an apparent conflict with relativistic causality, whose potential resolution points towards a novel decoherence channel for light-matter interactions due to gravitational effects. |
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G00.00331: Entanglement Dynamics for three and more Excitons in a Strained Graphene Sheet, embedded in a microcavity Gabriel Pimenta Martins, Oleg L Berman, Godfrey Gumbs, Yu (Yurii) E Lozovik We present a numerical analysis of the quantum entanglement between three and more qubits consisting of excitons in a strained graphene sheet, embedded in an optical microcavity. We analyze the time evolution of the entanglement for the system by calculating the time evolution of the negativity and the three-pi for the three-qubit case, both with and without cavity decay. We also provide a framework for the N-qubit entanglement analysis. Special attention is given to the evolution of the entanglement when the system starts out in the Greenberger-Horne-Zeilinger (GHZ) state, which is a strongly entangled state between three qubits with no pairwise entanglement. |
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G00.00332: A Hierarchy of Multipartite Correlations Based on Concentratable Entanglement Louis Schatzki, Guangkuo Liu, Marco Cerezo, Eric A Chitambar Multipartite entanglement is one of the hallmarks of quantum mechanics and is central to quantum information processing. In this work we show that Concentratable Entanglement (CE), an operationally motivated entanglement measure, induces a hierarchy upon pure states from which different entanglement structures can be certified. In particular, we find that nearly all genuine multipartite entangled states can be verified through CE. In the process we find the exact maximal value of CE and corresponding states for up to 18 qubits and show that these correspond to extremal quantum error correcting codes. The latter allows us to unravel a deep connection between CE and coding theory. Finally, our results also offer an alternative proof, on up to 31 qubits, that absolutely maximally entangled states do not exist. |
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G00.00333: Investigation of Quantum Memory Efficiency by Optimizing Light-Matter Interaction Safura Sharifi, Yaser Banad Efficient optical quantum memory is critical for various emerging quantum experiments ranging from linear-optical quantum computing to entanglement distribution and quantum networking. The efficiency of quantum memories based on atomic ensembles can be improved by temporal shaping of the optical signal field to be stored and the control field used to mediate the interaction when the signal bandwidths are smaller than the linewidths of the excited states participating in the memory transitions. However, adjusting the shape of intense broadband fields and various factors imposed by host materials make it challenging to find the optimal broadband operation in the quantum memory interaction. This work studies the performance of ?-type quantum memories at resonant and near-resonant frequencies for various parameters of control fields (optical power, arrival time, and duration) and host material properties (nuclear moment and isotopic purity). |
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G00.00334: Toward integrated photonic fusion gates for high-rate time-bin cluster state generation Matthew Yeh, Daniel R Assumpcao, Evelyn L Hu, Neil Sinclair, Marko Loncar Highly entangled photonic cluster states have emerged as an important resource for realizing numerous quantum technologies, including measurement-based quantum computing and loss-tolerant quantum networking. We design and fabricate an integrated photonic circuit composed of 2x2 3dB couplers, electro-optic switches, and delay lines on thin-film lithium niobate that can be used to manipulate time-bin photonic qubits. The circuit operates at telecommunication wavelengths, compatible with existing low-loss optical fiber networks. We measure and discuss the impact of important figures of merit for cluster state generation including insertion losses and switch extinction ratios. |
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G00.00335: Progress on the construction of an open access trapped barium ion quantum information processor Collin Epstein, Noah Greenberg, Xinghe Tan, Crystal Senko, Kazi Islam We present progress on the design and assembly of a trapped ion quantum information processor intended as an open access tool for the academic community. The QuantumIon project is building a quantum computation and simulation platform using trapped barium-133 ions that will provide users with an open, intuitive interface to high-performance quantum hardware to advance research in quantum information science experimentation and theory. We provide an overview of the processor design, optical engineering, atomic source development, and quantum control implementation for the platform. Additionally, we present recent advances in atomic source fabrication and progress towards trapping barium-133 ions in a surface trap. |
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G00.00336: Engineering spin-spin interactions with global beams Antonis Kyprianidis Trapped-ion quantum simulators typically generate spin-spin interactions by resonantly coupling to the normal modes of the ion crystal motion. The most common choice leads to a scaling of interaction strength with distance like a power law. In this work, we attempt to generalize on the accessible interaction graphs, if only global Raman beams are used, i.e. without individual addressing of each ion. We find that interesting cases other than power laws can be generated under conditions. We explore these conditions and speculate limitations for 1D and 2D ion crystals. |
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G00.00337: Modelling noise in global Mølmer-Sørensen interactions to quantum approximate optimization Phillip C Lotshaw, Kevin D Battles, Bryan T Gard, Gilles Buchs, Travis S Humble, Creston D Herold Trapped ions with multi-qubit Mølmer-Sørensen (MS) interactions offer unique capabilities for quantum information processing, with applications including quantum simulation and the quantum approximate optimization algorithm (QAOA). Here, we develop a physical model to describe many-qubit MS interactions under four sources of experimental noise: vibrational mode frequency fluctuations, laser power fluctuations, thermal initial vibrational states, and state preparation and measurement errors. The model parameterizes these errors from simple experimental measurements, without free parameters (after experimental noise characterization). We validate the model in comparison with experiments that implement sequences of MS interactions on two and three 171Yb+ ions. The the model shows good agreement after several MS interactions as quantified by the reduced chi-squared statistic χ2< 2. As an application, we examine QAOA experiments on three and six ions. The experimental performance is quantified by approximation ratios that are 91% and 83% of the optimal theoretical values. Our model predicts 0.93±0.02% and 0.92±0.06%, respectively, with disagreement in the latter value attributable to secondary noise sources beyond those considered in our analysis. We further compare experimental and simulated performance across heatmaps generated with varying algorithmic and experimental parameters, achieving χ2< 2 at six ions and a larger χ2 with three ions. Our model predicts that realistic experimental improvements to reduce measurement error and radial trap frequency variations would achieve approximation ratios that are 99% of the optimal. Incorporating these improvements into future experiments is expected to reveal new aspects of noise for future modeling and experimental improvements. |
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G00.00338: Fast Scrambling transition in sparse Clifford circuits Sridevi Kuriyattil, Andrew J Daley, Gregory Bentsen, Tomohiro Hashizume Quantum information scrambling is the process in which the initially localized quantum information gets delocalized due to many body dynamics present in the system. The question of efficient scrambling is especially relevant in experiments and noisy quantum simulators, where every applied gate is affected by noise and dissipation. In a local lattice, the underlying linear lightcone which governs the propagation of information limits the number of qubits that can be involved in any computation within the coherence time. By contrast, in systems with highly non-local interactions, it is possible for the information to spread exponentially rapidly. In this work, we study novel transitions between slow and fast scrambling regimes in Clifford circuits with tunable non-local sparse coupling. These models are experimentally accessible with 1D arrays of optically trapped neutral atoms, where non-local couplings are implemented by the rapid shuffling of atoms using optical tweezers. By tuning the sparse interactions and analyzing the degree to which information has been scrambled in the system using tripartite mutual information (TMI), we investigate this fast scrambling transition. |
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G00.00339: Analog and digital calculations on neutral atom based quantum computers. Lucas Lassablière Neutral-atom based quantum processing units is an attractive platform due to its large configurability and scalability. Tunable Hamiltonian can be created preparing arbitrary two-dimensional arrays of atoms and generating Rydberg-mediated interactions between atoms. A wide range of applications, ranging from optimization challenges to simulation of quantum systems, can be addressed either at the analog level (programming Hamiltonian sequences) or the digital level (programming gate-based circuits). We present and compare these two approaches and show how efficient they are in the noisy intermediate scale quantum era we are in. |
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G00.00340: Flip-chip design for coupling ultra-clean carbon nanotubes to surface acoustic waves Dublin Nichols, Jamie Berg, Vikram V Deshpande, Ethan D Minot, Bill Mitchell Hybrid quantum systems require the integration of multiple materials with complementary functionality into a single device. Since materials have unique fabrication constraints (deposition, lithography, thermal processing etc.), it is sometimes necessary to build components on separate chips. The components can then be coupled using a flip-chip geometry that sandwiches the two chips together. Recent success with flip-chip devices include ultra-clean gating of 2DEGs [1], generation of acoustoelectric current in graphene [2], and coupling of superconducting qubits with a bulk acoustic-wave resonator [3]. |
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G00.00341: Deep Reinforcement Learning for Robust Dynamical Decoupling Jner Tzern Oon, George Witt, Connor A Hart, Kevin S Olsson, Joseph Kovba, Blake Gage, Ronald L Walsworth Techniques that suppress the loss of coherence are widely applicable across the fields of quantum information and sensing. Seminal examples of dynamical decoupling protocols effectively protect a single qubit from its environment by applying a sequence of control pulses, often constructed from a small library of pulses. Depending on the complexity of the system, the length of a suitable decoupling sequence can vary greatly, often resulting in a prohibitively large search space. Modern advances in artificial intelligence have demonstrated success in problems of similar or greater depth (e.g., ∼10360 possible move combinations for games of Go). We utilize deep neural networks based on reinforcement learning algorithms to synthesize control sequences for robust dynamical decoupling and suppression of spin-spin interactions, with specific considerations for the nitrogen-vacancy center spin defect in diamond. |
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G00.00342: LASER SCIENCE
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G00.00343: Tunable Optical Parametric Amplifier for Visible Photocathode Excitation Brittany (Ying-Ying) Lu, Keith Wernsing, Sergio Carbajo Traditional particle accelerators use high-power ultraviolet, high repetition laser systems for photocathode excitation [1], but new photocathode materials, e.g. bi-alkali antimonides [2], with excitation bands in the visible spectrum (500-600 nm) are being developed with the promise of overcoming practical and scientific challenges [3,4]. These wavelengths do not correspond well to the harmonics of commercial Yb- and Ti-based lasers in the near-infrared (IR). As such, there is a need for a tunable visible laser source for photocathode characterization. We present numerical simulations of a tunable optical parametric amplifier for narrowband amplification, using an IR Yb-based laser front-end. In Type-I BBO pumped by narrowband 515 nm pulses, we amplify signal wavelengths between 1-1.2 µm, which can be converted to the desired visible wavelengths with high efficiency through second-harmonic generation. Ease of tunability is realized by adjusting the pump group delay and phase-matching angle. The resulting signal intensity gains are on the order of 1000, with good spatiotemporal profiles. The output signal pulses are well-suited for subsequent OPA and pulse stretching stages for producing consistently amplified femtosecond and picosecond pulses in a broader gain spectral region not seen in common laser materials. |
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G00.00344: Optical Design for a Laboratory-Scale Compact Free Electron Laser based on Inverse Compton Scattering Sean Tilton, Samuel W Teitelbaum, William S Graves, Arvinder S Sandhu, Sudeep Banerjee, Robert A Kaindl, Mark R Holl Here we will report the design of an optical undulator and its impact on the design of a compact x-ray free electron laser (CXFEL). X-ray Free Electron Lasers (XFELs) are light sources characterized by high brightness, full spatial coherence, and short pulse durations, which enable experiments that probe materials at the time and length scales of electronic and structural motion. At Arizona State University, the Compact X-ray Free Electron Laser (CXFEL) will employ emittance exchange of a diffracted electron beam to seed an Inverse Compton Scattering (ICS)-based XFEL, which will generate fully coherent radiation with an accelerator length of 10 meters. By using an optical undulator (i.e. ICS), the electron beam energy requirements are lowered, and the facility size will be greatly reduced along with its cost. Tuning the crossing angle between the electron beam and ICS laser enables a higher electron beam energy, while lasing in the soft x-ray regime, which is necessary for minimizing the space-charge effects present in low-energy accelerators. We present an optical design optimized for generating 1 nm (1.2 keV) radiation with a 30 MeV electron beam at a 30 degree crossing angle using a 10 TW peak power drive laser, which is within reach of high repetition rate commercial laser sources. |
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G00.00345: Developing an Open-Source Data Analysis Package for Optical Second Harmonic Generation Hussam Mustafa, Chunli Tang, Wencan Jin, Wenjiang Wang, Xiang Meng, Richard Osgood Optical second harmonic generation (SHG) is a process in which the frequency of light incident on a sample is doubled through its second-order nonlinear interactions with the material. It is a powerful tool to detect the symmetry breaking in a crystal by directly probing the nonlinear susceptibility tensor elements in a rotational anisotropic (RA) measurement. Recent years have seen the impressive development of the RA-SHG technique in discovering novel phases in quantum materials. Data analysis of an RA-SHG pattern is based on the simulation of nonlinear optical signals including electric dipole, electric quadrupole, and magnetic dipole response under given experimental geometry and point group symmetry of the crystal. An SHG simulation package will benefit the community by promoting the efficiency of data analysis. Here, we present our work of developing an open-source RA-SHG data analysis package. We develop a graphical user interface that can implement universal RA-SHG simulation of an arbitrary experimental geometry and the 32 crystallographic point groups. Our simulation will produce a functional model of RA-SHG data and a priori polar plot patterns with tunable tensor elements. Future implementation will integrate artificial intelligence (AI). AI will be used to collect experimental data from literature to establish a training database and generate polar plot patterns with predicted values of the tensor elements. |
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G00.00346: ATOMIC, MOLECULAR, AND OPTICAL PHYSICS
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G00.00347: Testing Physics Beyond the Standard Model by using Isotope Shift Spectroscopy Pallav Mohan Isotope's are atom's of the same atomic number but differ in the number of neutrons. This change primarily brings about two major changes in the atom: 1) with the introduction of additional neutrons there is an increase in the nuclear mass which changes the kinetics of the nucleus about the center of mass of the atom. 2) This addition of neutron changes the nuclear charge distribution, affecting how the electrons feel the effects of the nucleus. Both of these changes bring about a change in the atomic energy levels. And this change in the energy levels is what is referred to as Isotope Shift. |
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G00.00348: Optical Quasicrystal for Ultracold Atoms Emmanuel Gottlob, Lee C Reeve, Shaurya A Bhave, Jr-Chiun Yu, Bo Song, Ulrich Schneider Quasicrystals represent a rich middle ground between periodic and disordered materials. They possess perfect long-range order, yet they are not periodic. Hence many foundational concepts such as Bloch's theorem do not apply. Therefore, they exhibit exotic properties such as Anderson localisation, fractal energy spectra, or mobility edges. We have realized a two-dimensional optical quasicrystal for ultracold atoms, where the amount of (quasi-)disorder as well as interaction strength can be precisely controlled. We used this experimental platform to observe localisation phenomena, study its underlying fractality and connection to four-dimensional periodic lattices, as well as the resulting many-body phase diagram. In addition, we developed a Hubbard model able to describe this quasiperiodic lattice, without resorting to Bloch's theorem . Finally, we show how re-expressing the quasiperiodic Hubbard model in configuration space – where sites are arranged in terms of shape and local environment – provides valuable insight in the description of the infinite-size limit quasicrystal. |
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G00.00349: Interplay between quantum diffusion and localization in the atom-optics kicked rotor Shiv S Maurya tom-optics kicked rotor represents an experimentally reliable version of the paradigmatic quantum kicked rotor system. In this system, a periodic sequence of kicks are imparted to the cold atomic cloud. After a short initial diffusive phase the cloud settles down to a stationary state due to the onset of dynamical localization. In this paper, to explore the interplay between localized and diffusive phases, we experimentally implement a modification to this system in which the sign of the kick sequence is flipped after every M kicks. This is achieved in our experiment by allowing free evolution for half the Talbot time after every M kicks. Depending on the value of M, this modified system displays a combination of enhanced diffusion followed by asymptotic localization. This is explained as resulting from two competing processes—localization induced by standard kicked rotor type kicks, and diffusion induced by the half Talbot time evolution. The experimental and numerical simulations agree with one another. The evolving states display localized but nonexponential wave function profiles. This provides another route to quantum control in the kicked rotor class of systems. |
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G00.00350: Nonlocal four-body interactions with non-trivial topological properties in a one-dimensional system of ultracold bosons Philip R Johnson, Grennon J Gurney, Nathan L Harshman We present an effective theory of ultracold bosons in one dimensions with nonlocal four-body interactions and non-trivial topological properties. The effective interactions behave as a global (and scale-free) interaction between four particles that only turns on when separated pairs of particles come into contact. In the hard-core limit, the interaction creates a topologically non-trivial defect in configuration space, leading to multivalued wavefunctions with anyonic exchange statistics. It is one of only three possible few-body interactions with this property; the other two are local two-body interactions in two dimensions, leading to anyons with braid group statistics, and the local three-body interaction in one dimension, leading to anyons with traid group statistics. The nonlocal four-body interaction investigated here, which can be mapped to a system with two-body interactions in two dimensions, has conformal symmetry for any value of coupling strength leading to the possibility of probing spontaneous symmetry breaking of scale invariance. We analyze the model to identify spectral and dynamical signatures generated by the nonlocal interactions, anionic exchange statistics, and breaking of conformal symmetry. |
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G00.00351: Symmetry-protected topological lasing in a BdG system of pseudo-spin-1/2 bosons Hong Y Ling A topological laser is an active bosonic matter where the gain is distributed preferentially along the boundaries rather than in the bulk so that the mode competition will favor lasing in the edge modes, which are guaranteed by topology to be robust against disorder. We consider a (pseudo) spin-1/2 Bogoliubov-de Gennes (BdG) system, which is engineered, through a quench process, from a spin-1 Bose-Einstein condensate (BEC) in a honeycomb optical lattice. We use it to explore a host of issues concerning the symmetry-protected topological lasers which are characterized with stable bulk bands but unstable edge modes that can be populated at an exponentially fast rate. We express the criterion for topological amplifications in terms of an unconventional commutator between the number conserving and number nonconserving parts of the BdG Hamiltonian. We show that only when this “commutator” vanishes can a BdG system be made to operate as a symmetry-protected topological laser [Ling and Kain, Phys. Rev. A 104, 013305 (2021)]. We also carry out a quantitative study of the topological properties of our system in terms of topological invariants and symmetry classes, within the 38-fold way classification of topological phases in non-Hermitian systems [Ling and Kain, Phys. Rev. A 105, 023319 (2022)]. |
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G00.00352: Snapshot-based detection of hidden off-diagonal long-range order on lattices Fabian J Pauw, Fabian Grusdt, Annabelle Bohrdt, Felix A Palm, Sebastian Paeckel Revealing the existence of hidden off-diagonal long range order is believed to be a promising avenue towards identifying and characterizing topological order. In continuum fractional quantum Hall systems this can be accomplished by attaching gauge flux tubes onto the particles. Following the recent advances of cold atom experiments in optical lattices, probing this hidden, non-local order parameter with Fock-basis snapshots for lattice analogs is now within reach. Here, we demonstrate the existence of hidden off-diagonal long range order in quasi two-dimensional lattices in the ν=1/2-groundstate of the experimentally realistic isotropic Hofstadter-Bose-Hubbard model. To this end, we provide a MPS-driven, hybrid one and two-site snapshot procedure to sample the one-particle reduced density matrix and all particle positions simultaneously, emulating an experimentally feasible protocol. We present strong numerical indications for the emergence of an algebraic decay and discuss the resolution achievable using only few snapshots. |
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G00.00353: Progress toward optical control of mechanical geometry Tommy Clark We report experimental progress toward achieving strong control over the shape and effective mass of a mechanical mode [1] by optically trapping a single lattice site of a uniform phononic crystal. We expect this optically tunable defect to enable smooth localization of the spatial distribution of oscillating mass from the centimeter scale to the micron scale, enabling (among other things) qualitatively new dissipation studies, multimode Landau-Zener dynamics, and tunable optomechanical coupling to other systems on the lattice (e.g. spins or other cavities). |
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G00.00354: Radiation pressure based lock-in amplifier for quantum metrology Shruti Jose Maliakal, Aaron Markowitz, Christopher Wipf, rana X adhikari A phase-sensitive amplifier could be useful for several quantum metrology applications, e.g. in future gravitational wave detectors to protect the injected squeezing against decoherence caused by readout losses. Such a fully coherent amplifier using opto-mechanics that operates beyond the Heisenberg limit could be realized in a traveling wave optical cavity with one or more mirrors also serving as the mechanical oscillator engineered with suitable susceptibility. Here, we describe a tabletop experiment to demonstrate such phase-sensitive amplification: the opto-mechanical nonlinearity is a gram-scale mirror on a cantilever which is in a triangular optical cavity with no detuning. We discuss, in particular, the noise budgeting and use of a Mach-Zehnder interferometer with two such cavities for a macroscopic quantum-limited tabletop experiment in the audio frequency band. |
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G00.00355: Towards Raman Cooling in Erbium Doped Microresonators Danielle Woods, Elizabeth A Goldschmidt, Gaurav Bahl Optical excitation of matter commonly results in heating processes due to light absorption and inelastic phonon production processes such as Raman scattering. Optical cooling of solids has been achieved for certain materials through processes dependent on the sample’s electronic structure or through optical engineering. However, fluorescent cooling of any solid remains a challenge that has not been fully solved. We propose a new approach for achieving optical cooling in solids using whispering gallery modes. Optical absorption of rare-earth dopants in a micro-resonator is used to eliminate the Purcell enhancement of the heat-producing Stokes light scattering in a high-Q resonator with large Purcell enhancement of the phonon-absorbing Anti-Stokes scattering. We use several methods to fabricate erbium-doped Silica microsphere resonators with Q factors of 10^7, evanescently coupled to a biconical tapered fiber waveguide. We measure the effect of erbium absorption on the resonator Q for spontaneous Raman scattering. We will align the silica Stokes peak with the erbium absorption, thus reducing the ratio of Stokes to Anti-Stokes emission in our sample and leading towards possible net cooling effects. We will then measure the resultant effect on Stokes and Anti-Stokes emission due to our device’s Purcell enhancement and the coupled Rare-Earth atoms’ absorption. |
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G00.00356: Dissipative dynamics of an impurity with spin-orbit coupling Alberto Cappellaro Spin-orbit coupling (SOC) plays a central role in topological phases of matter. In reality, all of these topological materials are coupled to some dissipative environment, which affects the robustness of the phase. Surprisingly, SOC and dissipation are rarely considered together, which hinders our understanding of the interplay between the two phenomena. Here, we fill this gap by considering dissipative dynamics of a spin-orbit coupled particle in one dimension. |
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G00.00357: Simulation of Open Quantum Systems via Low-Depth Convex Unitary Evolutions Joseph Peetz, Scott E Smart, Spyros Tserkis, Prineha Narang Current methods for simulating open quantum systems either rely on classical calculations, which suffer from exponentially scaling runtimes, or quantum approaches that are typically impractical for near-term purposes due to the additional qubit and gate sequences needed and the associated noise. We propose a method that addresses this issue by decomposing a quantum noise channel into unitary operations and then applying these on a quantum computer. The method does not require deep ancilla frameworks and thus can be implemented with lower noise costs. The scheme can be efficiently run in parallel, and for random-unitary noise channels, this mapping is exact. For general noise channels, we present methods which approximately capture the non-unitary dynamics, allowing us to efficiently characterize the system evolution for a variety of systems. |
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G00.00358: Fundamental Uncertainties in Nonequilibrium Atom-Field Interactions Daniel Reiche Atomic clouds represent one of the the main workhorses for modern and future quantum technologies. A precise understanding of their fundamental physical limitations is a crucial task in the strive for miniaturized and fully integrated quantum sensors. |
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G00.00359: Artificial Intelligence for Atom Interferometry (AI^2) Sanha Cheong, Sean Gasiorowski, Michael Kagan, Murtaza Safdari, Ariel Schwartzman, Maxime Vandegar, Natasha Sachdeva, Yiping Wang, Timothy Kovachy, Jonah Glick, Arthur Perce MAGIS-100 is a proposed experiment under construction at Fermilab which will use interference fringes imprinted on cold atom clouds to sense physics signals, such as mid-frequency band gravitational waves and ultralight dark matter. To maximize the reach of this new experiment, a sophisticated set of tools must be developed for imaging, data reconstruction, and simulation. Modern machine learning/AI techniques offer innovative and powerful solutions to this diverse set of problems. In this poster, we present 3D reconstruction techniques for atom clouds using a differentiable ray-tracing simulator in conjunction with methods from modern neural rendering. Such techniques, used along with a recently developed light-field imaging device [arXiv:2205.11480], enable 3D reconstruction of cold atom clouds in a single camera shot. We further present a differentiable atomic simulator, which characterizes a dominant experimental systematic via a gradient-based fitting of wavefront aberrations in the lasers used for the interferometry. Several extensions to the above work are also discussed. |
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G00.00360: Momentum-correlated scattering spheres with macroscopic depletion in a Bose-Einstein condensate (BEC) Annesh Mukhopadhyay, M.K.H. Ome, Sean Mossman, Qingze Guan, D. Blume, Peter W Engels This work describes a combined experimental and theoretical study of momentum-correlated quantum mechanical scattering between atoms in a dilute-gas Bose-Einstein condensate. We focus on condensates with high enough densities such that a very rich sequence of multiple scattering events has to be taken into account. In our experiments, we generate a superposition of two different momentum states and image the resulting scattering effects in time-of-flight imaging. Scattering between particles in the same spin state or in different states can be induced. Our beyond-mean-field framework takes scattering cascades into account and qualitatively reproduces experimentally observed scattering spheres. A systematic study of quantum depletion and correlated scattering as a function of the initial population imbalance shows a surprising complexity of the dynamics even in conceptually simple experimental configurations. |
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G00.00361: Applications of the Hubbard wheel: Quantum non-demolition readout and the role of disorder in an ensemble of qubits Reja H Wilke, Thomas Köhler, Felix A Palm, Sebastian Paeckel Easily realizable and scalable setups involving a center site with extensively scaling coordination number are important in quantum information. Recent work on a system of hardcore bosons on a wheel geometry, known to form a Bose-Einstein condensate, introduced a mechanism stabilizing a one-dimensional quantum many-body phase in the presence of nearest-neighbor interactions via the protection of an emergent Z2 symmetry. In this talk, I'll discuss the effect of further perturbations, relevant in more realistic setups in quantum simulation and central spin systems. Furthermore, I'll introduce a probe site for quantum non-demolition readout of many-particle states, allowing to predict the state of the BEC on the wheel. These novel theoretical insights will facilitate experimental realizations and interesting applications in various quantum platforms. |
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G00.00362: Optical Vortex emitted by Classical Radiation Dumping due to Classical Van Hove singularity near Cut-off frequency of a Waveguide Yuki Goto, Tomio Y Petrosky, Satoshi Tanaka Classical radiation dumping has been a controversial subject because of an acausal solution of the Lorentz-Abraham (LA) equation that involves the third derivative in time. This is in contrast with quantum mechanics where the second quantization formulation on the radiation process due to the quantum transition of a charged particle has been exactly solved without any contradiction to the fundamental laws of physics in the well-known Friedrichs-Lee model. We have shown that the classical radiation dumping is also analyzed without any contradiction to the fundamental laws by classicizing the commutation relation of the annihilation and creation operators to the Poisson bracket of the normal modes of the classical field [1]. In this talk we apply this classical formulation to the emission process of an optical vortex with an angular momentum from a cyclotron motion of an electron in a cylindrical waveguide. The optical vortex from a cyclotron radiation has been experimentally observed [2]. We will show an interesting mechanism of emission of the optical vortex due to the Van Hove singularity of the density of state of the classical electro-magnetic field appearing at the cut-off frequencies of the waveguide. This new mechanism of emission process cannot be described in terms of the LA equation, because one cannot use the perturbation analysis performed in the LA equation, due to the Van Hove singularity. |
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G00.00363: Dispersion-engineered SOI waveguide-based telecom-band quantum light sources Joyee Ghosh, Shivani Sharma, Vivek Venkataraman The development of telecom-band integrated quantum light sources is an essential step towards deploying large-scale all-optical quantum computation and fiber-based communication networks. SOI (silicon-on-insulator) waveguides are more amenable to on-chip integration due to the low-cost and mature fabrication technology, and smaller device footprint as compared to chi(2) waveguides. Silicon’s high nonlinear coefficient along with a narrow and well-defined spontaneous Raman spectrum are added advantages for building quantum light sources with high spectral brightness and purity. Here, we theoretically explore quantum state engineering for direct generation of spectrally-pure (purity ~ 95%) heralded single photons, and also broadband (~60-nm around 1550-nm) polarization-entangled photon pairs (concurrence>0.96), at telecom wavelengths by tailoring the waveguide dispersion in silicon nano-waveguides and optimizing other parameters like pump wavelength and bandwidth. |
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G00.00364: A Two-Photon Investigation of Nonlinear Sample Properties Olivia R Green, Cody C Leary We modeled the Hong-Ou-Mandel effect for a two-photon state modified by a nonlinear sample interaction and studied how the interaction with a sample material affected the output coincidence signal. We found expressions for coincidence detections as a function of time delay between Hong-Ou-Mandel input paths. We find that frequency-independent phase shifts between interferometer arms have no effect on the coincidence signal, while frequency-dependent time delays do. |
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G00.00365: Turbulence-free two-photon beats from incoherent thermal radiation in double-slit interferometer Binod Joshi, Thomas A Smith, Yanhua Shih It is well known that in a classic Young’s double-slit interferometer, when the separation of the double-slit, d, is greater than the spatial coherent length, lc, of the field, no first-order interferences are observable from the spatially incoherent fields. We report a double-slit interferometer setup that is able to observe two-photon interference, a pair of randomly created and randomly paired photons interfering with the pair itself, from these incoherent fields, including two-photon beats. The light source of the interferometer emits incoherent fields in thermal state with two colors, one Green one Red, with difference between their frequencies ωG − ωR being much greater than the response frequency of the detectors. Certainly, no first-order interferences, including first-order optical beats, are observable when the observation plane of the double-slit interferometer is scanned with two point-like photon counting detectors, D1 and D2. However, in the joint measurement of D1 and D2, second-order interferences for ωG and ωR, as well as for ωG − ωR are all observable as functions of the relative distance between D1 and D2. More interestingly, all these two-photon interferences, including the two-photon beats, are turbulence-free, i.e., any fluctuations in the index of refraction resulting from turbulence in the optical paths of the interferometer do not affect the interference pattern. This observation is fundamentally interesting and practically useful. |
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G00.00366: Heterogenous III-V diamond photonic platform for quantum network nodes based on neutral silicon vacancy centers in diamond Sean Karg, Alexander Abulnaga, Ding Huang, Sacha Welinski, Mouktik Raha, Zihuai Zhang, Paul Stevenson, Jeff D Thompson, Nathalie P de Leon Photonic integration with diamond-based color centers is a promising avenue toward enabling long-haul entanglement distribution, but previously studied color centers lacked the requisite environmental insensitivity for integration in nanofabricated structures [1]. We present a heterogeneously integrated III-V diamond photonic platform specifically designed for neutral silicon vacancy (SiV0) color centers. The SiV0 center has an array of highly desirable properties, such as long spin coherence and low spectral diffusion, that make it a highly suitable candidate for nodes in quantum networks [2,3]. We utilize a highly selective III-V dry etch and stamp transfer method and entirely avoid etching the diamond substrate, preventing material damage and spectral diffusion associated with diamond nanofabrication. Using 1D photonic crystal cavities and nonlinear frequency conversion in ring resonators, SiV0 emission can be Purcell enhanced and efficiently collected, while providing a source of telecommunication photons for long-haul fiber optic transmission. |
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G00.00367: Modeling Interference of a Two-Photon State Using Optical Pulses Kyla A Koos A pair of optical pulses incident on a Mach-Zehnder interferometer were modeled to explore the similarities and differences between interfering classical and quantum light. A time delay was modeled in one arm of the interferometer to vary the interference of the classical pulses. The resulting coincidence rates were modeled and compared to the quantum optical case of a two-photon input state, showing differences in interference pattern between quantum and classical light. |
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G00.00368: Ultra-thin WS2 waveguide for efficient light guiding and modulation Seong Won Lee, Jong Seok Lee, Woo Hun Choi, Su-Hyun Gong Optical waveguide has been studied to guide light over long distances with low losses while confining photon energy to a small area. In particular, the plasmonic waveguide has been spotlighted due to its ability to confine photon energy in a much smaller area. However, a severe propagation loss of a plasmonic guided mode due to the scattering at a rough metal surface and ohmic loss remains a crucial issue. Here, we propose exciton-polariton waveguide made of WS2 ultra-thin film (20 nm). Using theoretical simulations, we directly compared the WS2 waveguide with two conventional waveguides (silver waveguide and Si3N4 waveguide). Simulation results showed that the effective mode area of the WS2 waveguide is about half size of the Si3N4 waveguide whereas the propagation loss is about the half value of the silver waveguide. The characteristics of the WS2 waveguide was confirmed experimentally by coupling a white light to the waveguide. Finally, we demonstrated a WS2 waveguide modulator based on pumping-power dependent polariton dispersion relations. Because of the large nonlinearity of the polariton system, efficient light modulation can be achieved even with a short length of the modulation (2 μm). The advantage of the WS2 waveguide are expected to contribute to the miniaturization of photonic devices in the future. |
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G00.00369: Magnetic field sensor using a Nitrogen Vacancy center in Diamond at Liquid Nitrogen TemperatureJoseph Lydon, Sagar BhandariDepartment of Physics and Engineering, Slippery Rock University, Slippery Rock, PA 16057 Joseph D Lydon We present our work on a magnetometer probe capable of measuring local change in magnetic field at liquid Nitrogen temperature. The magnetometer is based on Nitrogen Vacancy (NV) center in diamond. The negatively charged state of NV center in diamond consists of a nitrogen atom replacing the carbon atom next to a vacancy with spin state of 1. When irradiated by a 532 nm laser, the fluorescence of NV center is at 637 nm. The intensity of fluorescence depends on the spin state of the NV center before irradiation. The spin state of the NV center depends on the local magnetic field via Zeeman interaction. By using a proper sequence of laser and microwave pulses and measuring the fluorescence intensity, a highly sensitive magnetometer probe can be built. We report our progress and design of the magnetometer probe. The anticipated spatial resolution of the magnetometer is in the order of nanometers, with magnetic field resolution of nT. |
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G00.00370: A photonic integrated circuit for time-bin qubits Benjamin E Nussbaum, Ujaan Purakayastha, John Floyd, Christopher C Evans, Joel M Hensley, Paul G Kwiat Scalability is a significant challenge for expanding quantum networks. In the classical internet, information is encoded in the presence or absence of light in an optical fiber at a given time. A natural analog for quantum information is time-bin encoding: a photon can be in one (or a coherent superposition) of two (or more) time bins, measured by the relative delay in arrival time at a detector. Fiber-based and free-space optical time-bin systems have a significant system footprint, and require repeated precise alignment or stabilization to counteract drift and maintain performance. We use a lithium niobate photonic integrated circuit (PIC) to analyze time-bin qubits at 1560 nm. The PIC contains a balanced Mach-Zehnder interferometer (MZI) and an unbalanced MZI. The path imbalance in the latter is such that the 'early' and 'late' time-bins are separated by 200 ps. Sending such a two time-bin state, generated with an equivalent interferometer with a matching path imbalance, as an input to the device yields three time-bins at the output. The final middle time bin in this case corresponds to a superposition of the long-short and short-long path combinations through the two unbalanced interferometers, which exhibit interference when the path length imbalances are matched. By adjusting the switching ratio in the first MZI, we can equate the amplitudes of these processes, thus maximizing the achievable interference visibility. Varying the relative phase, and with polarization filtering, we observe a maximum visibility of ~83%. Improved performance is expected with the inclusion of active phase stabilization, using a narrowband CW laser. These measurements are an important step toward scalable quantum networking. |
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G00.00371: Electro-optic effect of graded-pitch chiral photonic structures under oblique illumination Laura O Palomares, Juan Adrian Reyes We studied theoretically optical spectra when circularly polarized light obliquely impinges on a slab of a chiral photonic structure with linearly and uniformly spatial varying pitch. The material that we considered locally has a ar{4}2m point-group symmetry and presents Pockels effect, hence, we controlled optical spectra by a low frequency (DC) electric field applied along the nonhomogeneity axis. The spectra display a Bragg-type broadband, where the edge wavelengths of the photonic band are expressed in terms of the medium parameters and the external electric-field magnitude. This allows us to select the region of the electromagnetic spectrum, where the band could become as broad as we choose. We studied three samples with iridescent, silver, and golden colors due to their reflection properties. We observed an enhancement as well as a broadening of the optical band by the application of the electric field. We found that, under certain conditions, when the optical band is practically absent, a very broad band could be created (comparable to the whole visible spectrum) when a DC electric field is applied. This is the result of electro-optic contributions in the permittivity tensor elements, which give rise to a tremendous increase in both the rotatory power and dichroism. Therefore, these media could be used as electrically controlled broadband frequency and polarization filters. Moreover, we observed the usual blueshift of the band as the incidence angle of light increases and an asymmetry in the reflection band amplitude as the incidence angle of the light increases, depending on whether the pitch increases or decreases and the pitch gradient; which endows the sample with different reflection colors for different gradients and incidence angles of the light. The asymmetry in the reflection band vanishes as the magnitude of the electric field increases. |
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G00.00372: Non-Hermitian Photonics in a Heterogenous Photonic Molecule David Sharp, Minho Choi, Hao Nguyen, Arnab Manna, Johannes E Fröch, Brandi Cossairt, Arka Majumdar Nanophotonics offers an intriguing avenue to study non-Hermitian physics. Of particular interest is breaking the gain-loss balance in a photonic molecule consisting of coupled nanocavities to lower power thresholds for nanolasers. Previous work has focused on homogeneous photonic molecules consisting of coupled ring resonators integrated with gain material; however, the large mode-volumes of ring resonator cavities limits the light-matter coupling strength. In this work, we utilize heterogeneous photonic molecules wherein a low mode-volume nanobeam photonic crystal cavity is coupled to a ring resonator. We further utilize deterministic positioning of colloidal nanocrystal gain material to asymmetrically couple gain material only to the nanobeam cavity, thereby inducing gain solely in the nanobeam cavity. We explore non-Hermitian physics in the heterogeneous photonic molecule by modulating the system's gain-loss balance between the nanobeam cavity and the ring resonator. |
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G00.00373: Splitting Indistinguishable photons: Using Linear Optics to exceed the limit of Photon Blockade Harjot Singh, Jasvith Basani, Edo Waks Photonics has been established as an attractive platform for quantum information processing. However, lack of photon-photon interactions prevents the implementation of certain desirable quantum operations. Scattering photons off a mediator such as a Two-Level Emitter (TLE) coupled to a waveguide has been shown to create photon-photon interactions. However, time-energy uncertainty prevents the implementation of high-fidelity quantum operations with a single TLE. For example, the photon blockade effect exhibited by a TLE is unable to deterministically route two indistinguishable input photons to different output ports. We show that the use of optimized linear optics can be used to tune the inference between the output modes of the TLE to improve beyond the limitation imposed by photon blockade. Via numerical optimization, this limit can be exceeded to reach net routing efficiencies approaching 92%. Since the interference introduced by linear optics strongly correlates to the temporal profile of the incident photons, we employ wave shaping to further maximize the routing efficiency. Our results prove that systems built with TLEs and linear optics open up prospects of achieving high fidelity quantum operations. |
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G00.00374: Strain tuning of VSi in SiC via waveguide bending Timo Steidl, Marcel Krumrein, Di Liu, Petr Siyushev, Roman Kolesov, Rainer Stöhr, Jawad Ul-Hassan, Florian Kaiser, Jörg Wrachtrup Photonic interference is a proven pathway to scale up quantum systems [1]. Interference requires indistinguishable photon emission of multiple emitters, which can – in principle - be accomplished using Stark shift tuning. To avoid crosstalk between multiple devices on a single chip, we propose to use strain tuning for compensation. |
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G00.00375: Tunable photon-mediated interactions between spin-1 systems Cristian Tabares, Erez Zohar, Alejandro Gonzalez-Tudela Quantum simulators are highly controllable devices that exploit quantum effects to answer questions about another system. They can be built using ultracold atoms, superconducting circuits or atoms interacting with nanophotonic structures [1]. In this last system the nanophotonic environment can be tailored to generate exotic photon-mediated interactions between atoms [2], allowing the exploration of a wide range of physical models. However, these atoms have been typically considered as two-level systems, limiting the models explored [3]. Our work considers the full atomic hyperfine structure to go beyond this and study effective spin-1 interactions between the emitters, where Raman-assisted transitions allow a mapping to the Ising or XX spin-1 interactions. These results could be interesting both in quantum simulation (to study spin chains or even simulating some lattice gauge theories) and quantum computation (to obtain quantum gates between qutrits). |
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G00.00376: Escape from potential traps assisted by the Casimir-Polder force fluctuations Konstantinos Tsoukalas Continuous progress in nanotechnology leads to technologies with ever smaller features, with size down to a few nanometers. In this regime, quantum effects that used to be the subjects of theoretical physics become technologically important and can add functionalities or induce failures to nanodevices. Such is the Casimir force that has recently attracted attention because of its effects on nanoelectromechanical systems. However, much less studied are the fluctuations of the Casimir force, which can be strong enough to influence systems in which the mean value of the Casimir force is negligible. |
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G00.00377: Impurity with a resonance in the vicinity of the Fermi energy Mikhail Maslov, Mikhail Lemeshko, Artem Volosniev We study an impurity with a resonance level whose position coincides with the Fermi energy of the surrounding Fermi gas. Such an impurity causes a rapid variation of the scattering phase shift for fermions at the Fermi surface, introducing a new characteristic length scale into the problem. We investigate manifestations of this length scale in the self-energy of the impurity and in the many-body density function of the bath. Our calculations reveal a model-independent deformation of the density of the Fermi gas, which is determined by the width of the resonance. To provide a broader picture, we investigate time evolution of the density in quench dynamics, and study the behavior of the system at finite temperatures. We also briefly discuss implications of our findings for the Fermi-polaron problem. Overall, our results are relevant for studies that involve quasiparticle interference methods or fermion-mediated RKKY-type interactions in Bose-Fermi mixtures.
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G00.00378: Quadrupole-spin-charge separation and magnetic phases of a 1D interacting spin-1 gas Felipe Reyes Osorio, Karen Rodriguez Ramirez We study the low-energy collective properties of a 1D spin-1 Bose gas using bosonization. After giving an overview of the technique, emphasizing the physical aspects, we apply it to the S=1 Bose-Hubbard Hamiltonian and find a novel separation of the quadrupole-spin-charge sectors. Additionally, through the single particle spectrum, we show the existence of the superfluid-Mott insulator transition and the point at which the physics are described by a Heisenberg-like Hamiltonian. The magnetic phase diagrams are found for both the superfluid and insulating regimes; the latter is determined by decomposing the complete Heisenberg bilinear-biquadratic Hamiltonian, which describes the Mott insulator, into simpler, effective Hamiltonians. This allows us to keep our methods flexible and transferable to other interesting interacting condensed matter systems. |
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G00.00379: Condensation energy for a Bose gas with gaped quadratic dispersion relation in 1, 2 and 3 dimensions Miguel A. Solís, Juan J Valencia In superconductivity it is common to calculate the condensation energy (CE) which is the difference between the superconducting and normal Helmholtz free energies. |
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G00.00380: Demonstrating Optimal Ion Transport Protocols and Quantum Control on Surface Electrode Ion Traps Sahra Ahmed Kulmiya Trapped ion qubits achieve excellent coherence times and gate fidelities, well beyond the threshold for fault tolerant quantum error correction. One route towards scalability is the coherent control and transport of ions between different zones on a microfabricated surface trap. A current challenge in ion transport is speed and fidelity. The transport operations should be as fast as possible to speed up quantum computation, as well as slow (adiabatic) in order to preserve the internal qubit state. Through simulation of trapping potentials and ion dynamics, we can observe the effects of static and dynamic potentials on the ions motional state and investigate various shuttling protocols on an X-junction surface trap. We demonstrate various transport and ion-reconfiguration protocols towards fast, coherent quantum control. |
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G00.00381: Noise-resistant quantum memory enabled by Hamiltonian engineering Lei Jing The mesoscopic nuclear spin ensemble in quantum dots, which consists of 10^4 to 10^6 nuclear spins and has a coherence time of up to milliseconds, is a promising candidate for a fast and scalable quantum memory. Coherently transferring the electron spin state to the collective nuclear spin state requires polarization of the nuclear spin ensemble. Nuclear spin noise can obstruct the transfer process and lower transfer fidelity especially at low nuclear polarization. Here we propose a new protocol for performing noise-resisted quantum state transfer by employing Hamiltonian engineering. By decoupling the nuclear spin noise from the electron with a sequence of pulses, while maintaining the necessary flip-flop interaction, our protocol guarantees high fidelity quantum state transfer at much lower nuclear polarizations. A numerical simulation that we conducted shows a fidelity over 80% can be reached as nuclear polarization drops to as low as 30%. This Hamiltonian engineering methods may also be helpful for future explorations in quantum memory and DNP in other systems such as NV color centers, doped-ion crystals and atomic ensembles. |
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G00.00382: Ground state energy of a weakly interacting Bose gas in a 1D crystal with vacancies Miguel A. Solís, Emilio I Guerrero, Omar A Rodriguez For a weakly interacting Bose gas inside an imperfect one-dimensional crystal, we study the effect of vacancies on its ground state properties. To do this, we solve the corresponding Gross-Pitaevskii equation using the ``Gradient Flow with Discrete Normalization" method. |
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G00.00383: Quantum phases of Rydberg atoms on a Shastry-Sutherland lattice Fangli Liu, Milan Kornjaca, Mkhitaryan Vahagn, Sergio Cantu, Tommaso Macri, Pedro Lopes, Shengtao Wang, Nathan Gemelke, Arnab Banerjee, Alexander Keesling, Vladimir M. Shalaev, Alexandra Boltasseva We explore the phase diagram of Rydberg atoms in a frustrated Shastry-Sutherland lattice. Using the density matrix renormalization group, we map out a rich phase diagram in a three-dimensional parameter space that is naturally realizable in current Rydberg atom platforms. In particular, besides a plethora of classical phases, we show the presence of phases stabilized exclusively by quantum fluctuations. This includes an ordered phase and a quantum dimer phase. We employ order parameter symmetry analysis to show the presence of novel quantum critical points. Lastly, we study the feasibility of quantum phase preparation in real experimental systems. |
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G00.00384: Achieving the Continuum Limit of (1+1)D Lattice Quantum Electrodynamics in Cold-Atom Quantum Simulators Conall V McCabe, Matjaz Kebric, Fabian Grusdt Advances in cold-atom simulators has allowed the implementation of a Z2 lattice gauge theory in optical lattices where phenomena inherent of Quantum Electrodynamics (QED) can readily be observed. However a procedure for reliably taking the ZN → U(1) limit necessary to recovery the continuum theory in quantum simulators has remained elusive. |
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G00.00385: Coherent pair driving as a resource for many-body physics Emmanouil K Grigoriou, Carlos Navarrete-Benlloch Under adequate conditions, many body quantum systems are known to form macroscopic phases displaying exotic properties. Superfluid zero viscosity or superconducting infinite conductivity still hold the promise for key technological breakthroughs. Such expressions of collective behavior emerge from the complex interplay between quantum processes in the limit of an ever increasing number of degrees of freedom, quickly becoming numerically intractable and setting the stage for the appraising of quantum simulators. As a result, a lot of effort has been devoted to the understanding of the conceptual ingredients underlying emergent physics and an active area of research is concerned with the experimental generation of these phases in controlled environments. Today, modern experimental platforms allow for the implementation of processes not traditionally considered in a many body context. Processes that do not conserve the number of excitations such as coherent pair drivings are the focus of this work. We show how these new ingredients, lead to a novel kind of Bogoliubov inestability, inducing new phases in spatially non extended systems or enriching the phase diagram of already well established models in unexplored ways. Among others, we observe the enhancement of lattice supersolidity in the extended Bose-Hubbard model. |
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G00.00386: Fabricating Half-wave Plate using Two-Photon Polymerization Technique Yangheng Jizhe, Andrew Lininger, Giuseppe Strangi Our group is dedicated to fabricating otpical metamaterials using the technique of Two-Photon-Polimerization (TPP) with Nanoscribe. We have tested the limits of Nanoscribe to produce nanopillar structures, reported aspect ratios up to 5, with a minimum lateral resolution of 300 nm, and been using GWL scripts to extend the capabilities of nanoscribe beyond traditional print sets. Furthermore, we have successfully printed structures incorporating large scale arrays of arbitrary 2d elements other than cylindrical pillars (we have printed tori ). Pillars and toris have been used in metalenses as building blocks, thus our results will provide a pathway for the reliable and faster deposition (than standard e-beam lithography) of optical metamaterials. |
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G00.00387: Observation of Radiative double-electron capture (RDEC) by F9+ ions in collisions with single-layer graphene Asghar Kayani Radiative double-electron capture (RDEC) occurs when the capture of two electrons by a fully stripped ion is accompanied by the simultaneous emission of a single photon. This process, fundamental in atomic collisions, is considered the inverse of double photoionization by a single photon. RDEC has been successfully studied with F9+ ions for a [LMDS(1] single-layer of graphene1[LMDS(2] . A graphene target (∼0.35 nm thick) was mounted on a silicon nitride supporting grid (200 nm thick) consisting of ∼6400 holes of 2 µm diameter on a 200 µm thick hexagonal silicon substrate with a 0.5 x 0.5 mm aperture. For single-layer graphene, [LMDS(3] the foil thickness is close to that of a [LMDS(4] gas target and about a hundred times smaller than the thin-foil carbon. A Si(Li) x-ray detector placed at 90° to the beam[LMDS(5] detected the emitted x rays in coincidence with magnetically separated outgoing charged particles counted with silicon surface-barrier detectors. In the present work, the RDEC measurements have been repeated with single-layer graphene as well as a sample that had no graphene on it. X rays attributed to RDEC were seen for two separate graphene samples, while no RDEC x rays were observed for the sample without graphene, [LMDS(6] as expected. These measurements were just completed and analysis is underway, so the results will be reported later. Cross section values, which will be obtained from the data, will be compared with our previous gas target2 and C-foil target3. |
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G00.00388: Frequency-comb-based multidimensional coherent spectroscopy of systems with long-lived excited states Bachana Lomsadze, Skyler Weight, Peter Hovland Frequency-comb-based multidimensional coherent spectroscopy is a powerful optical method for studying nonlinear optical properties of samples with narrow resonances. It enables the measurement of multidimensional coherent spectra rapidly and with high spectral resolution. However, for some samples (especially cold atoms and molecules) the dephasing times are longer than the repetition periods of the excitation lasers and hence the nonlinear signals generated in the sample by the subsequent laser pulses will interfere with each other. Here we investigate this behavior and show its effect on multidimensional coherent spectra by solving the optical Bloch equations. |
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G00.00389: Band structure for relativistic charge carriers submitted to a helical electric field Daniel Martinez, Juan Adrian Reyes, Carlos Avendaño We study the relativistic dynamics of electrons submitted to a uniform harmonic electric fields longitudinally applied to the electron velocity. In order to obtain explicitly the set of time-dependent equations for the bi-spinors components, we write down the corresponding Dirac equation for this system. By performing a suitable transformation to this set of equations, we get a matrix equation whose eigenvalues can be found directly. We found analytically the band structure and show a break of degeneracy and the existence of three bands: two total and one partial. The thicker band preventing from the Schwinger mechanisms can be shortened by proper combination of the frequency and amplitude of the applied electric field. |
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G00.00390: Numerical Analysis for Cavity Quantum Electrodynamics Using Matrix Product States and Numerical Mode Decomposition Christopher J Ryu, Dong-Yeop Na, Weng C Chew The multimode Rabi Hamiltonian describes a cavity quantum electrodynamical (QED) system, involving a two-level atom interacting with multiple quantized electromagnetic modes of the surrounding structure. Since this Hamiltonian is beyond the rotating-wave approximation, it is valid even in the ultrastrong coupling regime. However, there has been a problem of gauge ambiguities with the Rabi Hamiltonian due to the fact that it can be derived from two formally different but physically equivalent fundamental Hamiltonians. This problem has recently been resolved for single electromagnetic mode models. In this work, we mathematically and numerically verify this for multimode models. With this established, we combine the numerical methods, matrix product states (MPS) and numerical mode decomposition (NMD), for analyzing cavity QED systems. The MPS method is used to efficiently represent and time evolve a quantum state, and to this end, the Rabi Hamiltonian is numerically transformed in a stable manner into an equivalent Hamiltonian that has a chain coupling structure, which allows efficient application of MPS. The technique of NMD is used to extract the numerical electromagnetic modes of a general inhomogeneous medium, and this allows one to construct the quantized field operator for an arbitrary electromagnetic environment. As a proof of concept, this combined approach is demonstrated by analyzing 1D cavity QED systems in various settings. |
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G00.00391: Theoretical Investigation of wave functions and fine structure of ground state configuration 5d36s2 of Tantalum atom. Rimsha Shaikh Hydrogen is the only element for which Schrodinger’s equation gives an exact result. For transition metal with large atomic number and rare-earth metals Russel Saunders coupling is still suitable. When a number of electron is increased, different type of perturbation added in Hamiltonian, and it becomes complicated to calculate exact hamiltonian for multielectronic system. In this study, coefficient of fractional parentage method is used to calculate the wavefunctions of Tantalum. The coefficient of fractional parentage method shows the contribution of parent atom in making final terms. |
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G00.00392: Effect of stacking layers, disc size, twist angle and vertical electric field on the band gap of multilayer graphene quantum dots Xian Wang First-principles calculations are used to study the joint modulation of the number of stacking layers, disc size, twist angle and vertical electric field on the band gap of multilayer graphene quantum dots. The structure and properties of multi-layer graphene quantum dots have many degrees of freedom in modulation. In addition to the usual quantum confinement effect, multi-layer assembly, interlayer twist, and external vertical electric field are all effective modulation methods. The above-mentioned complex operational elements lead to a lot of complexity, and the physicochemical mechanism therein remains unclear. In this work, single-layer graphene quantum dots with different diameters are used as the building block to construct the twisted multilayer graphene (TMGN, N is the number of stacked layers) quantum dot structures. Density functional theory calculations are used to study the variation of quantum dot band gap with stacking thickness, interlayer twist angle and vertical electric field. Studies have shown that the band gap of TMGN varies with θ. For a specific θ, the band gap of TMGN continuously decreases with increasing N, and reaches a stable value when N = 6. The band gap of TMGN reduces with the increasing field strength. Under the applied vertical electric field, the band gap change caused by the electric field increases significantly with N. Our research proposes a method to realize the quasi-continuously controllable band gap of multilayer graphene quantum dots by synergistically controlling the number of layers, size, interlayer twist angle of the quantum dots and electric field strength. |
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G00.00393: Valley Dependence of Photo-induced Vortex States in Transition Metal Dichalcogenides Connor Meese, Lauren I Massaro, Mahmoud M Asmar Subjecting transition metal dichalcogenides (TMDs), such as Molybdenum Disulfide (MoS2), to a monochromatic circularly polarized light leads to the observation of interesting optically induced phenomena such as valley-selective circular dichroism and a valley-selective optical Stark shift. Traditionally, light polarization, frequency, and amplitude have been used to tune phases of matter via Floquet engineering. However, additional degrees of tunability can arise from the spatial control of optical beams. Light-vortex beams are examples of such radiation sources since, in addition to polarization, they carry orbital angular momentum. Considering a monolayer TMD subjected to a monochromatic vortex-light beam, we analyze the possible appearance of valley-polarized quantum-vortex states in these systems. We obtain the Floquet Hamiltonian of the space-dependent system by identifying the light polarization and frequencies for which a total angular momentum characterizes the Floquet states, and we diagonalize the one-dimensional radial problem. We present our findings on the valley-dependent electronic vortex states and analyze their spin textures, topological properties, and real space extension. |
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G00.00394: STM Visualization of Ligand Adsorption on Silver Nanoparticles Qingyi Zhu, Kangkai LIANG, Liya Bi, Shaowei Li, Yufei Wang, Andrea Tao Being able to apply in many different fields such as physical sciences, agriculture, and medical sciences, nanoparticles become one of the most popular science research materials with a scale of 1 nm to 100 nm. Many new technologies have been used to study the nanoparticles, including the Scanning Tunnelling Microscope (STM), which can image the molecules' surface at the atomic level. Although STM has been widely applied in imaging the nobel metal surfaces, the molecular-scale resolution is usually hard to achieve when images in the nanoclusters are synthesized in solution. Here, we use a low-temperature, UHV STM to image silver nanoparticles of different sizes deposited on Au-coated Si wafers, and examine the orientation and density of the ligands on the silver nanoparticles. Our study provides a molecular scale characterization of ligand-metal interaction. |
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G00.00395: Detection of thermoelectric effects in magnetic metals by ac higher harmonics technique Junyi Wu, David G Cahill, Virginia O Lorenz Thermoelectric effects refer to the conversion of a temperature gradient into an electric signal in magnetic conductors. Anomalous Nernst effect (ANE) and anisotropic Seebeck Effect are thermoelectric effects that has been receiving increasing attention due to the development of spin caloritronics and topological material studies. In the measurements, external heater is the most common source of temperature gradient. We present an ac higher harmonics technique to detect thermoelectric effects in metal lines with temperature gradient induced by self-heating. We show that in Ni film, by Joule heating, it is possible to observe longitudinal and transverse thermoelectric effect in the second harmonics, separate from present longitudinal magnetoresistance signal, by using a lock-in detection technique with a circuit bridge. 3ω signals can be used to identify the heating. Besides film samples, our technique can also be applied to focus ion beam microfabricated element from bulk crystal. The ac higher harmonics technique provides a new path to probe the ANE in ferromagnets and anisotropic Seebeck Effect in antiferromagnets, promoting the application of spintronics devices. |
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