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 SS01: V: Poster Sessions II (1:30pm-3pm, PST)Poster Undergrad Friendly
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Room: Virtual Room 1 |
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SS01.00001: BIOLOGICAL PHYSICS | ATOMIC, MOLECULAR, AND OPTICAL PHYSICS | TOPOLOGICAL MATERIALS | SEMICONDUCTORS, INSULATORS, AND DIELECTRICS | SUPERCONDUCTIVITY . |
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SS01.00002: High-Speed Optical Microscopy Imaging of a Large Number of Spots of Tissue Samples and Detection of Cancer Using Artificial Intelligence (AI) Mousa M Alrubayan, Rajesh Shrestha, Prabhakar Pradhan Cancer is the leading cause of death worldwide, with almost 10 million deaths in 2020 alone. Cancer does not usually show symptoms until it has spread and is generally diagnosed at a very later stage. This late-stage diagnosis significantly reduces the chances of survival. Early diagnosis helps?significantly?in?detecting?and?treating?cancer. However, the?traditional?method of manual imaging and identification of?cancer tissue characteristics?is?time-consuming?and tedious.?The?search?for?a better alternative for?robust and?accurate?cancer?detection?requires?high-volume imaging and statistical analysis of cancerous?tissue.?In this study, we report high-speed optical transmission/ reflectance?imaging of tissue samples using Tissue Microarrays?(TMA) cancer/control?tissue samples. These images are analyzed using the?artificial intelligence?(AI) algorithm. A conventional Olympus BX61 motorized research-grade microscope and custom automatic scanning patterns are used for imaging. The?image analysis is then performed using the AI-based Convolutional Neural Network (CNN) algorithm. The?results?show?robust and?accurate detection of control and cancer?stages?of tissues. The potential for pathological applications of the technique in cancer detection?is?discussed. |
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SS01.00003: Toward Room-Temperature Mechanical Motion Driven by Quantum Radiation Force Noise. Jiaxing Ma We present progress toward building an optomechanical system where the motion of a “trampoline” mechanical device is dominated by the quantum radiation force noise (QRFN) of laser light circulating in a 50 microns-long fiber cavity. The cavity comprises two highly reflective fiber mirrors, achieving finesse ~10,000, and a 100-nm-thin silicon nitride “trampoline” mechanical device is mounted in the middle, such that it feels the “kicks” from photons circulating in the cavity. As of October, the cavity is assembled at UHV and “trampoline” mechanical performance is characterized. Due to the trampoline’s large Brownian motion, we apply radiation force feedback to damp the fundamental mode, which is sufficient to allow us to lock the cavity resonance to the laser frequency. Currently our measurements are limited by thermal intermodulation noise (TIN) in the system, and we will discuss our approaches to mitigate this; if successful, our system will provide access to measurement near the standard quantum limit and generation of broadband optomechanically squeezed light at room temperature. |
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SS01.00004: Analyzing superradiant emission by partially inverted atomic ensembles Aswath Suryanarayanan, Hanzhen Ma, Oriol Rubies-Bigorda, Susanne F Yelin Superradiance occurs in atomic ensembles due to an exchange of photonic excitations leading to constructive interference of emitted photons. The interacting, many-body nature of superradiance in an atomic ensemble causes the Hilbert space's dimensionality to scale exponentially, increasing the problem's analytical complexity. Previous models have attempted to simplify the system by working with size-constrained Dicke states or by considering only singly-excited states, or by using quantum jumps. However, these approaches are unable to reveal much about the superradiant burst or the late time dynamics of the ensemble. This research builds on the work of Ma et al. 2022, who use an integrated method with two probe atoms to obtain a non-linear two-atom master equation which captures the dynamics of the whole system. However, this model yields unphysical results for initially partially inverted ensembles among other issues. This research attempts to modify the aforementioned model to avoid apparent unphysical changes to the average upper state population and the cooperative decay rate. This is accomplished by both brute force - applying direct constraints and modifications to the cooperative decay rate - and analytic - improving theoretical approximations and imposing energy conservation - approaches. |
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SS01.00005: Graphene oxide: synthesis method and oxidation influence on the fluorescence characteristic times Jhon S Useche, J. J. Prias-Barragan, Gerardo Fonthal The effect of oxidation (Ox) on the characteristic fluorescence times (τ1, τ2) of graphene samples is presented here. Graphene Oxide (GO) samples were synthesized by pyrolysis method. The Ox of the samples was estimated from 9.4 to 16.6 %, employing EDS. The τ1 and τ2 were measured by TRPL. Results revealed linear behavior in the τ1(Ox) and τ2(Ox) and these were attributed to radiative processes with impurities and the radiative transitions from to states; respectively. These results suggest that pyrolytic GO are excellent candidate materials to applications, as fluorescence bio-markers. |
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SS01.00006: Revealing interface roughness and chemical composition distribution in III-V semiconductor quantum wells at the atomic scale Roy D Peña, Rosa E Diaz, Shuang Liang, Michael J Manfra Ternary III-V semiconductor quantum wells (QW) have shown to be interesting platforms to explore topological superconductivity. Their performance is greatly affected by the interface morphology, which in turn can be affected by growth parameters. Optimization of growth conditions and physical properties might be possible by using characterization techniques delivering structure and compositional information with atomic precision. Here, we applied a combination of high-resolution High-Angle Annular Dark Field imaging in the Aberration-Corrected Scanning Transmission Electron Microscope, together with advanced image processing and mathematical modeling using Python libraries to understand and quantify roughness and chemical composition distribution across these heterostructures interfaces. Our findings deliver metrology parameters to assess the quality of semiconductor heterostructure and highlight the relationship between such parameters and growth conditions. |
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SS01.00007: Controlled growth and transport property of Bi2Se3 and WSe2 thin film Ahamed Raihan, Jyotsna Das, Ravinder Kumar, Dereje Seifu In this work, we prepared a high-quality topological insulator (TI) and transition metal dichalcogenide (TMD) thin films by magnetron sputtering. Single-target sputtering and co-sputtering techniques are used to prepare these samples. Bi2Se3 and WSe2 were fabricated by radiofrequency magnetron sputtering at temperature T = 300K – 450K, and their properties were evaluated. Bi2Se3 (x) and WSe2 thin films with different compositions (x=5, 25, 50, 100, and 125) on sapphire were fabricated. For selenium (Se) deficiency, Se was co-sputtered with composite TI and TMD targets. Rapid temperature annealing was done to crystallize the film. The prepared thin film's XRD, XPS, and Raman measurements were conclusive. To perform the transport measurements millimeter size Hall-bar device is fabricated using a mask, not by using lithography and resist. The transport measurements have been done at different temperatures from T = 4 - 300K. For TI (Bi2Se3), the magnetoresistance is linear with the field. We reported finding high conductivity for Bi2Se3, which implies surface conductivity. For TMD (WSe2), we reported having semiconducting conductivity. |
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SS01.00008: Measuring Both Series and Parallel Impedances in the Quantum Hall Effect peter cameron The concept of impedance matching got lost in quantum mechanics. The quantized near-field interaction impedances of both photon and electron are not to be found in the physicists' curriculum, text books, or journals. What governs amplitude and phase of energy transmission in the fundamental photon-electron interaction of QED got lost in physics. There are two possibilities for quantum matching in the quantum Hall effect, either magnetic or electric coupling. The measured quantum Hall impedance is that of the ∼25812 ohm series configuration, the sum of magnetic and electric impedances, a factor of 1/2α larger than the ∼377 ohm photon far-field impedance. There exists the possibility that one might measure a quantum Hall impedance 1/2α smaller than the 377 ohm photon far-field impedance, measure the ∼5.498 ohm impedance of the parallel configuration, a range of interest in coupling condensed matter to electromechanical transducers, as for instance transistors to loudspeakers. One might also consider extending this approach to the fractional QHE. |
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SS01.00009: Disentangling Many-Body Effects in the Coherent Optical Response of 2D Semiconductors Chiara Trovatello, Florian Katsch, Qiuyang Li, Xiaoyang Zhu, Andreas Knorr, Giulio Cerullo, Stefano Dal Conte In monolayer transition metal dichalcogenides (1L-TMDs), the reduced Coulomb screening results in strongly bound excitons which dominate the linear and the nonlinear optical response. Despite the large number of studies, a clear understanding on how many-body and Coulomb correlation effects affect the excitonic resonances on a femtosecond time scale is still lacking. Here, we use ultrashort laser pulses to measure the transient optical response of 1L-WS2. From the pump-probe spectra we retrieve the absorption spectrum as a function of time using Kramers−Kronig constrained variational analysis within the thin-film model approximation. In order to disentangle many-body effects, we perform exciton lineshape analysis on the out-of-equilibrium absorption spectrum and we systematically study its dependence on pump photon energy and intensity [C. Trovatello et al., Nano Letters, 22, 5322–5329 (2022)]. |
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SS01.00010: Majorana-like Coulomb spectroscopy in the absence of zero-bias peaks Marco Valentini, Maksim Borovkov, Elsa Prada, Sara Martí-Sánchez, Marc Botifoll, Andrea Hofmann, Jordi Arbiol, Ramon Aguado, Pablo San-Jose, Georgios Katsaros Hybrid semiconductor–superconductor devices hold great promise for realizing topological quantum computing with Majorana zero modes . However, multiple claims of Majorana detection, based on either tunnelling or Coulomb blockade (CB) spectroscopy, remain disputed. Here we devise an experimental protocol that allows us to perform both types of measurement on the same hybrid island by adjusting its charging energy via tunable junctions to the normal leads. This method reduces ambiguities of Majorana detections by checking the consistency between CB spectroscopy and zero-bias peaks in non-blockaded transport. Specifically, we observe junction-dependent, even–odd modulated, single-electron CB peaks in InAs/ Al hybrid nanowires without concomitant low-bias peaks in tunnelling spectroscopy. We provide a theoretical interpretation of the experimental observations in terms of low-energy, longitudinally confined island states rather than overlapping Majorana modes. Our results highlight the importance of combined measurements on the same device for the identification of topological Majorana zero modes. |
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SS01.00011: Superconductivity of repulsive spinless fermions with sublattice potentials Yuchi He, Kang Yang, Jonas Hauck, Emil J Bergholtz, Dante M Kennes We explore unconventional superconductivity of repulsive spinless fermions on square and honey- |
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SS01.00012: MAGNETISM . |
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SS01.00013: Effect of disorder on thermodynamic instability of binary rare-earth - nickel - palladium compounds Prashant Singh, Del Rose Tyler, Yaroslav Mudryk The investigation of the intermetallic compounds, in particular those formed by the rare earth (R) elements, covers an important area of scientific research, with emphasis on the identification of new phases and their potential use in technological applications. We investigated the thermodynamic and electronic origins of phase instability in SmX2 and Sm10X21 (X=Ni, Pd) based rare-earth compounds using machine-learning trained analytical descriptor and first-principles density-functional theory. The convex hull construction illustrates why SmPd2 compound is unstable in the Sm-Pd binary system despite having more negative formation energy than experimentally observed SmNi2. The instability of disordered Sm(NixPd1-x)2 solid solution in MgCu2 Laves phase is triggered by Pd alloying that reduces the local charge correlation by charge screening effect, which also reduces the underlying Sm-Pd and Ni-Pd hybridization. This work emphasizes both the usefulness and limitations of machine-learned analytical descriptors for quick thermodynamic assessment of phase stabilities, while emphasizing the utility of advanced ab-initio methods for providing key quantum mechanical understanding of structural, thermodynamic, and electronic properties. Specifically, our study highlights peculiar features in band-structure responsible for thermodynamic instability, which can be useful to understand other chemically complex rare-earth compounds. |
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SS01.00014: Temperature influence in the magnetoresistance of graphene oxide films Jose D Gutierrez Londoño, J. J. Prias-Barragan Experimental measurement of temperature influence in the magnetoresistance (MR) of graphene oxide (GO) films, are presented here. GO films were synthesized by pyrolysis method. MR were measured employing a PPM system, with temperature varied from 100 to 400 K and the externally applied magnetic field were varied from 0 to 40 kOe. Positive, negative and reentrant MR were observed in the ranges of 200-300, 360-400 and 100, 330 K; respectively, possibly attributed to type of charge carrier involved on the electrical conduction. These results suggest GO films as an excellent candidate materials to spintronics. |
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SS01.00015: Effect of X-Ray Irradiation on Magnetocaloric Material, (MnNiSi)1-xFe2Gex John Peter J Nunez, Vaibhav Sharma, Jessika V Rojas, Radhika Barua, Ravi L Hadimani Magnetic refrigeration based on magnetocaloric effect (MCE) at room temperature is generally considered as a potential substitution for classical vapor compression systems due to its high efficiency and environmental friendliness. (MnNiSi)1−x(Fe2Ge)x composition (x=0.34) alloy was prepared by arc melting, crushed, and sieved to approximately <32 microns. They were utilized in examining the possible magnetic and structural changes when exposed to a dosage of a continuous sweeping rate of ~>120 Gy/min and an absorbed dose of 35 kGy of X-ray radiation. This study reports observable trends in magnetic measurements. Magnetization in the magnetization vs. temperature (both heating and cooling) measurements showed an increase from 2.72 emu/g to 4.01 emu/g in the irradiated sample. The magnetization vs. magnetic field loops exhibited irradiation-induced magnetic hysteresis. The irradiated sample also exhibited an observable change in its coercivity of ΔHc = 14.7% at 200 K. A maximum entropy change ΔSmag of ~ 11.139 J/kg*K and a Tave peak of 317.5 K was achieved for the pristine sample in comparison to ΔSmag of ~ 11.349 J/kg*K and a Tave peak of 312.5 K for the irradiated sample. These presented results provided deeper insights into tuning the magnetic and structural effects of irradiation in the (MnNiSi)1−x(Fe2Ge)x composition (x=0.34) that can be utilized in a wide range of magnetocaloric applications in high-energy radiation environments. |
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SS01.00016: Effects of geometry on antiferromagnetic textures: boundaries and geometric curvature Oleksandr V Pylypovskyi, Yelyzaveta Borysenko, Artem Tomilo, Denys Kononenko, Kostiantyn Yershov, Ulrich Roessler, Jürgen Fassbender, Jeroen van den Brink, Denis D Sheka, Denys Makarov Geometric curvature in nanowires and shells is established as a powerful method to tailor chiral and anisotropic responses in ferromagnets. Here, we apply the framework of curvilinear magnetism to antiferromagnetic (AFM) systems. First, we consider curvilinear AFM spin chains with the nearest-neighbor exchange and hard axis of anisotropy along the chain. Their shape is characterized by curvature κ and torsion τ. These functions determine the direction of the geometry-driven Dzyaloshinskii vector D and easy axis of anisotropy stemming from exchange. Furthermore, the broken translation symmetry in AFM chains arranged along space curves leads to the weakly ferromagnetic response proportional to κ and τ even if the magnetic texture is locally homogeneous. While the plane AFM chains possess the uniform ground state, the geometry-induced anisotropy axes and chiral response become pronounceable approaching spin-flop phase. Namely, in AFM rings the non-zero D leads to the appearance of canted state for the large enough κ, while spin-flop phase splits in two phases by the value of K with different topology of the order parameter. For 3D chiral AFMs, the sample boundaries alter the width and produce an additional twist of domain walls and skyrmions near the surface. |
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SS01.00017: YSZ Flexible ceramic magnetic bilayers for remote sensing in extreme conditions Debendra Timsina, zahir Islam, Shawn Pollard, Firouzeh Sabri Flexible YSZ ceramic sheets were evaluated as potential platforms for flexible spintronic devices. These were coated with (Ni80Fe20, Py) films of increasing thicknesses ranging from 10nm -100nm by means of DC magnetron sputtering. The stability and the integrity of the Py film was evaluated as a function of temperature cycles and induced stress/ strain between 1000C and -25C. Characterization techniques included FE-SEM, profilometry, and Kerr microscopy. Work presented will provide the framework for next generation remote sensing devices for extreme conditions. |
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SS01.00018: Artificial anti-gravity and Designing of UFOs Gh. Saleh As is well known, the flow of electrons or, in other words, the electric current can create magnetic fields in the solenoid. Magnetic fields can cause electrons to flow through solenoid and produce electric current too. If the electric current reaches a specific value, a magnetic field could be created. Indeed, the magnetic and electric fields have the homogeneity properties of energy. |
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SS01.00019: The Role of Stoichiometry in Mn1-xZnxFe2O4 Ferrite Microwave Absorbers Andrew S Padgett As 5G technology moves higher into the microwave frequency regime the risk of coupling EM energy into susceptible electronic circuits grows. Minimizing this interference is driving the need for compact, lightweight broadband absorbers to protect sensitive and high precision electronics. Manganese zinc ferrite (Mn1-xZnxFe2O4) microparticles have previously been demonstrated to be magnetically lossy up to 10 GHz, the desired frequency regime, and have the potential to meet the energy density and attenuation performance needs. However, optimizing the shielding effectiveness requires improved understanding of Mn1-xZnx stoichiometry and the dominant dielectric and magnetic absorption mechanisms for each stoichiometry. This presentation discusses results, up to 10 GHz, from experimentally investigating the shielding effectiveness and TE011 loss attenuation of Mn1-xZnxFe2O4 with a mean particle size of 30 microns, loaded to 50 volume percent in epoxy, and variation in x values from 0 to 1 in intervals of 0.1. Complex permeability and permittivity measurements were conducted to identify the peaks in the dielectric and magnetic loss tangents. An increase in absorption was observed in Mn1-xZnxFe2O4 for x=0.4, 0.5, 0.6, and 0.7 compared with other stoichiometries at 2 and 5 GHz TE011 modes, and we discuss possible explanations based on resonance behavior indicated by the dielectric and magnetic the loss tangents. |
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SS01.00020: Iron Based Soft Magnetic Nanofilms Deposited by Impacting Nanoparticles Rabindra R Khanal Wireless communication has been rapidly progressing toward the commercialization of 5G and the development of 6G. The frequency spectrum of 5G and 6G varies from a few hundred Megahertz to tens of Gigahertz. Increasing need for lighter, faster, and smarter devices in highly miniaturized packages, the integration of thin film soft magnetic cores with high saturation magnetization and uniaxial anisotropy on an electronic circuit is important. Nanocomposite soft magnetic films assembled by Fe/Fe3O4 core-shell nanoparticles may be the most suitable candidate for the desired high-frequency magnetic properties. It is crucial that the fabrication of such films must be compatible with Si-based integration, where a restricted processing temperature is required to incorporate the underlying integrated circuits. The high-temperature magnetic post-annealing is usually necessary to induce in-plane uniaxial anisotropy in these nanocomposite films, which is apparently incompatible with the Si-integrated designs for high-frequency applications. For materials vulnerable to high-temperature processes, the negatively charged nanoparticles can be accelerated by applying positive bias voltage onto the substrate held at different angles. As a result, the shapes of the deposited nanoparticles can be changed from original spheroids to a general ellipsoid, which is expected at room temperature to induce in-plane uniaxial anisotropy in the nanocomposites assembled by the Fe/Fe3O4 core-shell nanoparticles. |
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SS01.00021: STRONGLY CORRELATED SYSTEMS, INCLUDING QUANTUM FLUIDS AND SOLIDS | COMPLEX STRUCTURED MATERIALS, INCLUDING GRAPHENE . |
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SS01.00022: Variation of the properties of a fully spin-polarized two-dimensional electron gas that is separated from its neutralizing background Orion Ciftja In most of the cases, one studies a two-dimensional electron gas (2DEG) system by assuming that the electrons are immersed in a jellium neutralizing positive background. The standard approach is to view the system of electrons confined on the same layer as the 2D jellium background. This well-known model has been very useful to explain various properties and possible quantum phase transitions that occur in such a 2D system. The objective of this work is to study the properties of a fully spin-polarized 2DEG model in the thermodynamic limit with the modification that the 2D system of electrons is separated by an arbitrary distance from the neutralizing 2D layer. We use a Hartree-Fock (HF) approach and find that the separation of the 2D system of electrons from the 2D jellium background acts as an effective kinetic energy that increases the overall energy of the system. This effective increase of kinetic energy by the separation effect is more pronounced at high density values where electronic liquid states are energetically more favored compared to Wigner solid states. This leads us to believe that the effect observed would adversely affect the energetic stability of the liquid electronic states in such a way as to further enhance the Wigner crystallization process. |
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SS01.00023: Relationship between oxide coverage and optical response of graphene oxide structures Cristian González Tapiero, L. Diana Castañeda-Trujillo, J. J. Prias-Barragan Graphene oxide (GO) is a novel material that offers wide basic and applied perspectives in science. In this study, it is presented the theoretical characterizations of different GO structures (5%, 9%, 13%) via DFT computational calculations, elucidating IR, UV-Vis absorption spectra and electronic transitions in the HOMO-LUMO boundary orbitals that allow us to explain the relationship between the electron density distribution on GO surface and its reaction mechanisms with nucleophilic and electrophilic molecules. The theoretical parameters were compared with experimentally obtained results for pyrolytic GO. These results suggest that GO is an attractive material to optoelectronics of sensors and devices. |
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SS01.00024: 2D nanosheets of natural vermiculite clay - tuning the aptitude for exfoliation Barbara Pacakova, Bera Lachtingen-Dahl, Hanna Demchenko, Paulo Henrique Michels Brito, Steinar Raaen, Jon Otto Fossum
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SS01.00025: In Situ Measurements of Strain Evolution in Graphene/Boron Nitride and Transition Metal Dichalcogenide Heterostructures Using a Non-Destructive Raman Spectroscopy Approach YOOSUK KIM, Marc B Mezzacappa, Dheyaa Alameri, Brian Thomas, Chi-Hou Lei, Irma Kuljanishvili Strain engineering is a promising method to manipulate the electronic and optical properties of two-dimensional (2D) materials. In this study, non-destructive Raman spectroscopy was used to investigate the strain evolution of single-layer graphene (SLGr), few-layer boron nitride/graphene (FLBN/SLGr) heterostructures, and transition metal dichalcogenides (TMDs). The prepared 2D materials are synthesized via the chemical vapor deposition method and then transferred to a flexible polyethylene terephthalate substrate for strain measurement. For this study, a customized mechanical device-jig to be used as an insert for the 3D piezoelectric stage of the Raman system was designed and manufactured in-house. In situ investigation of the effects of applied strain in graphene detectable via Raman spectral data in characteristic bonds within SLGr and FLBN/SLGr heterostructures is carried out. SLG exhibited higher Raman shifts in the 2D band at the same strain range compared to the FLBN/SLGr heterostructure. Additionally, we used the same approach to investigate strain evolution in various TMDs and their heterostructures. This study presents an important pathway for designing 2D material heterostructures and flexible devices. |
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SS01.00026: Employing a novel approach for a controlled fabrication of 1D nanowires on suspended microstructures of arbitrary geometries using two direct-writing technologies Nicholas J Schaper, Irma Kuljanishvili, YOOSUK KIM, Keith X McCormack, Ivan I Kravchenko, David Gosztola, Maria Pantano, Nickolay Lavrik, Dale K Hensley Recent progresses in additive manufacturing have inspired new technologies, such as the direct laser writing technique based on two-photon polymerization (2PP), which complements and further enriches the nanofabrication tools portfolio. In this study, we combine 2PP and our mask-free scanning probe-assisted "direct-write patterning" method to allow for: a) the fabrication of micro-bridge structures with the sub-micrometer resolution, b) selective synthesis of crystalline ZnO nanowires at predefined locations, respectively. This synergistic approach enables cantilever probe patterning of catalysts directly on suspended micro-bridges for CVD growth of nanoscale material in a templated manner. This work represents the first proof-of-concept experiment demonstrating a versatile and scalable methodology. Our method is adaptable and simply scalable to grow a variety of other nanomaterials in a controlled and selective manner on size-independent micro/nanoscale structures. The possibility of integrating this new approach with conventional lithography techniques provides a step forward to developing a novel class of hybrid polymer-silicon-1D or -2D materials and systems. The quality of the ZnO nanowire assemblies was assessed using several physical characterization methods. |
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SS01.00027: Comparison between blue methylene adsorption in graphene oxide and activated carbon Laura V Gutierrez López, J. J. Prias-Barragan This work presents the comparison between blue methylene adsorption in Graphene oxide (GO) and activated carbon (AC), employing UV-Vis spectroscopy technique. GO samples were synthesized by using pyrolysis method. The GO samples were activated by chemical and physical methods, employing NaOH agent and laser induced graphene (LIG) system. Results at 72, 81, 83 and 88 % of adsorption in GO-without activation, AC-NaOH, GO-LIG and GO-NaOH as filaments; respectively, revealed that GO-NaOH samples, exhibits more adsorption, possibly attributed to high surface area, as expected. These results suggest that GO-NaOH are excellent candidate material to filters. |
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SS01.00028: Exciton Modulation Through Laser Elucidation in Two Dimensional MoS2 Anthony Trofe, Sajedeh Pourianejad, Kirby b Schmidt, Tetyana Ignatova Modification of two-dimensional transition metal dichalcogenide enables a wide variety of electric and optical applications; however, this often results in introduction of undesirable properties. Current methods for defect modification include the use of chemical doping and ion bombardment. One possible solution lies in the use of laser radiation for controlled and precise property alteration. As prepared 2D MoS2 is initially p-doped with laser irradiation while continued elucidation results in photocleaning. Changes are best characterized using the photoluminescent behavior - specifically the A and B exciton – in additional to E2g and A1g Raman peaks. To determine the extent that MoS2 is modified, we analyzed the spectra of Confocal Raman, photoluminescence, and determined carrier concentration using the Mass Action model and experimentally confirmed with Kelvin Probe Force Microscopy. The critical point where doping begins to lead to a reduction in sample quality is further analyzed. |
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SS01.00029: The effect of linearly polarized dressing field on the titled electronic states in 1T'-MoS2 Godfrey Gumbs, Andrii Iurov, Liubov Zhemchuzhna, Danhong Huang, Kathy Blaise, Chinedu Ejiogu By applying the so-called Floquet engineering, we have done a detailed investigation and built a rigorous formalism for the electronic states of 1T'-MoS2 in the presence of a linaarly polarized dressing field in the off-resonance regime. Our work includes both obtaining closed-form analytical expressions for the energy dispersions of the obtained dress states in some specific cases, such as an absence of the band gap for an initially non-irradiated material, and a thorough numerical investigation for all the other cases of the spin- and valley-polarized electronic band structure of 1T'-MoS2. We have found that the effect of linearly polarized light on 1T'-MoS2 is drastically different compared to that for any other known Dirac cone materials since the energy band gaps are also greatly modified by this type of dressing field. |
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SS01.00030: Differential entropy per particle as a probe of van Hove singularities and flat bands Dmytro Oriekhov, Yelizaveta Kulynych We derive the general expressions for the differential entropy per particle near van Hove singularities (vHs) in the density of states. The dependence of entropy per particle on chemical potential and temperature demonstrates different behavior depending on the type of vHs, and distinguishes high-order vHs with different divergence exponents and flat bands. In addition, it allows one to test the "flatness" of the band in experiment. We compare the analytic predictions with the numerical calculation of the differential entropy for tight-binding models of graphene, the Lieb lattice, and the square-octagon lattice. Our results show that the obtained analytic expressions capture the main features of the differential entropy, thus serving as a good probe for details of the density of states structure. |
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SS01.00031: SURFACES, INTERFACES, AND THIN FILMS | NONEQUILIBRIUM QUANTUM PHYSICS | GENERAL THEORY, COMPUTATIONAL PHYSICS | QUANTUM INFORMATION, CONCEPTS, AND COMPUTATION . |
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SS01.00032: Observation and analysis of the spectrum of electrons emitted following the Auger decay of hot holes in the valence band of Si V. A. Chirayath, Jack Driscoll, Alexander Fairchild, Sima Lotfimarangloo, V Callewaert, Bernardo Barbiellini, Randall Gladen, Brooke C Wallace, Ali R Koymen, Alex H Weiss The Auger decay of a hot hole in the valence band of Si can result in the emission of an electron from the surface due to its wide valence band (~ 12 eV). The energy spectra and the intensity of electrons resulting from such Auger transitions (termed VVV) may provide a way to investigate the Auger recombination processes in Si valence band. Traditional photon-based or electron-based Auger electron spectroscopies have limited ability to measure the spectra of the low energy VVV Auger electrons due to the obscuring presence of large probe-induced secondary electron background. Here, we present the spectrum of VVV Auger electrons emitted from Si without any probe induced secondary background. This is made possible by the application of positron annihilation induced Auger electron spectroscopy (PAES) where the Auger initiating valence hole is created via annihilation. PAES, therefore, allows the characterization of sample surfaces with positron energies (~1.25eV) much lower than the minimum energy required for secondary electron emission. We will discuss the theoretical analysis of the shape of the Si VVV Auger electron spectrum and estimate the efficiency of Auger recombination of the hot holes in Si. |
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SS01.00033: Estimating variations in surface chemical composition through the analysis of the high momentum region of the Doppler broadened annihilation gamma spectra V. A. Chirayath, Brooke C Wallace, Sima Lotfimarangloo, Jack Driscoll, Randall Gladen, Alexander Fairchild, Philip A Sterne, Ali R Koymen, Alex H Weiss Doppler broadened annihilation gamma spectrum (DBGS) measured after depositing low energy positrons on bilayer graphene on polycrystalline copper is compared to the spectrum obtained from the same sample surface but after the partial removal of the bilayer graphene film. DBGS from the partially sputtered surface shows a measurable change from the spectrum collected from the non-sputtered surface. We show that the observed variations in the annihilation gamma line shape can be used to quantify the surface chemical composition variation brought about by partial sputtering. The composition variation obtained from Doppler broadening spectroscopy was comparable to the changes observed in the intensity of the copper Auger peaks seen in the positron annihilation-induced Auger electron spectra (PAES). The results show the sensitivity and surface selectivity of the Doppler broadened annihilation gamma spectroscopy in obtaining the surface chemical composition. Our results provide impetus to the development of a new technique based on Doppler broadened annihilation gamma spectroscopy for probing the hidden or inaccessible surfaces of technologically important porous materials. |
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SS01.00034: A Transparent Hard Coating with Tunable Refractive Index David R Winn We demonstrate a novel method to completely anodize metal films applied to insulators, so that no metal remains and is transparent, except for an arbitrarily small connection line at an edge of the work piece. Normally the anodization results in an opaque metal barrier layer. The transparent anodization results in a hard metal-oxide film with ordered nanoporosity, up to 70% porous in hexagonal close packing, with pore diameters < 30 nm, pore lengths ~200x diameters (thickness ~several optical l). The formation of arrays of high aspect ratio nanopores under anodic oxidation of pure aluminium is a well-known phenomenon. Edge Anodization utilized a controlled immersion of a workpiece into an anodization bath, controlling current density and speed of immersion. Films of Al ~1-5 µm thick anodized to transparent Al2O3 resulted in uniform pores with diameter ~10–30 nm and density 8-9 × 1010 pores cm−2. The pores are far smaller than visible wavelengths and resultant heterogenous films are considered uniform for the optical properties of visible light with index of refraction n ~ f np + (1-f) no, where f is the porous fraction of the film, np is the pore index, equal to that of air (i.e. np = 1) unless filled, and no is the oxide matrix index. For the form of Aluminum Oxide here (boehmite, γ-alumina), for example, np ~1.6, and so for f = 60% porosity, easily achieved, the index of the film n~ 1.1, and for f = 40%, n~ 1.4, low enough to capture more light in fibers with such a cladding. At n=1.1 and core index n=1.6, ~47% of light is transmitted. |
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SS01.00035: Non-monotonic von Neumann entropy in open systems. A conjecture. Robert Englman In open, thermalizing systems, being in a non equilibrium situation, the von Neumann, or information theoretic Shannon entropy (Sinfo= -Tr
ho ln
ho) is not identifiable with the Clausius thermodynamic entropy S . Unlike the latter, it is capable of exhibiting a temporal maximum before reaching the final Gibbsian state. The necessary and sufficient conditions for this to happen are conjectured, and verified in numerous multi-state instances but not actually proven. They are written in terms of three energies: (1) Ein, the average energy of the states weighted by the initial occupation probabilities; (2) Edem, the mean energy of the states weighted equally, democratically; (3) Etherm, the energy average weighted by the final, fully thermalized, Gibbsian distribution. They read: Ein < Edem < Etherm. |
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SS01.00036: Effective mass concept for few-body nuclear systems Igor Filikhine, Abdwnnaceur Karoui, Courtney J Martin, Branislav Vlahovic We consider the possibility of utilizing the effective mass concept initially proposed in many-body and solid-state physics to study nuclear systems like 3N and 3alpha-cluster systems. Our consideration is based on a property of a three-body nuclear Hamiltonian for bound states. We describe the property as mass-energy compensation (MEC). The MEC reflects the general physical relation between mass and energy. For bound nuclear states, this relation appears as the mass defect formula. Recently, we investigated the mass-energy compensation for the three-nucleon Hamiltonian in relation to the three-body force acting in 3N systems. To avoid a sophisticated constrict for three-body force, we propose a phenomenological model in which the nucleon effective mass is defined so that to compensate the effect of the three-body force [1]. Another nuclear system constituted of identical particles is the system of three alpha particles (the cluster model for the 12C nucleus). The initial phenomenological model includes pair and three-body potentials. However, instead of using a three-body potential, we adjust the mass of the alpha particle in the system and define the alpha-particle effective mass that reproduces experimental data. The MEC property of the 3alpha Hamiltonian justifies the procedure. The MEC effect is modeled numerically and explained in the presented work. The effective masses of alpha particles for the 3alpha 0+ ground and excited states are evaluated. The coupling of these levels is shown. |
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SS01.00037: Non-Abelian Anyon Statistics in Rydberg Atoms Nora M Bauer, Elias Kokkas, George Siopsis We study the emergence of topological matter in two-dimensional systems of neutral Rydberg atoms in Ruby lattices. While abelian anyons have been predicted in such systems, non-abelian anyons, which would form a substrate for quantum computing, have not been generated. To generate anyons with non-abelian braiding statistics, we create punctures in the system with mixed e and m-condensed (smooth and rough) boundaries. 2-puncture states have a fourfold ground state degeneracy, based on the type of anyon enclosed; they can be trivial, e-enclosing, m-enclosing, or fermion-enclosing. We create superposition states of 2 punctures each containing e and m anyons, which can reproduce the Ising fusion matrix. Additionally, a 4-puncture state comprised of 2 superposition states allows braiding operations that implement the X gate. We confirm the presence of mixed boundary punctures as well as the emergence of these ground states numerically using the infinite DMRG technique. |
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SS01.00038: Design and Architecture of Large-scale Quantum Circuits Renuka Rajapakse, Christopher Stynar Designing large-scale quantum circuits is a cumbersome engineering task. Some of this difficulty is a result of the fundamentally complex nature of quantum computing, there are certainly aspects of the engineering task which can be handled by classical computers. One such example is qubit allocation. We show how some of these tasks can be automated using software development kits, and create quantum programs that can be tested on on prototype quantum devices. |
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SS01.00039: Interplay of embedding and chip connectivity in quantum annealing Tobias Kempe, Mohammad H Ansari, Ali S Tabei The feasibility of combinatorial optimization problems to be solved on quantum annealers strongly depends on the ability to represent their problem graph on the physical chip architecture. Especially the connectivity between qubits proves to be of crucial importance in addition to the number of qubits itself. This is due to the reduced need of long, error-prone qubit chain encoding when the connectivity can be mapped directly. However, more than needed physical connectivity can introduce additional noise and thereby logical errors. We examine the tradeoff between those opposing effects and deduce a model of suitability of chip architectures for certain kinds of problems graphs. For evaluation, we focus on the success probability of respective solving attempts. |
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SS01.00040: Two-tone spectroscopy to characterize losses due to two-level systems Ivan Nekrashevich, Bianca Giaccone, Alexandr Netepenko, Roman Pilipenko, Alexander Romanenko, Anna Grassellino It was shown that two-level system (TLS) defects are among the main sources of loss and decoherence in superconducting quantum devices. Microscopic nature of TLSs is still an open question and it is important to develop experimental techniques that allow to gather detailed information about them and characterize various materials beyond just the magnitude of the loss tangent. This knowledge will help to distinguish between various defects and loss mechanisms associated with them, and develop material processing and preparation procedures to improve coherence times of quantum computing devices. |
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SS01.00041: ENERGY RESEARCH AND APPLICATIONS | MEDICAL PHYSICS . |
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SS01.00042: Revisiting the Electrochemical Reduction of CO2 on Au25(SR)-18 Nanocluster Dominic Alfonso Previous experimental breakthrough reveals the potential to create novel heterogeneous catalysts for electroreduction of CO2 to a high-value product CO using ligand protected Au-based nanoclusters. Since the chemical composition and geometric structures are precisely defined, it is possible to adopt robust design guidelines for the development of practical catalysts and to fundamentally elucidate the underlying reaction mechanism. In this work, the mechanistic aspect of CO2 reduction reaction (CO2RR) and hydrogen evolution reaction (HER) on the ligand protected nanocluster was revisited using DFT. Previous theoretical efforts are mainly based on thermodynamic viewpoint. Here, I report the first study that included activation barrier of each elementary step. The potential-dependent reaction and activation free energies were determined by combining Chan-Nørskov capacitor model and the computational hydrogen electrode (CHE) model. The study was able to furnish a much more nuanced view into the multi-step electrocatalytic reactions. From the reassessment of the ability of the nanocluster to release a -SR and -R ligand, it was found that while dealkylation is more thermodynamically feasible, the high calculated barrier indicates that the exposure of S active site is kinetically hindered. In contrast, dethiolation is predicted to be nearly barrierless, suggesting that Au site generation is more favorable in agreement with the experimental observation. From the calculated free energy barriers, CO2RR on the Au site is predicted to be more active and selective than on the S site, supporting the experimentally observed performance of the dethiolated nanocluster. |
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SS01.00043: Ionic Transport in V2O5 from First Principles Gavin Holbrook Gavin Holbrook, Sakthi Kasthurirengan, and Hartwin Peelaers |
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SS01.00044: Two years after Covid-19 first hit, the city that never sleeps is back to waking up early Christoph J Meinrenken, Patricia J Culligan We used the previously published MFRED dataset, which tracks real and reactive power in 390 apartments in Manhattan. |
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SS01.00045: Pseudohalide Enhanced Optical Response and Stability of Perovskites for White Lighting-Emitting Diodes Saroj Thapa, Peifen Zhu Lead-halide perovskite nanocrystals (NCs) exhibit a better color gamut compared with conventional lighting sources, and comparatively cheaper production costs which may offer an upcoming substitute for future color-converting white lighting devices. However, these NC suffer from poor stability and are highly moisture sensitive that which must be overcome for the successful commercialization of perovskite-based technologies. Herein, we demonstrated the highly luminescent and stable perovskite NCs via the addition of pseudohalide compounds. The new pseudohalide composites gained their photoluminescence quantum yield almost 30% greater than that of parent NCs retaining its initial luminescence properties almost by 90% over a time of 5 months of storage time. White light-emitting diodes based on pseudohalide composites have been fabricated and it shows the excellent color quality and high luminous efficacy. |
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SS01.00046: Prediction of normal tissue complication probability and equivalent uniform dose of organs at risk in lung cancer treatment plans using an Artificial Neural Network Mukunda P Pudasaini, Theodora Leventouri, Silvia Pella, Wazir Muhammad The purpose is to predict Normal Tissue Complication Probability (NTCP) and Equivalent Uniform Dose (EUD) in external beam radiation therapy of lung cancer treatment plans by applying an Artificial Neural Network (ANN). 100 lung cancer treatment plans of anonymized patients were selected. NTCP of Organs At Risk (OARs) and EUD were calculated for all plans using an analytical EUD-based linear quadratic model. The calculated EUD model-based NTCP and EUD were used as outputs for training and testing. The inputs for the ANN model were treatment modality, location of tumor, prescribed dose, fractions, planning target volume (PTV), number of fields, mean dose to PTV, gender, age, and mean doses to the OARs. All numeric data were normalized in the range of 0 to 1, while categorical inputs were changed to 0 or 1. Our ANN is based on Levenberg-Marquardt back-propagation algorithm with one hidden layer having 16 nodes with 13 inputs and 2 outputs. 70% of the data were employed for training, 15% for validation, and 15% for testing. The ANN performance was evaluated by mean squared error (MSE) and correlation coefficients (R) of regression. In NTCP and EUD prediction, the average correlation coefficients are 0.94 for training, 0.89 for validation, and 0.84 for testing. The maximum ANN mean squared error (MSE) is 0.025 in predicting NTCP and EUD of the heart. These results indicate that our ANN can be employed to predict NTCP and EUD. |
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SS01.00047: Magnetic susceptibility measurements from magnetic resonance imaging (MRI) Fredy R Zypman, Roman Fleysher, Yonathan Magendzo Detection of traces of iron in the brain is useful for early diagnosis, progression and treatment monitoring of various neurologic and psychiatric diseases. Iron and, in general, different tissues possessing different magnetic susceptibilities expose themselves via small spatial variations of the magnetic field during Magnetic Resonance Imaging (MRI). Data acquisition and image analysis methods that visualize spatial distributions of magnetic susceptibilities are known as Quantitative Susceptibility Mapping. However, most modern techniques model the brain as a collection of magnetic dipoles and because only the longitudinal component of magnetic field is assessable to MRI, the resultant problem is ill posed. To address this, we are developing a new tissue model and algorithm to map susceptibility from the experimentally measured magnetic field in the whole region. Our algorithm addresses this problem by first solving the forward magnetostatics problem of the sample inside the coils for a trial susceptibility map. Second, this solution is used to compare the theoretical longitudinal field component with the experimental one. Third, the susceptibility map is varied until the difference between the numerical and experimental field components is minimized. |
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SS01.00048: PHYSICS EDUCATION | PHYSICS OUTREACH AND ENGAGING THE PUBLIC | HISTORY OF PHYSICS | EARLY CAREER SCIENTISTS | GENERAL PHYSICS . |
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SS01.00049: A Skateboarding Experiential Learning Activity for Introductory Physics Liang Zeng, Guang Zeng Instructors of introductory college physics courses are in a unique position to explain the physics of skateboarding and its associated risks. A field trip to a skate park to explore the law of conservation of energy and measure the impact forces can enhance student analytical thinking skills and their appreciation of physics in everyday life. Through the measurement of the impact forces and student discussions of their own skateboarding experiences, students are better prepared to protect themselves from skateboarding-related physical injuries. |
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SS01.00050: Neurodivergent Fields: A Study on Critical Disability Physics Identity Development of Neurodivergent Nonacademic Physicists Liam G McDermott
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SS01.00051: Women Supporting Women in the Sciences: Low-cost laboratory kits utilized in primary- and secondary-level classrooms in eastern Africa via local partners Jill K Wenderott, Joyce Elisadiki, Cecilia China, Julie Fornaciari, Danielle Butts, Gloriana Monko, Sossina Haile Improving the number of women choosing science, technology, engineering, and mathematics (STEM)-related subjects in higher education is a complex and multi-faceted challenge. One strategy to improve representation on which Women Supporting Women in the Sciences (WS2),1 a global initiative funded by a 2020 APS Innovation Fund, has recently focused has been the development and deployment of low-cost physics and materials science laboratory kits to promote primary- and secondary-level (K-12) girls' interests in STEM. To date, these laboratory kits that utilize easy-to-find, local resources and cover topics from light and color to food science to electrostatics have been used by over 1400 students, predominantly in eastern Africa, with about 70% being girls.2 Successful delivery and teaching of these laboratory kits have been accomplished by working with WS2 Partners and their local communities. This talk will discuss the lab kit design and distribution phases, as well as outcomes to date from the use of these lab kits in classrooms across eastern Africa. |
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SS01.00052: Transcendence of the Militarization of Physics: Establishing the World's First Department of the Foundations of Physics Kathleen V Tatem Lingering historic military influences in physics and the academy resurface in modern conflicts in Hawai'i over telescope planning. With the paradigm of modern physics rooted in a Cold War military intervention, I draw upon the philosophy of Thomas Kuhn to advocate for respecting indigenous land rights and for the professionalization of research in the foundations of physics to establish cross-cultural scientific dialogues and genuine inclusion of underrepresented people in physics. First conceptualized in 2012 at Columbia University, I outline an interdisciplinary research strategy in the foundations of physics that aims to take responsibility for the impacts of the Manhattan Project on physics itself. Based on patterns and insights in experimental physics and astronomy instrumentation, I show that the high middle ground demands of the Mauna Kea Movement, which cannot be met with astronomy instrumentation or optics, are aligned with my meditations on how to transcend the militarization of physics: that my interdisciplinary research is the path to the end of the era of the telescope as a research tool. Lastly, I introduce Tatem Research Institute, established in 2022 to prioritize research in the foundations of physics and diversify this field. Envisioned as the world's first Department of the Foundations of Physics, Tatem Research Institute aims to facilitate an economic shift of scientific priorities to investigate experimental physics hypotheses generated from research in foundational questions. |
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SS01.00053: 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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SS01.00054: Deep learning guided estimation of laser sintered ceramic’s microstructure based on in-situ surface thermal emission signals jianan tang In laser processing, online estimation of microstructures is useful to ensure that desired properties are obtained. Currently, microstructures are usually characterized offline using scanning electron microscopes (SEM), which are labor, time, and cost-consuming. Here, we demonstrate a deep learning-based computational method to simulate micrographs, which resemble real SEM images containing important microstructure features, from the in-situ captured thermal emission strength. Experimental results reveal a strong correlation between the thermal emission brightness and the corresponding microstructure. A conditional generative adversarial network (CGAN) is trained to model this correlation. To obtain the best accuracy, a toy dataset consisting of artificial microstructures is established to investigate the effects of the network’s hyperparameters on performance. Then, the optimized network is trained on a real SEM image dataset and its accuracy is quantitatively evaluated using average grain size as the metric. The CGAN-generated microstructure images were found to be in good agreement, less than 5% in difference in average grain size, with the real SEM images. And the inference time is less than 1 second per image. This fast CGAN-based microstructure estimation method can potentially be used for process control and quality assurance in the laser sintering of ceramics to accelerate material development and improve productivity. |
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SS01.00055: Energy flow in laser-excited hBN-graphene heterostructures Tobias Zier, Arne Ungeheuer, Arne Senftleben, David A Strubbe Inter-material correlations of electrons and phonons in vdW heterostructures, like hBN-graphene open interaction and energy diffusion channels that are not present in either of the single materials. Recent research showed, e.g., out-of-plane heat transfer by electron-hyperbolic phonon coupling [1] or ultrafast relaxation of hot phonons [2]. Here, we studied how laser-deposited energy is distributed within and between the layers of the heterostructure. Therefore, we performed ab initio calculations of mono-layer hBN-graphene and many-layer hBN-graphite heterostructures excited by femtosecond-laser pulses with a central wavelength of 800 nm. Note that hBN is transparent for that wavelength: it does not absorb laser-pulse energy, whereas graphene does. By comparing our simulation results to our experimentally obtained time-resolved electron diffraction data we gain insights on the energy flow from excited graphene to the connected hBN layer within a 2D heterostructure on an atomistic level and ultrashort timescale. |
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SS01.00056: Complexity-Size and Complexity Rate-Size Rules in Stellar Evolution Georgi Georgiev, Travis Butler An open question is how complex systems self-organize to produce emergent structures and properties. We explore the quantity-quality transition in natural systems. This is to say that the properties of a system depend on its size. More recently, this has been termed the complexity-size rule, which means that to increase their size, systems must increase their complexity, and that to increase their complexity they must grow in size. We apply the complexity-size rule to stars to compare them with other complex systems in order to find universal patterns of self-organization independent of the substrate. As a measure of complexity of a star, we are using the degree of grouping of nucleons into atoms, which reduces nucleon entropy, increases the variety of elements, and changes the structure of the star. As a measure of the rate of self-organization and increase in complexity, we are using the average rate of nucleosynthesis over the lifetime of stars as a function of their mass. Here we find that, as for the other systems studied, the complexity of stars and the rates of increase of complexity are in a power law proportionality with their size. The bigger a system is, the higher its level of complexity is and the faster the rate of its increase - despite differing explosion energies and initial metallicities from simulations and data, which confirms the Complexity-Size and Complexity Rate-Size rules and our model. The complexity and the rate of increase of complexity of a star are also in a power-law relation with each other. |
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SS01.00057: The Uniform Acceleration of Falling Objects Depends on Rock the Psychologist's Work on Induced Motion and Induced Rest Douglas M Snyder Galileo’s principle has no explanation on its own. Instead, it finds its explanation in Einstein’s principle of equivalence. The principle of equivalence depends on Rock the psychologist’s theoretical and experimental work on induced motion and induced rest. The principle of equivalence depends on perceptual and cognitive factors investigated by Rock and others, all of which have not been seriously considered by physicists. The general theory of relativity which relies on the principle of equivalence, and indeed the special theory of relativity, depend on these perceptual and cognitive factors and on the relativity of an observer seeing himself at rest or instead in motion. The principle of equivalence does not work without an accelerating human observer who sees himself at rest in an inertial reference frame in a gravitational field. Einstein accomplished this through an extension of induced self-rest for a human observer moving at constant velocity to the accelerating observer through the accelerating observer’s interpretation of his physical environment. Relying on a particular arrangement of physical objects as opposed to other different arrangements of physical objects does not account for the presence or absence of gravity. The accelerating human observer’s interpretation of a specific arrangement of objects that includes his seeing himself at rest can account for the presence or absence of gravity. |
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SS01.00058: Investigation of structural, magnetic, and weak anti-localization properties of Bi2Se3 topological insulator (TI) doped with magnetic (Mn) and non-magnetic (In) elements NILADRI S KANDER, Suman Guchhait, Sajib Biswas, Amal K Das The present study explores the effect of magnetic (Mn) and non-magnetic (In) doping on structural, magnetic, and weak anti-localization properties of Bi2Se3 topological insulator (TI). The un-doped as well as Mn, In-doped Bi2Se3 are synthesized using a solid-state reaction method. The X-ray diffraction (XRD) along with Rietveld refinement reveals that, both Mn and In-dopants substitute the Bi-ion along with slightly interstitially incorporate in host Bi2Se3. It is also found that Bi-substitution is a little preferable for In-doping than Mn. The magnetic measurement represents diamagnetism of un-doped Bi2Se3 and ferromagnetism/ paramagnetism for Mn-doping, whereas In-doped Bi2Se3 shows a mixing of diamagnetism and Pauli paramagnetism. Electrical-transport establishes that In-doped Bi2Se3 preserves the host`s metallic nature; however, the arrest of metallic response is observed through the evidence of Kondo effect below 185K for high Mn-doping. More interestingly, the magneto-transport establishes that Mn-doping creates a prominent deviation in quantum weak anti-localization (WAL) feature of host Bi2Se3, whereas, In-doping shows a minor deviation in WAL effect for higher doping percentage. |
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SS01.00059: Tuesday Poster Miscellaneous I . |
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SS01.00060: Structural, thermal and electronic properties of two-dimensional amorphous graphene, silicene and silicon carbide Emel Gurbuz, Biplab Sanyal In recent times, low dimensional crystalline structures and van-der Waals (vdW) solids have attracted a lot of attention for their huge potential in device applications. However, the exploration of amorphous forms in two-dimension for property tuning is not so commonly found. Here, we present a detailed structural, electronic and thermal analysis of two-dimensional (2D) amorphous graphene(A-Gra), silicene(A-Si) and silicon carbide(A-SiC) by using Classical Molecular Dynamics (CMD) simulations for structure generation, stability tests, thermal conductivity and vibrational analysis while we use first-principles density functional theory (DFT) calculations for electronic structure and charge distributions. A comparison between the structures obtained from large-scale CMD and smaller scale DFT has been made. We find that A-Gra is planar and metallic with a thermal conductivity around 55.30 W/Km. A bilayer of A-Gra shows a vdW character without any chemical bond. On the contrary, A-Si prefers to create covalent bonds in a bilayer structure. It is found that the monolayer A-Si has a much lower thermal conductivity (2.68 W/Km) than A-Gra. Finally, we show that 2D amorphous silicon carbide can be stabilized not only as a single layer but also as a bilayer, where the chemical bonding between Si atoms exist only. Among our studied materials, A-SiC's thermal conductivity is found to be the highest (70.29 W/Km). Our vibrational analysis shows that the heat carriers in A-Si and A-SiC are extendons, especially diffusions in absence of localized vibrational modes. Finally, an observation of uneven charge distributions around the ring structures in these amorphous materials can serve as an interesting ingredient in designing future electronic devices by tuning the local functionalities. |
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SS01.00061: Extended Discharge Voltage Investigation on Solution-processed Low-cost wide band gap Li4Ti5O12 Anode and its Full-cell Application with V2O5 Cathode in Rechargeable Lithium-ion Battery under Low Polarization Potential Limit Tejveer S Anand, Aashish Joshi, Raghvendra Gupta, Henam Sylvia Devi, Amit Gupta, Madhusudan Singh Certain transition metal oxides-based electrode materials for Li-ion batteries (LIBs) have attracted importance due to their low cost, thermal stability, and high specific energy. In this work, sheet-like Li4Ti5O12 (LTO) with a calculated band gap of ~3.95 eV and V2O5 [1] was synthesized via a solution and green approach process. The electrochemical performance of the LTO anode was studied in detail by widening its potential window. The obtained LTO suffers high polarization and intercalation plateau loss when the discharge potential limit is set below 0.5 V. In addition lowering the discharge potential leads to a considerable increase in the specific discharge capacity: 195.56 mAh/g and 241.45 mAh/g at 0.1 C-rate for 0.5 V and 0 V, respectively. Regardless of high initial capacity, it limits its potential use over long-term cycling due to severe capacity fading, primarily due to the intercalation of lithium ions in the vacant sites of the Li7Ti5O12 after crossing the 1 V, which further leads to the formation of Li9Ti5O12, creating hindrance and less diffusive pathways for the subsequent lithium ions. Similarly, the cell shows excellent capacity retention of 86.37% after 250 cycles under the potential window of 1-2.5 V and also suffers less plateau loss even at high C-rates (>1 C). The V2O5 cathode cell exhibits an initial discharge capacity of 143.94 mAh/g at 0.1 C-rate between 2.5-4 V but suffers high polarization and curve distortion at high scan rates (>0.2 mV/s) in the CV test. Moreover, Li4Ti5O12||V2O5 full-cell assembly was carried out with the as-synthesized anode and cathode after successfully restricted electrochemical lithiation of V2O5 to 2.5 V. The full cell delivers an initial discharge capacity of 126.62 mAh/g at 0.12 C-rate with an energy density of 221.59 Wh/Kg. The above work indicates the potential use of LTO-V2O5 full-cell for high-power applications such as electric vehicles (EV). In addition, various ex-situ characterization (post cycling): XPS, TOF-SIMS, XRD, Raman, AFM, and FTIR, etc., were carried out to study electrode surface morphology and its interaction with electrolyte for SEI layer formation. |
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SS01.00062: Magnetic and magnetocaloric properties of iron nanoparticle and iron thin films embedded or sandwiched between titanium nitride thin films Kaushik Sarkar, Abiodun Odusanya, Manosi Roy, Jacob Som, Vanessa Jones, Abebe B Kebede, Steve Kriske, Frank W Wise, Dhananjay Kumar We have studied the magnetocaloric effect (MCE) in iron (Fe) nanoparticles embedded in titanium nitride thin film matrix in a multilayer structure and Fe thin films sandwiched between titanium nitride thin films. The total volume of Fe is kept same in both structures. This study has allowed a better understanding of the effect of dimensionality on the MCE in simple metallic systems assuming Fe particles to behave as zero-dimensional and Fe thin films as two-dimensional geometries. Fe nanoparticles of different sizes were embedded in a titanium nitride thin film matrix by varying the number of laser pulses during pulsed laser deposition (PLD). Similarly, Fe thin films were sandwiched between two layer of TiN films using PLD. Isomagnetic magnetization (M) versus temperature (T) measurements carried on nano particulate structures have shown the absence of any separation between zero field cooled (ZFC) and field cooled (FC) MT curves above the blocking temperature suggesting a negligible thermal hysteresis loss in the samples. Quantitative information about the isothermal entropy change (ΔS) in the Fe-TiN heterostructure system has been obtained by applying Maxwell relation to the FC MT data at various fields. The Fe-TiN heterostructure systems show a sizable ΔS over a broad range of temperatures (TB < T < 300 K). With the dynamic magnetic hysteresis absent above the blocking temperature, the negative ΔS as high as 1.6×103 J/Km3 is obtained for 0.2 T at 300 K. Finally, we report that Fe nanoparticle samples exhibit higher refrigerant capacity (RC) in comparison to Fe thin film multilayer sample and the RC increases with decreasing Fe particle size. The high RC value in Fe-TiN nanoparticle heterostructure is brought about by the weak temperature dependence of the isothermal entropy change. The broad range of usable entropy change and easy accessibility makes the Fe-TiN system interesting for next-generation solid-state cooling. |
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