Bulletin of the American Physical Society
APS March Meeting 2019
Volume 64, Number 2
Monday–Friday, March 4–8, 2019; Boston, Massachusetts
Session G70: Poster Session I (2:00pm5:00pm)Poster Undergraduate

Hide Abstracts 
Room: BCEC Exhibit Hall 

G70.00001: UNDERGRADUATE RESEARCH


G70.00002: Machine Learning Applied to MultElectron Events in Scintillator Harrison LaBollita, Morten HjorthJensen, Sean Liddick Conversion electron spectroscopy is a viable tool when studying the nuclear phenomenon, shape coexistence. When a neutronrich nucleus beta decays, a neutron transforms into a proton and emits an electron. Due to electromagnetic interactions, this can result in the ejection of an electron from the atom, a process called internal conversion. Because this process is essentially simultaneous in time, it is pivotal to differentiate between the electron emitted from the nucleus and the internal conversion electron emitted from the atom. Here we apply supervised machine learning algorithms to distinguish between one and two electron events, as well as determine the origin of the electron. With simulated data, we were able to successfully train a convolutional neural network (CNN) to distinguish between a one and two electron event with 96.79% accuracy. Furthermore, we successfully trained a CNN to predict the origin of the electron for one electron events. Our results show promise that our models' performance will generalize to experimental data. Once our models are complete, machine learning will be an important data analysis tool for conversion electron spectroscopy. 

G70.00003: Radio Emission of Supernova Remnants in the Large Magellanic Cloud Kaualani Maneafaiga, John R. Dickel


G70.00004: Mössbauer Investigation of Hafnium OxideHematite Nanoparticles Monica Sorescu, Abigail Ferris Hafniumoxidedoped hematite, xHfO2*(1x)alphaFe2O3, with molar concentrations x=0.1, 0.3, 0.5, and 0.7 was prepared by highenergy ball milling at sample times of BMT=0, 2, 4, 8 and 12 hours. The Mössbauer spectra of the nanoparticle systems were parameterized using NORMOS90. It can be said that concentrations of x=0.1, 0.3 and 0.5 show general trends, but once concentration rose to x=0.7 the sample had more subspectra, allowing new phases to be identified. Each concentration at BMT=0 had one sextet, pertaining to hematite. As the BMT and the concentration of the sample increased, the splitting increased, denoting a greater substitution of the hafnium ions into the hematite lattice. Concentration x=0.1 did not show additional splitting until reaching BMT=4 hours, where the data split from one sextet to two sextets then split further by BMT=12 hours resulting in four sextets and a doublet. Concentration x=0.3 was similar, with BMT=0 displaying only one sextet but BMT=12 hours resulted in five sextets and a doublet necessary for an accurate fit. Concentrations higher than x = 0.3 at BMT=0 required one sextet and one doublet, but no other time had such a pattern aligned with it. 

G70.00005: Experimental MultiPhoton Quantum Walk on a Directed Graph Tong Wu, Josh Izaac, Zixi Li, Kai Wang, Zhaozhong Chen, Shining Zhu, Jingbo Wang, Xiaosong Ma Quantum walks are of crucial importance in the development of quantum information processing algorithms. Recently, another potential application has been proposed, where one could efficiently perform network analysis with quantum walks, especially on vertex centrality ranking. However, it is challenging to rank the centrality of a directed network via quantum walks, since it corresponds to a nonHermitian Hamiltonian, which leads to nonunitary dynamics and thus cannot be simulated by conventional quantum walks. In this presentation, we solve the nonunitary challenge by introducing pseudoHermitian evolutions. We report the first experimental realization of centrality ranking of a directed graph on a photonic platform with multiphoton paritytimesymmetric quantum walks. The experimental results agree well with theoretical predictions. 

G70.00006: Making a Video to Teach a General Audience about Memristors Emma Rhodenizer, Nadine GergelHackett Memristors are a novel nanotechnology with the potential to enable faster and smarter computing. Because of the impact that these nanoelectronic devices could have on our everyday technology, it is important to educate the general public about memristor physics, including their applications and advantages. My research involved learning about the memristorrelated work performed by previous Mary Baldwin University undergraduate physics students and then creating a video describing this work to a general audience. The video was made using a combination of Blender animation software and VideoPro video production software, along with still images and audio. My final product is a YouTube video that explains the Mary Baldwin University memristor research and highlights potential future applications of that research. 

G70.00007: Mössbauer Investigation of Molybdenum TrioxideHematite Nanoparticles Matthew Knauss, Monica Sorescu Molybdenum trioxidedoped hematite, xMoO_{3}*(1x)αFe_{2}O_{3} with molar concentrations x=0.1, 0.3, 0.5, and 0.7 was prepared using highenergy ball milling, taking samples at 0, 2, 4, 8, and 12 hours. The resulting Mössbauer spectra of nanoparticle systems were parametrized using NORMOS90. At ball milling time (BMT) 0 hours, each concentration produced a spectrum consisting of 1 sextet since no lattice substitutions occurred. For all concentrations, a doublet subspectrum emerges from the initial sextet as the BMT increases. For each sample, this appears around BMT = 4 hours and is more intense as the BMT increases, indicating the substitution of Fe^{3+} into the MoO_{3} lattice. Most fits only had 1 sextet except for concentration x =0.1, BMT 4, 8, and 12 hours, and concentration x=0.3, BMT 12 hours. This additional sextet indicates Mo was substituted into the Fe_{2}O_{3} lattice. The absence of this Mo substitution is due to the difference in ionic radii of Mo^{6+ }to Fe^{3+} since the ionic radius of Mo^{6+ }is over twice the ionic radius of Fe^{3+}. Since the substitution of Fe^{3+} into the MoO_{3} was more present than the substitution of Mo^{6+} into Fe_{2}O_{3}, the solid solution has a limited mutual solubility. 

G70.00008: ABSTRACT WITHDRAWN


G70.00009: Investigation of correlation of chemical structure and electronic band structure of FeGa system Jean Alvarez, Kalani Hettiarachchilage, Neel Haldolaarachchige FeGa phase diagram is studied in detail to investigate the correlation of chemical structure and electronic band structure. There were 6 different phases reported on this system only one of them studied in detail experimentally and theoretically. We investigated chemical structure and electronic band structure of all other phases. Electronic band structure revealed an interesting detail of Ga rich nonmagnetic semiconducting phase transforms into a series of magnetic phases towards the Fe rich side. It also revealed that the physical properties of the materials are very sensitive to the stoichiometry and structural deviations of the phases. This study will provide the groundwork to further studies of this materials and also provide an interesting avenue to investigate verity of new materials with potentially interesting physical properties. 

G70.00010: Detection and Classification of High Energy Beta Radiation induced Damage of Raspberry Pi Zero intended for OPAL CubeSat Jonh Mojica Decena, John R Dennison, Brian D Wood, Ryan Martineau, Michael J taylor Radiation survivability of a Raspberry Pi Zero was studied with extended exposures from 0.2 to 2.5 MeV beta radiation of >200krad of total ionizing dose (TID) while undergoing continuous diagnostic cycles. Determining the threshold for radiation damage of inexpensive commercialofftheshelf (COTS) components is critical as a costsaving method in the construction of spacecraft. Characterizing radiation induced damage of COTS with TID allows for proper precautionary measures to maintain spacecraft functionality over the duration of their mission. The specific point and type of failure due to TID is determined to mitigate deleterious effects through enhanced shielding and software or hardware redundancy. TID in the memory and processor units before system failure was measured, along with type, frequency of error, and possibility of system recovery. Careful determination of heat conduction in vacuo of IC’s was conducted to avoid overheating due to delivered battery power and radiation energy deposition. The results will facilitate construction and design of the USUled OPAL CubeSat, to determine if this COTS can survive >200krad TID received during its 12yr mission in LEO orbit. 

G70.00011: Reconstruction of HIPPO Supersonic Gas Jet Target Xianfeng Wang, Shane Moylan, Christopher J Seymour, Luis A Morales, Gwena�lle Gilardy, Daniel J Robertson, Edward Stech, Manoel Couder HIPPO, a supersonic windowless helium gas jet target, is designed and reconstructed as the target for the beam from the 5 MeV 5U electrostatic accelerator located at the Nuclear Science Laboratory (NSL) of the University of Notre Dame. Connected to the target area, St. George recoil separator has been developed to perform, in inverse kinematic, radiative capture experiments of interest to nucleosynthesis. Inverse kinematics, here, means that a heavy ion beam is bombarding a lighter nuclear target. The nozzlecatcher system and chamber have been designed and prepared. A differential pumping system is set up to lower the pressure in the target chamber down to 10^{7} torr in the beamline. The advantages of the windowless design and advantages that gas target compared with the solid target will be discussed. An Arduino based system is set up and now we are able to control the pumps with the touch screen. We have performed the pressure measurement and got the thickness data. Initial experiments are discussed along with plans for future use at the NSL. 

G70.00012: Training Neural Networks for Object Recognition Using Blurred Images Azhar Hussein, Xavier Boix, Tomaso Poggio A shortcoming of deep neural networks is that they require a vast amount of data to train. An example of this is object recognition, a computer vision technique for identifying objects in images or videos. We hypothesized that, when training with few data examples, blurring the input images would cause the neural network to perform better compared to nonblurred images, because of the removal of unnecessary details. In this study, we trained a convolutional neural network on the blurred images, varying the amounts of blur in order to determine how the validation accuracy changes. Our preliminary results suggest that blurring the images does not help when learning from few examples; however, we cannot fully disprove the hypothesis because it requires further experimentation with other data sets and convolutional neural network models. In the future, we can use image blurring to study eccentricity dependence, a property of the human visual system that standard convolutional neural networks do not currently replicate. This research will ultimately bring us closer to understanding and replicating how the human brain processes vision. 

G70.00013: Response of Photoreceptors, Dynamic Modeling of Adaptation and Saturation Anna Smith, Kennedi L Turner, Tirthabir Biswas Photoreceptors have the ability to generate biological responses as a result of stimulation via light. The purpose of this research project is to mathematically model the photoreceptor responses such that we are able to quantitatively capture its key aspects, like the observed adaptation over time and saturation under extreme stimulus. Past photoreceptor models were examined and modified to yield a new dynamic model that was able to provide excellent fits to response of the retinal cells under a variety of stimulus conditions, such as bright and “dark” flashes of light on top of some given initial “background” lighting. Our analysis strongly suggests that just a direct coupling of membrane potential to light is not sufficient to capture the behavior of photoreceptors. Nonlinear coupling between the membrane potential and some “internal” variable that controls adaptation in the cell is necessary to accurately predict the photoreceptor response. On one hand our research may provide insight into the microphysical processes inside the cell, and on the other, help improve exploring the complexities of neural networks. 

G70.00014: Electrospun PEDOT:PSS nanoribbon field effect transistor with a ferroelectric polymer gate insulator Alondra Rosario, Nicholas Pinto Poly(3,4ethylenedioxythiophene) doped with poly(styrene sulfonic acid) – PEDOT:PSS was electrospun to produce high aspect ratio nanoribbons. The ribbons of varying thicknesses were electrically characterized in a field effect transistor (FET) configuration with ferroelectric (FE) poly(vinylidene fluoridetrifluoroethylene)PVDFTrFE as the top gate insulator. The devices exhibited ptype behavior consistent with hole charge transport in PEDOTPSS and a memory window characteristic of a FEFET. Such a memory effect has not been observed before in PEDOTPSS. Thinner films exhibited stronger field effect with a change in the channel current of 104% in the on and off states. The charge mobility reached a maximum of 3 cm^{2}/Vs for the 300nm thick nanoribbon. Thicker films did not show any field effect, suggesting that it is an effect confined to the PEDOTPSS/PVDFTrFE interface and does not penetrate deep into the bulk of the PEDOTPSS film. 

G70.00015: A Schottky diode fabricated by crossing MoS_{2} with an electrospun PEDOTPSS nanoribbon Kelotchi Figueroa, José Perez, Ahmad Matar Abed, Idalia Ramos, Nicholas Pinto, Mengqiang Zhao, Alan T Johnson Monolayer MoS_{2} was grown via chemical vapor deposition while PEDOTPSS nanoribbons were fabricated via electrospinning. Each of these materials was electrically characterized separately in a field effect transistor configuration using SiO_{2} as the gate dielectric. MoS_{2} exhibited ntype behavior while PEDOTPSS showed an Ohmic response. By crossing MoS_{2} with a PEDOTPSS nanoribbon, the currentvoltage curve across the junction was nonlinear and similar to that of a diode. When a positive (negative) voltage was applied to PEDOTPSS (MoS_{2}), the device turned on in the first quadrant of the IV curve. Reversing the external connections resulted in the diode turning on in the third quadrant. The rectification ratio was 625 and the turnon voltage was 0.1V. The device output data was analyzed using the standard thermionic emission model of a Schottky junction yielding an ideality parameter of 1.9 and a barrier height of 0.18eV. A low turn voltage from our diode makes it better for small signal detection and has the advantages of having a higher ac rectification efficiency and a lower power loss compared to standard Si or Ge pn diodes. 

G70.00016: Investigation into the Interface Between Salt Solutions and Hydrophobic Surfaces ANTHONY FLORIMBIO, Cayton Hornberger, Zachary Zoll, Adele Poynor When water is forced into contact with a hydrophobic surface a depletion layer, a region of low density water, is formed at the interface. In nature surfaces do not deal with pure water, rather instead they interact with various aqueous salt solutions. We study octadecanethiol, a hydrophobic selfassembled monolayer, and mercaptoundecanoic, a hydrophilic selfassembled monolayer, in various aqueous salt solutions.We use contact angle measurements, scanning electron microscopy, and surface plasmon resonance to study the interfacial properties of these surfaces. 

G70.00017: Exploring how protamine folds DNA in sperm Yuxing Ma, Adam D. D. Smith, Ashley Carter DNA compaction is crucial for the transmission of genetic information. In sperm, the protein protamine binds to the major groove of DNA and compacts the DNA more tightly than histones. The more highly folded the DNA, the more hydrodynamic the sperm and the more likely it will reach the oocyte without UV damage. To understand the mechanism by which protamine packs DNA, we used an in vitro tethered particle motion assay and video microscopy to visualize the folding of 25 nm DNA. Because this length is shorter than the diameter of a DNAprotamine loop, we did not expect the DNA to fold. However, when we graphed the standard deviation of beads' motion over time, we found that the standard deviation decreases as protamine concentration increases. Our results suggest that protamine can fold shortlength DNA molecules. Understanding the process by which this interaction occurs has applications in male infertility, epigenetics, and nanoengineering. 

G70.00018: AFM analysis of protamineinduced compaction in shortlength DNA fragments Ryan McMillan, Luka Devenica, Ashley Carter During spermatogenesis, small, positively charged protamine proteins dramatically condense the DNA in the nucleus. This tight compaction both minimizes hydrodynamic drag on the sperm and protects the DNA from ultraviolet radiation. Protamine also is an excellent candidate for use in nanoengineering as a way to selfassemble DNA nanostructures. Here our goal is elucidate the physical mechanism for how protamine causes DNA to fold into a ring of ~50 nm in diameter. To study this question, we used an atomic force microscope (AFM) to image protamineDNA complexes. By varying the concentration of protamine in the assay, we are able to image the intermediate steps in the folding pathway. We find that shortlength (50 nm or less) DNA fragments form half loops that become increasingly more folded as the protamine concentration is increased. Future work will investigate whether this looping is induced by enthalpic or entropic forces. 

G70.00019: Simulation of long range ordering in an ionic liquid using molecular dynamics Alexis Puyleart, Emily Dalbey, Ralph Wheeler In the last few years, a startling amount of electronic devices have been recalled due to issues regarding the safety of the battery. This is because the current electrolytes in batteries are volatile and flammable. Ionic liquids are currently being explored as possible alternatives to current electrolytes in lithium ion batteries. As a result, it is important to understand the structure of ionic liquids when lithium is added. Experimental structure factors of NalkylNmethylpyrrolidinium and bis(trifluoromethylsulfonyl)imide (TFSI) from xray diffraction data show three peaks at low wavenumber values: a prepeak, a second peak due to charge alternation, and a third peak due to charge adjacency. Molecular dynamics computer simulations were used to calculate structure factors and investigate why the charge alternation peak disappears after adding LiTFSI. 

G70.00020: Electronic Band Structure Studies of Binary Iridates in IrGa Phase Diagram David Gordon, Kalani Hettiarachchilage, Neel Haldolaarachchige Binary iridates in IrGa system is studied in detail by using the computational method. Correlation of chemical structure and electronic band structure of IrGa are investigated in detail. There were several different phases reported on this systems but none of them were studied in detail experimentally or computationally. Electronic band structure studies revealed an interesting detail of the phases of IrGa systems. This study also suggested that the physical properties of these materials can be tuned by using the stoichiometry and structural deviations of the phases. We also propose that some of the phases could be interesting to search for novel physical properties. This result will generate the enthusiasm of experimentalist to further studies these iridate materials and also open a new avenue to broaden the search for new materials with potentially important novel physical properties. 

G70.00021: Computational Modelling of the PhotoField Effect William Schenken, Reuben T Collins, Idemudia Airuoyo The photoresponse of a thin film transistor depends on the mode of operation the transistor is in, in an effect known as the photofield effect. The extent of this effect then depends on the properties of material composing the transistor. This intensity and state dependent photoresponse is explored in amorphous silicon (aSi) thin film transistors (TFTs) with computational modelling. Results of the numerical simulation agree with observed experimental results. Possible sources of the effect are analyzed and related to parameters in the model. The results from aSi TFTs are then related to experimental results of TFTs consisting of aSi embedded with nanocrystalline silicon (ncSi) quantum dots (the composite material denoted as a/ncSi), and future work involving a more explicit relationship between the parameters in the model and the properties of a/ncSi is discussed. 

G70.00022: Optimization of Serpentine Micromixers with NonRectangular CrossSections Joshua Clark, Petru Stefan Fodor, Chandrasekhar Kothapalli Serpentine or spiralshaped microchannels have been popular choices for microfluidic mixers due to their relatively easy fabrication and possibility for reuse. The technique used in these types of microchannels aims to utilize the crosssectional transversal (Dean) flows experienced by the fluids as they round a curved channel. Because of the reliance on centrifugal forces the mixing quality is strongly Reynolds numberdependent, with quality mixing occuring only at Re>100. It has been shown that the use of channels with nonrectangular crosssections can be used as an effective strategy in this type of design to induce mixing at much lower flow rates. In this work, we seek to optimize the geometrical parameters of these channels to maximize their overall mixing performance. The results of the optimization process were obtained numerically through computational solutions of the flow fields and fluid concentration. Experimental results are also included showcasing the increase in mixing quality. We found that our optimized designs substantially outperformed standard serpentine geometries with rapid mixing being achievable down to Re~20. 

G70.00023: WITHDRAWN ABSTRACT


G70.00024: Evidence of Particles During Electrochemical PdD Codeposition Micah Karahadian, Heide M Doss Palladium deuterium codeposition is used to explore condensed matter reactions. CR39, a thermoset resin is a well characterized integrative detector that, when etched, shows tracks created by energetic charged particles produced in nuclear reactions. Analysis of tracks provides particle minimum energy and insights into identification (e.g. alpha versus proton). Certain tracks infer neutrons interacting with carbon atoms within the detector, resulting primarily in three alphas (e.g. triple tracks). We report our findings of Pd/D codeposition on Au wire in an electrolytic cell, and our controls. Our findings imply the presence of nuclear reactions. 

G70.00025: Probing a Mixed Dark Matter Scenario with the CLASS Code Addy Evans, Rouzbeh Allahverdi The purpose of our research is to further understand the physical properties of dark matter. We present the physical constraints of a mixed dark matter scenario in which there is a mixture of both warm and cold dark matter. The warm dark matter in our model arises from a nonthermal decay of a heavy particle that occurs when the Universe is ~ 0.11 second old. By using the CLASS code, we have plotted the linear matter power spectrum of these scenarios and compared them to the observed matter power spectrum of Lymanalpha forests. We find that warm dark matter with a mass of 50 GeV to 450 GeV can exist in fractional amounts, while warm dark matter with a mass of 460 GeV to 1 TeV can potentially comprise the entire dark matter population. 

G70.00026: Room Temperature Field Effect Investigation in SrIO3/SrTiO3 Thin Films Alejandro Zafra, Jian Liu, Stephen A Tsui, Lin Hao Insulating thin films of layered SrIrO3/SrTiO3 (SISTO) have been chosen as a candidate system in which to explore field effect resistance switching, where the application of an electric field induces a reversible change in the electrical resistance. This allows for the possibility of creating a new field effect transistor (FET). The SISTO films were synthesized via pulsed laser deposition. The resistance was measured at room temperature using the 4wire method. The field effect gate was created by placing an ion gel droplet on the film covered by a sheet of Pt foil. Preliminary data demonstrates the change of electrical resistance of the film upon application of voltage across the ion gel. Future work will include improving the experimental setup to reduce the likely temperaturedependent drift in the resistance measurements and investigating the effects of altering the voltage. 

G70.00027: Temperature Dependent SelfAssembly of 9,10dibromoanthracene on Ag(111) Cory F. Ashworth, Tristan D. Blackwell, Timothy J. Fuhrer, Thomas P Pearl, Shawn Huston Thin film growth of 9,10dibromoanthracene (DBA) on Ag(111) up to a full monolayer has been studied via UHV scanning tunneling microscopy (STM). Prior studies of thin film growth for deposition of this molecule on the same substrate while at room temperature has demonstrated debromination of the molecule followed by selfassembly of a chainlike structure mediated by Ag adatoms [1]. However, our results show no debromination and instead a honeycomb network is formed. The reason for this discrepancy is still under investigation, with present studies focused on accurately cataloguing substrate temperature during film growth. We note that other STM studies of brominated organic molecules grown at reduced substrate temperatures have shown debromination of those molecules only upon subsequent annealing of the film [2]. A molecular model of our film growth will be presented, with the organization of the film most likely driven by weak brominebromine bonding between adjacent molecules. 

G70.00028: Systemslevel Transcriptomic Analyses for Comprehensive Characterization of the IgG3 B Cell Subclass Anush Devadhasan Prior studies have suggested that HIV antiviral control may be achieved via the induction of highly polyfunctional IgG3 antibodies (Abs). Here we employ a systems approach to characterize the IgG3 transcriptional profile by identifying intrinsic differences between IgG3 B cells vs IgG1 and IgM B cells that might suggest mechanisms by which B cell molecular circuitry can be programmed to induce and preserve IgG3 Abs. Strikingly, differentially expressed genes between isotype pairs reveal IgG3 is substantially different from other subclasses independent of patent phenotype and time point and subsequently observe clustering by subclass, as opposed to phenotype/time point. Significantly enriched KEGG and Hallmark pathways and GSEA immunological signatures in differentially expressed genes indicate increased activation of basic cellular processes and restriction of transient signaling in IgG3. Therefore this study 1) demonstrates transcriptomic analyses are an effective strategy for characterization of highly homogenous cell subpopulations and 2) offers critical insight into systems level transcriptional signatures of the IgG3 subclass, paving the path for future downstream experiments. 

G70.00029: Robust laser frequency drift tracking and data sharing platform to perform qubit calibration for an ion trap quantum computer Shuqi Xu, Eli Megidish, WeiTing Chen, Joseph Broz, Clemens Matthiesen, Hartmut Haeffner One of the fundamental requirements for using optical transitions as qubits is an accurate control of the phase of the electric field of the laser field driving the qubit transition. For this it is necessary to calibrate the laser frequency accurately. The calibration can be achieved by simple spectroscopy scan of the optical transition. Alternatively, one can use Ramsey spectroscopy achieving a higher signaltonoise ratio in a given time. However, if the laser frequency jumps significantly with respect to the atomic transition, one may switch by one Ramsey fringe. Here we implement a laser frequency drift tracker for the Ca^{+} quadrupole transition at 729 nm based on the Ramsey method. An algorithm adjusts automatically the Ramsey wait time to stay in tracking range while maintaining the accuracy. In addition, we develop a platform such that different ion trap experiments can share and use tracking results from other ion trap experiments. 

G70.00030: Measurements with PositionMomentum Entangled Photons Zeenat Baig, Zoya Shafique, Sean James Bentley We constructed a system to generate positionmomentum entangled photons. These particles interact non locally therefore anything done to one photon affects the other. We produce 405 nm photons that become two entangled 810 nm photons through the process of spontaneous parametric down conversion. We are able to extract data about the position and momentum properties such as joint uncertainties of these photons. The spatial uncertainty was found through nearfield detection, a process where we imaged our crystal onto a single slit. Through farfield detection, we were able to get the momentum uncertainty. This involved focusing the beam onto slits which resulted in a fourier transform. Once optimized, we used our system as the basis for a highsensitivity magnetic field sensor. 

G70.00031: The Dynamics of Polymeric Microgels with Varying Crosslinker Concentration Samantha Tietjen, Jacob Adamczyk, Kiril Streletzky Polymeric microgels synthesized by crosslinking amphiphilic polymer chains exhibit a reversible volume phase transition under the effect of environmental conditions such as temperature of a solution. The common behavior of these microgels is to deswell from a large to small size with an increase in temperature above the transition. Microgels in this study were synthesized by crosslinking a polysaccharide in a surfactant solution. When varying the amount of crosslinker by a factor of a hundred, three apparent behavioral regimes emerged from light scattering measurements: at low crosslinker concentrations, microgels deswelled and became more diffusive with temperature increase, at midrange crosslinker concentrations they didn’t significantly change their size with temperature, and, at high concentrations, microgels showed a reversed behavior, where they grew and became less diffusive with increase in temperature. These apparent regimes are possibly due to nonuniform crosslinker distribution in the polymer microgel, which becomes more prevalent at large concentrations of the crosslinker. 

G70.00032: Models for diffusion and Island growth of hydrogen on graphene Sky Semone, Majid Karimi, Carl LeBlond, Gian Franco Vidali A Hydrogen atom can either physisorb or chemisorb on a graphene surface. A model for the diffusion of a hydrogen atom, between nearest neighbor chemisorption sites on graphene surface, is presented. The parameters of the model are optimized against a full set of barriers obtained from the first principles. The energy barrier of the hopping hydrogen is related to the local environment of the hopping hydrogen. In model I, the local environment of the migrating hydrogen include four sites (or 24 configurations). Depending on whether these sites are occupied or empty a total of sixteen configurations (barriers) are required to be calculated. Due to symmetry, only 10 of these configurations are independent. In model II, the local environment of the migrating hydrogen include eight sites (28 configurations). Out of these 256 configurations, a little more than half of them are independent. Models I and II have three and four parameters, respectively. The parameters of the two models are obtained by fitting the barriers to the corresponding ones from the Quantum Espresso code. The comparisons between the models and the first principles would serve as a gauge as to whether extension to a larger local environment is warranted. 

G70.00033: Modeling Superconducting Resonators for Astronomical Photon Detection Daniel Morales, Karwan Rostem, Edward J Wollack The current generation of Cosmic Microwave Background (CMB) polarization experiments demand highperformance backgroundlimited sensor arrays to achieve the desired levels of instrument sensitivity. One particularly promising approach, known as MKIDs (Microwave Kinetic Inductance Detector), is based on monitoring the response of a resonator in the presence of radiation with sufficient energy to influence the device’s superconducting properties. This sensor architecture is amendable to realizing high focal plane density while maintaining readout with low parasitic thermal loads in a sub –kelvin cryogenic environment. We explore the use of a finite element analysis method solver to carry out electromagnetic simulations of representative sensor geometries. 

G70.00034: ABSTRACT WITHDRAWN

(Author Not Attending)

G70.00035: Fabrication and characterization of multicoil neural probes Amelia Culp, Luke D'Imperio, Michael J Naughton, Andrew McCrossan There is virtue in longterm neural stimulation for the treatment of symptoms associated with neurological disorders. To date, implanted electrical probes^{1} have had great success in mitigating seizures and symptoms of e.g. Parkinson’s disease and other pathologies. However, chronic stimulation has proven challenging as electrode performance degrades over time. Alternatively, new technologies are exploring electrical stimulation via changing magnetic fields^{2}, harnessing the physical properties set out by Maxwell’s equations. Most magnetic neural probes use a single coil design on silicon substrates; multiple coils using substrate materials with increased pliability may improve these technologies. Here, we discuss the modeling, making, and measuring of multicoil magnetic probes microfabricated on flexible polymer substrates for potential longterm neural stimulation. This novel device design is characterized toward the goal of recording of devicedriven action potentials in spatially removed neurons. 

G70.00036: Phase Transitions in Polymeric Gels Induced by Crosslinking Entropy Jacob Adamczyk, Miron Kaufman, Kiril Streletzky Microgels are polymerbased particles which can change size and shape during volume phase transitions in response to external stimuli. We have specifically investigated microgels which respond to changes in temperature. Hydrodynamic radii were obtained from light scattering data on Hydroxypropylcellulose (HPC) microgels and then modelled with the standard FloryHuggins theory. We present a numerical study of a thermodynamic theory (M. Kaufman, Entropy, 20(7), 501, 2018) which includes the entropy associated with crosslinking between polyfunctionals and monomers at the ends of linear polymers. This theory predicts a strong firstorder transition due to the saturation of possible crosslinks when the number of polyfunctionals is of the same order of magnitude as the number of polymers. We will present numerical results based on this thermodynamic model. 

G70.00037: Modeling transport in paper microfluidics Rayleigh Parker, Tim Atherton, Charles Mace Paper based microfluidic devices are extremely promising as an inexpensive and highly customizable platform for assays. Flow and particle transport in these highly porous and disordered materials are not well characterized, however, presenting a challenge for the construction of reliable devices that may require welltimed transport of cells and media such as blood. In this work, we identify design and material parameters crucial to transport, and experimentally characterize their influence through a sequence of test devices, where the fluid flow is tracked using our new opensource software package developed for this purpose. Measurements are compared with theoretical modeling to identify the physical processes and relevant timescales involved. Prospects for control and design of future devices will also be discussed. 

G70.00038: WITHDRAWN ABSTRACT


G70.00039: The Yarkovsky Effect on NearEarth Asteroid (101955) Bennu, Target of the OSIRISRex Mission: A review of the literature, by Robert Melikyan Robert Melikyan The Yarkovsky effect is a nongravitational phenomenon resulting from anisotropic thermal emissions of rotating asteroids. It took more than 100 years between theory and detection (first seen in asteroid 2489 Golevka in 2003). Now, the nearearth asteroid 101955 Bennu has shown a mean semimajor axis drift da/dt = 284 ± 1.5 m/year due to the Yarkovsky effect. Nongravitational drift can greatly affect the probability of asteroid impact with earth making accurate modeling of the Yarkovsky effect a high priority for NASA. The OSIRISREx mission is currently delivering a satellite into orbit around Bennu. Amongst the mission objectives is the measurement of the asteroid’s thermophysical properties that contribute to the Yarkovsky effect, such as the thermal conductivity of the surface. This is important because the observations necessary to measure thermophysical properties from Earth are much more difficult than from a spacecraft platform. Another difficulty is that the highly elliptical orbits of most nearearth asteroids can greatly increase error. Bennu, with the “eyes” of the OSIRISREx mission, acts as the perfect aid for observing and understanding the characteristics of this important nongravitational effect that makes asteroid orbits so hard to predict into the future. 

G70.00040: Optical Properties of MBEgrown (Bi 1x Sb x ) 2 Te 3 Thin Films Phoebe Killea, Frank C Peiris, Anthony R. Richardella, Timothy Pillsbury, Nitin Samarth Spectroscopic ellipsometry was used to determine the dielectric functions of a series of (Bi1xSbx)2Te3 thin films. The films were grown using molecular beam epitaxy and were deposited on InP substrates. Xray diffraction, XPS and AFM experiments indicated that the films were of highquality. Ellipsometry measurements were obtained in the spectral range between 0.05 eV and 6 eV. A standard inversion technique was used to model the ellipsometry spectra, which produced the dielectric functions of each of (Bi1xSbx)2Te3 thin films. By representing the dielectric function with KramersKronigconsistent oscillators, the fundamental band gap and the higher order transitions of these films were obtained. A Drude oscillator, which represents the absorption of free carriers, was needed to model some films. 

G70.00041: Developing an Interactive Demonstration for the Science of Smell Carissa Giuliano, Matthew Wright We present our work towards developing an interactive demonstration for middle school and high school students on the science behind how we smell. We will discuss the results of our literature search which shows there are three models for how we smell: the Lock and Key model, the Vibration Theory model, and the most widely accepted model that combines the two. We will discuss how we plan to demonstrate these three concepts to young science students and how we plan to us it as a tool to generate interest in science. 

G70.00042: Progress toward Coherent Control of Ultracold Collisions with FrequencyChirped Laser Light Olivia Chierchio, Zafir Momin, Michael Robbins, Areeba Khalid, Matthew Wright Frequencychirped laser light as recently been shown to coherently control collisions and photoassoication. We are planning to use short (~ 3 ns), intense (> 100 mW/cm^{2}), frequencychirped (~1 GHz in 6ns) laser light to control excitedstate collisions between Rb atoms in a MOT. We will discuss our progress towards this aim, including stabilization of our MOT and our computer control system. 

G70.00043: ABSTRACT WITHDRAWN


G70.00044: The Effects of Ionized Impurities on the Nanoscale Spatial Distribution of the Schottky Barrier Steven Gassner, Jack Rogers, Hyeonseon Choi, Westly Nolting, Vincent LaBella The influence of ionized impurities in the semiconductor upon the local Schottky barrier height of a metalsemiconductor interface is important for contacts in nanoscale devices. A computational model simulates spatiallyresolved measurements of the electrostatic potential of various metalsemiconductor interfaces acquired using ballistic electron emission microscopy (BEEM), an STMbased technique. The model assumes a uniform charge density with a set of point charges close to the interface, and generates simulated datasets in the form of Schottky barrier height maps and histograms. The introduction of localized charges causes skewing of the distributions, which are compared to BEEM measurements of Au/Si and Cu/Si Schottky barrier height maps. 

G70.00045: A High Power Setup to Test Optical Coatings Andrew Poverman, Bruno Becher, Logan Kaelbling, Isobel Curtin, Riti Bahl, Antonios Kontos To detect gravitational waves, the LIGO detectors need to limit the noise from multiple sources. Noise related to the quality and characteristics of the coating that is used on the test masses is one of the most important and most difficult to mitigate. Significant effort is invested in finding new types of coatings that satisfy the many stringent requirements of LIGO, which include low thermal noise, low scattering and low absorption. In addition, these coatings need to withstand high CW power without exhibiting any significant deterioration. It is therefore crucial to develop optical setups that will measure all the relevant coating properties, and under conditions similar to LIGO. Here we describe one such setup at Bard College. The main characteristics of our setup include a high finesse cavity inside an ultrahigh vacuum chamber, in which mirror samples will be tested for scattering and aging over long periods of time. 

G70.00046: Directed SelfAssembly of Nanoparticles under Electric Fields Matthew Withers, Mitchell Roberts, Dan Mazilu, Irina Mazilu We develop an experimental and theoretical approach to study the effect of electric bias on particlecoverage densities produced during nanoparticle selfassembly. Experimentally, we utilize a parallel plate capacitor to allow for the application of a uniform external electric field during the selfassembly of SiO_{2} nanoparticles on glass slides. We refer to this procedure as directed selfassembly of monolayers (DSAM). To determine particlecoverage densities, we use scanning electron microscopy. In our theoretical analysis, we modify existing cooperative sequential adsorption models to account for diffusion under an applied electric field. We then apply the mean field approximation to these modified models to obtain master equations, which we solve for particlecoverage densities. To ascertain the validity of these models, we compare computer simulations produced using our theoretical approach to our experimental data. 

G70.00047: Modeling Senate Voting Behavior using Mathematical Modeling. Anthony Lorson, Sho Gibbs, Justin Pusztay, Will Hanstedt, Irina Mazilu Using purely quantitative methods to analyze and explain Congress’ actions is rare, yet has the potential to be extremely valuable. We aim to model the voting patterns of the Senate by adapting the Ising model and incorporating economic game theory, with each individual senator being a node with a votingstate and a partisanship value. Our assumptions include symmetry between voting yes and no before the introduction of partisanship and a lack of an external field. The coupling constants of the Ising model reflect the nature of the issue at hand and are individualized for each senator, reflecting their own partisanship as well as the positions of senators who interact with them. The stochastic model was run using Monte Carlo simulations in Python, with several different graph types allowing for multiple ways for senators to be connected to one another. By looking at the properties of the graph such as magnetization and correlations between nodes, we hope to gain insight into how the Senate operates. 

G70.00048: Using an Arduino in a Coupled Logistic Map Circuit to Explore Basins of Attraction for Symmetrybroken States Moyi Tian, Houssemeddine Mhiri, Lars Q English L’Her et al. [1] recently constructed a circuit designed to implement the logistic map electronically, and thus generated bifurcation diagrams in growth rate, r, as well as in coupling parameter, ε, for two coupled maps. We show that in the coupled logisticmap system, the dynamics is not only determined by r and ε, but also by the initial conditions, due to the multistability of different solutions. By experimentally adding control over initial conditions and incorporating an Arduino Uno Microcontroller, we explore basins of attraction associated with symmetric states, symmetrybroken states and phaseshifted states. 

G70.00049: Implementation of a Causal Spectral Decomposition Representation for the Neutron Star Equation of State for Gravitational Wave Parameter Estimation Devon Nothard, Leslie Wade On August 17, 2017 LIGO observed a binary neutron star merger 130 million lightyears away by detecting ripples in the fabric of spacetime called gravitational waves. Information about the neutron star equation of state (EOS), an equation relating the state variables of a system, is encoded in these waves. Currently the neutron star EOS is highly unconstrained. However, constraining this equation through gravitational wave measurements may provide us unprecedented knowledge about a naturally occurring source of nuclear matter at densities unachievable in a laboratory. Theoretical physicists use knowledge of microscopic and thermodynamic properties of nuclear matter in order to invent potential candidate EOSs that are consistent with current neutron star observations. Prior to LIGO’s monumental discovery, NS observations and EOS constraints came exclusively via optical telescopes. However, we can extract NS EOS information from gravitational waves as well. In this project, I incorporated an EOS model with physical conditions such as causality and thermodynamic stability built in. I have developed software that will be incorporated into LIGO’s parameter estimation algorithms to measure the neutron star EOS from future gravitational wave observations using this model. 

G70.00050: 3Color TwoBeam Broadband Nonlinear Frequency Mixing: From Physics to Applications for Spectroscopy Benny Schundelmier, Laszlo Janos Ujj We report the theoretical summary of 3color twobeam broadband nonlinear frequency mixing by using the doublesided Feynman diagrams and the phenomenological picture of the light matter interactions. We measured the intensity dependence of the signal beam via excitation beams and recorded the scattering spectra that originated from molecular solutions and crystals. Pure vibrational spectra were extracted from the measured spectra with model independent phase retrieval methods. We have used our spectroscopy system published recently [1] to characterize the method. We showed that the method is extremely useful to measure molecular vibrational and vibronic spectra in the low frequency, terahertz range. 

G70.00051: HIV1 Gag Protein Nanoparticle Systems: Assembly and Viral Inhibition Strategies Jaime Garcia, Danitza Vasquez, Delvin Caraballo, Delaney Alejandro, Daniel RamosPerez, Marvin Bayro Current drug therapies available to individuals infected with the HIV1 virus work to target reverse transcriptase and the viral protease via a drug cocktail. However, during the process of maturation in HIV1, viral protease cleaves Gag and initiates conformational changes in CA proteins which foster its assembly into the capsid, a fullerene shaped shell composed of ~1500 copies of CA. This capsid houses the viral genetic information and poses as a viable target for treatment to combat the virus. Current knowledge of the mechanisms and processes of this conformational shift is very limited. To enhance our understanding of the process of maturation we studied the effects of protein crowding by constructing Gag viruslike particles (VLP’s) alone (control), in the presence of Cterminal capsid, cytochromec, lipids, and ribonucleic acid so we can study the effects their presence may have on Gag’s ability to selfassemble. Our results indicate that Gag retains its ability to selfassemble into VLP’s despite protein crowding effects and competitive inhibition of its dimerization interface. 

G70.00052: Molecular Dynamics Simulations of Patterned Complex Coacervates Natalia Markiewicz, Tyler Lytle, Charles E. Sing Complex coacervation is the liquidliquid phase separation of polyelectrolytes in aqueous salt solution into a polymerdense phase (coacervate), and a polymerdilute phase (supernatant). These materials are simplified analogues of membraneless compartments in cells, where the sequence of charge has been shown to alter resistance to the presence of salt. Previous work using Monte Carlo simulations demonstrated that changing the sequence of charged and neutral monomers while keeping the charge fraction constant alters the extent of phase separation. We have run molecular dynamics simulations to elucidate the interplay between charge fraction and charge sequence, showing comparisons to existing Monte Carlo simulations and experimental data demonstrating that charge blockiness enhances phase separation. This model is then used to demonstrate the structural effects of varying the charge fraction, in particular showing the emergence of microphase separation at low salt concentrations for blocky polyelectrolytes. 

G70.00053: Analysis and Comparison of Light Intensity Spectra Using Wavelet and Fourier Analysis. Briena Feltner, Joseph Trout This is a continuation of research on the analysis of light intensity spectra of stars that began in the Fall 2017. Using Fourier Analysis and Wavelet analysis, both are typically used for analyzing stellar light curves, a comparison of the recorded light spectra can be made between a space telescope and a ground telescope. Long term, continuous time series of light intensities are needed for the analysis of astronomical phenomena such as the orbit of previously unseen planets. Since the space telescope time series records are sometimes missing data, it has been suggested that land based telescopes can be used to fill in the missing data. This poster presents the comparison of data collected and analyzed with Fourier Analysis and Wavelet analysis. 

G70.00054: Morlet wavelet analysis of planetary atmospheres. Vatsala Adile, Espen Fredrick, Darsa Donelan This study investigated the use of Morlet wavelet analysis in the detection of gravity wave structure in the atmosphere of terrestrial bodies, primarily Mars, Venus, and Titan. Atmospheric profiles from data collected by planetary probes and satellites were processed to generate 2D images of wave structure in each analyzed atmosphere. The analysis shows a correlation between vertical wave structure at altitudes and wavelengths to those previously found using other methods such as comparing temperature gradient profiles to the dry adiabatic lapse rate. This suggests the use of Morlet wavelet analysis as a viable alternative to previously used methods for detection of smallscale variability. 

G70.00055: The Coefficient of restitution by Microcontrollers Thy Doan Mai Le, Dan A. Briotta The project began with the traditional setup for a coefficiency of restitution experiment that is failing and has been abandoned by students of Advanced Lab, which was a call for a major upgrade. After the project is complete, the experimental setup now has a completely new circuitry with calibrated frequency responses, the ability to handle a wider range of inputs, a digitizer circuit, an Arduino and an accompanying program for data acquisition and a Python GUI that takes in data via serial connection from the Arduino, plots the live data and analyzes it to find the coefficient of resitution. The goal of the project was to reignite students' interest in the classical experiment, expose students to microcontrollers and give students an opportunity to learn how to program parts of a system to work together, all at a very small cost compared to previous setups using NI devices and Matlab interfaces. 

G70.00056: Effects of structural order on magnetic properties of S = 1 [Ni(HF_{2})(pyz)_{2}]PF_{6 }(pyz = pyrazine) Ashley Glover, Jamie Manson, Sam Curley, Robert Williams, Paul Goddard, John Singleton, Saul H. Lapidus, Roger Johnson, Pascal Manuel, Wei Zhou, Jesper Bendix We have discovered a third polymorph in the [Ni(HF_{2})(pyz)_{2}]PF_{6} family of coordination polymers. As compared to the previously published structures that possess structurally ordered frameworks^{1}, a new example features a disordered, monoclinic unit cell. This new variant allows us to examine the effects of structural order and disorder on superexchange pathways, specifically along the NiFHFNi and NipyzNi directions. We consider the local distortions to the Ni(II) coordination sphere and the geometries afforded by the ligands. This presentation will address the possible discrepancies in magnetic properties for these polymorphs as gleaned by examination of their structures. 

G70.00057: Applying Machine Learning to Ultrasound Computational Simulations to Determine Scatterer Location Naomi Brandt, Nguyen Nguyen, Maria Teresa Herd In the field of ultrasound imaging, it has been theorized that imaging noise, known as speckle, may be the product of unresolvable scatterers. This would result in certain speckling patterns revealing themselves over large datasets, which could be utilized to predict the early formation of tumors. Such a dataset would be difficult to analyze by hand, but machine learning algorithms can be used to recognize these patterns in an effective manner. As of now, few attempts have been made apply machine learning to predict scatterer placement from ultrasound scans. 

G70.00058: Field Electron Emission of Hafnium Carbide Morgan Chamberlain, William Mackie, Josh Lovell Hafnium carbide, or HfC, is a robust material whose high melting point makes it an advantageous electron source for a variety of uses, including imaging. This research focused on the effects of an applied field at high temperature on HfC crystals, which induces a faceting effect over time. The cause of this faceting was studied to determine whether it could be correlated to evaporation or selfdiffusion during use. The method for electrochemically etching hafnium carbide cathodes was also optimized, and the crystallographic geometry of the tip surfaces was studied using field emission microscopy. 
(Author Not Attending)

G70.00059: Comparison of CapacitanceVoltage, CurrentVoltage, and BEEM Measurements of MetalGrapheneSemiconductor Schottky Barrier Heights Hyeonseon Choi, Jack Rogers, Steven Gassner, Westly Nolting, Vincent LaBella Capacitancevoltage, currentvoltage, and ballistic electron emission microscopy (BEEM) measurements were performed to determine the Schottky Barrier Heights of Au/Si and Au/graphene/Si samples. In addition, measurements were performed on a commercial diode for reference. Data were acquired as a function of temperature, which indicate that the graphene had little effect upon the barrier heights that were measured. 

G70.00060: SelfAssembly of Spheres on a Cone Surface Talha Rehman, Nabila Tanjeem, Vinothan N Manoharan Selfassembly in confined space can lead to formation of unique 3D structures. We study selfassembly of submicronsized colloidal spheres on the surface of a micronsized cone. Fabrication of micronsized cones is challenging using conventional photolithography. We explored alternative techniques for fabrication of cones. By using a 3D laser lithography tool called Nanoscribe, we successfully manufactured cones of various cone angles and diameters. By using a micropipette puller, we pulled glass capillary tubes into cones with very smooth surfaces. We performed experiments to selfassemble colloidal spheres on both types of conical surfaces. To assemble spheres, we use depletion interaction. It results in a shortranged attraction between the spheres, and between the spheres and the conical surface. We observed crystal growth on the cones that were fabricated from glass capillary tubes. This result suggests that a smoother cone surface is preferred to study selfassembly on a cone using depletion interaction. 

G70.00061: Measurement of the Tissue Properties of Three Cell Lines using Quantitative Ultrasound Penelope Taylor, Amy Longstreth, Maria Teresa Herd We are measuring the ultrasonic characteristics of cells to find the fundamental differences between cancerous and noncancerous cells by calculating and comparing the attenuation and speed of sound. We are comparing both the attenuation and the speed of sound because these properties are dependent on the medium being used, and thus should have differences in their ultrasonic characteristics. In this experiment, the three cell lines being used are prostate cells, cancerous colon cells, and cancerous prostate cells. To test for these differences, we are using unfocused transducers of 5, 10, and 15 MHz to find the data for the cumulative range of 2 to 18 MHz. These transducers are placed in water and aligned for optimal wave amplitude travelling between them. The results of the comparisons of cell lines shows a noticeable difference between colon cancer and the other two cell lines, prostate and prostate cancer. The difference between prostate cells and prostate cancer cells is much less significant. This research may lead to the ability to better detect whether lesions are cancerous or noncancerous using the noninvasive method of quantitative ultrasound. 

G70.00062: Systematic Removal of Self Assembled Monolayers from Au(111) surfaces, investigated via Atomic Force Microscopy and Contact Angle Measurements Indrajith Senevirathne, Kelly M Gerrity SelfAssembled Monolayers (SAMs) of thiols on Au(111) surface on mica substrates are used in many instances to study various proof of concept devices such as Nanosensors and Nanoelectronics. However, once used, the Au on mica substrate, upon which the SAM layer sits on, is discarded as surface integrity could deteriorate in the cleaning steps. We have used combinations of organic solvents to critically clean and gently remove the SAM surfaces from the Au(111) substrates. Subsequent surfaces were investigated using Atomic Force Microscopy (AFM) and the Contact Angle measurements. Results were compared with Au(111) surface before SAM deposition and after SAM removal. We have used 1Dodecanethiol as our SAMs on Au(111) surface. AFM was used in intermittent contact mode to image the investigated surfaces. Discussion of the results obtained compared with the existing literature will follow. 

G70.00063: Optical Tweezer Measurements in Chlamydomonas Mauricio Gomez, Corbyn Jones, Wylie Ahmed Optical tweezers have been used to study force uctuations in microscopic systems and 

G70.00064: Conductivity vs. Temperature Measurement for PEDOT:PSS Jose Peralta, Madison Guerrero, Patrick Milan, Layla L Ogletree, Prof Weining Wang Conducting polymers can be applied to a broad range of specialties, such as solar cells, lightdiodes, sensors and other optoelectronics. In particular, poly(3,4ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS), a conducting polymer, is the most popular due to its high conductivity and stability. It has been used widely as contact material in solar cells, which may operate at different temperatures other than room temperature. Because of this, it is important to examine how the polymer, and its characteristics, are affected at different temperatures, which ultimately affect the performance of the polymer and its application in solar cells. 

G70.00065: Development of Apparatus for Simultaneous Measurement of Photocurrent and SHG Austin Kaczmarek, Liuyan Zhao Many studies have been done investigating the second order nonlinear response of noncentrosymmetric materials to gain insight to the electronic structures of these materials. Photocurrent and optical second harmonic generation (SHG) are two second order nonlinear phenomena that share the same form of the second order nonlinear susceptibility tensor but are sensitive to distinct energy regimes of the electronic structure of the material under investigation. We present the development of an experimental apparatus for the simultaneous measurement of these two nonlinear phenomena using an ultrafast laserbased scanning approach. We show that the laser scanning provides a spatial resolution of these two nonlinear responses down to the optical diffraction limit, and the confocal imaging scheme adopted in our design assures a constant incident electric field over a wide scanning area. We also discuss our effort in enhancing these nonlinear responses, by compressing the laser pulse to its transform limit. Finally, we will discuss future opportunities brought by this apparatus, such as developing time resolved scanning nonlinear optical techniques. 

G70.00066: Looking for Variability in Cygnus X1 Bailey Conrad, Alex Storrs We present observations of HDE 226868, the companion to Cygnus X1. Low resolution (R=4.3 Å per pixel) spectra of the visible region, 6500 Å to 3000 Å, made with Maryland Space Grant Consortium’s 0.5meter telescope at John Hopkins University over the summer. This region includes emissions from hydrogen and helium which are shown to be time variable by Gies et al. (2003). We examined these spectra for variability. 

G70.00067: Understanding the determination factors of the formation of large flocks of swimming sperm in viscoelastic fluid Jelani Lyles, Daniel Sussman, Soon Hon Cheong, Susan S Suarez, M. Lisa Manning, ChihKuan Tung


G70.00068: Synthesis and Characterization of Cobalt Ferrite (CoFe_{2}O_{4}) Magnetic Nanoparticles by BallMilling and SolGel Techniques Thomas Longo, Bryan Eigenbrodt, Jeremy Carlo, Arthur Viescas, Georgia C Papaefthymiou Magnetic nanostructures play an important role in nanotechnology allowing for technological advances in electronic devices, photocatalysis, sustainable energy, biotechnology and medicine. In particular, cobalt ferrite (CoFe_{2}O_{4}) magnetic nanoparticles (MNP) have strong uniaxial magnetic moments, which allow for applications in hyperthermia and targeted drug delivery. Therefore, these particles were synthesized using two different techniques: mechanochemical ballmilling and solgel. Using Mössbauer Spectroscopy, XRay diffraction, Transmission Electron Microscopy, SQUID magnetometry, and Specific Absorption Rate (SAR) measurements, their magnetic, structural, and thermal transfer characteristics were analyzed and compared to maghemite (gammaFe_{2}O_{3}) and magnetite (Fe_{3}O_{4}) MNPs. In addition, for cobalt ferrite nanoparticles to be used within the body they must be rendered biocompatible through surface ligand exchange processes in order to avoid being targeted by the body’s autodefense system. Therefore, different ligands were experimented with to determine an optimal coating for usage in the body. 

G70.00069: Establishing Monomer vs. Aggregate Composition of SquaraineBased Organic Photovoltaics Using Atomic Force Microscopy Adriana Cruz, Catherine Ryczek, Zhila Hooshangi, Soumya Gupta, Christopher Collison, Kristen Burson Organic photovoltaics (OPV) offer exciting possibilities for energy production and in optimizing OPV devices, a greater understanding of the organic solar cells' morphology is needed. Structural order is thought to improve charge mobility and energy transfer. Here we present a method for determining the monomer vs. aggregate composition for squarainebased thin films using measurements of each film’s absorptivity, thickness, and area. Population can be measured through absorption measurement, provided that the extinction coefficient of the species in question (aggregate or monomer) and the path length for the light through the sample are known. Therefore the ability to measure populations depends on an accurate values for the film thickness, typically 50150 nm. We employ atomic force microscopy (AFM) to measure film thickness and assess two techniques for removing thinfilm material to establish accurate heights. Both techniques yield consistent height data and we discuss their merits. AFM measurements yield average thickness measurements for each type of film with an uncertainty under 17% and area measurements with an uncertainty under 3%. These low uncertainties are crucial as they allow for the monomer to aggregate population to be measured with a high level of precision. 

G70.00070: Development and Characterization of a Prototype Cosmic Microwave Background Calibration Target David Stilwell, David B Greene, David Chuss, Martin DeGeorge, Karwan Rostem, Edward J Wollack The capability to construct devices that have low reflectance (and high absorptivity) of electromagnetic radiation at long wavelengths has many potential applications ranging from radar evasion to EMI control to calibration of sensitive detectors for cosmology. In cosmology, characterization of the spectrum and polarization of the cosmic microwave background, the afterglow of the Big Bang, requires measurements that are accurate to one part in 10^{7}. We describe the fabrication of a prototype cosmic microwave background calibration target that consists of an array of 169 cones, each constructed of loaded epoxy that is molded around an aluminum core for mechanical attachment and thermal stability. By testing the target over a range of frequencies, we achieved a reflectance of 50 dB. These processes were developed as a key technology to support a future NASA space mission to measure the spectrum and polarization of the cosmic microwave background to probe the physics of the early universe. 

G70.00071: Schottky diode based on large area CVDgrown WSe_{2} Ahmad Matar Abed, Anamaris Melendez, Nicholas Pinto, Idalia Ramos Twodimensional transition metal dichalcogenides have attracted great attention due to their unique optoelectronic applications. Of these, tungsten diselenide (WSe_{2}) is a semiconductor with a trigonal structure, and a small bandgap ~1.6eV. Here we report electronic transport measurements of CVDgrown WSe_{2} configured as a Schottky diode. To prepare the device, the WSe_{2} film was transferred onto an ndoped Si/SiO_{2} wafer with prepatterned gold electrodes over the oxide surface. The diode parameters were analyzed using the standard thermionic emission model of a Schottky junction. Results obtained at room temperature include a forward turnon voltage of ~0.46 V, ON to OFF current ratio at ± 1 V of ~1100, barrier height of 0.41 eV and an ideality parameter of n~1.3. The device was tested as a halfwave rectifier showing a rectification ratio of 1150 with an output/input voltage ratio of 46.3%. Efforts to investigate the temperaturedependent transport mechanisms of the device will also be presented. 

G70.00072: A Novel Application of Focused Ultrasound for the Treatment of Port Wine Stain Birthmarks Kristen Doucette, John O'Malley, Phillip Jason White Annually, 0.30.5 % of the population is born with a Port Wine Stain (PWS) birthmark. A PWS is a capillary malformation that results in a visible, localized vascular lesion. This lesion is characterized by an increased number of dilated capillaries that give the PWS its red discoloration. The gold standard of PWS treatment is photothermolysis with Pulsed Dye Laser (PDL) emitting at a wavelength of 595 nm. The PDL selectively damages the PWS by using the wavelength at which hemoglobin absorbs light to thermally destroy capillaries. Due to limitations of PDL penetration depth, the deepest capillaries are often left untreated. This can form seed locations where new capillaries can develop, causing the PWS to darken in color over time. 

G70.00073: ABSTRACT WITHDRAWN


G70.00074: Optimization oof nanopillar dimensions for maximum light absorption Evangeline Beeching Conductive organic polymers such as Poly(3hexylthiophene2,5diyl) P3HT, and Poly{2,2′[(2,5bis(2hexyldecyl)3,6dioxo2,3,5,6 tetrahydropyrrolo[3,4c ]pyrrole1,4diyl)dithiophene] 5,5′diylaltthiophen2,5diyl} PDPP3T are being studied for use in solar cells due to their flexibility, cost effectiveness, and low environmental impact when compared to traditional inorganic thin films. However, these organic polymers do not yet have the same efficiency as their inorganic counterparts and are not being largely produced. It is established that replacing thin films with nanopillars enhances the light absorption when the diameter of the nanopillar is less than that of the wavelength of light. We fabricate P3HT nanopillars with approximate diameters of 76 nm using a porous alumina template. We will be optimizing the dimensions (diameter, height and interval) of the nanopillars for maximum light absorption of wavelengths between 400700 nm. The dimensions of the pores can be controlled by varying the timing of the pore widening process which in turn changes the dimensions of the nanopillars. We aim to fabricate nanopillars of various polymers and compare the intensity of absorption of their thin films with the nanopillars using UVVis spectroscopy. 

G70.00075: Exploring twodimensional devices William Shannon, Byron Greenlee, Joel ToledoUrena, Joseph Murphy, Jennifer T Heath Twodimensional materials and devices are opening up a wide range of possibilities for both fundamental and applied research, yet are accessible to the undergraduate lab. We have built a system to layer twodimensional exfoliated materials into stacks, opening up the possibility of creating a wide range of device structures. This system has been tested by creating twisted bilayer graphene structures, which are known to exhibit Moiré patterns and have electrical properties that vary with twist angle. These bilayers and other simple field effect devices are being studied further with Atomic Force Microscopy, Kelvin Probe Force Microscopy, and bulk electrical measurements to understand electric field screening and potential barriers. Twodimensional devices have big potential for the future of electronics, and understanding their behavior is an important first step. 

G70.00076: Treatment of Pancreatic Cancer Cells with SWCNTPolymer Nanocomplexes as Drug Carriers Cristina Rosas, Juan Montemayor, Paul A Withey Recent studies show an alternative treatment for cancer that uses singlewalled carbon nanotubes (SWCNTs) as drug delivery agents because of their ability to cross cell membranes easily. SWCNTs were dispersed with polyvinyl alcohol (PVA) and Pluronic biocompatible polymers before introducing anticancer drugs in the CNTs. Camptothecin (CPT) and Doxorubicin, the anticancer drugs used, formed noncovalent CNTpolymerdrug conjugates in aqueous solution when attached to CNTs with a biocompatible polymer. Nearinfrared (NIR) fluorescence emission peaks of (7,5) and (7,6) CNTs verified the polymeric dispersion of SWCNTs by both polymers. Pancreatic cancer cells that came from PaCa2, a pancreatic cell line, were exposed to various concentrations of PVA and CPT with varying SWCNTs to examine the effectiveness of these complexes. The number of viable cells were observed to also determine how effective the treatment was. Preliminary results demonstrate SWCNTs serve as good drug delivery agents and can help increase the effectiveness of anticancer drug on the cancer cells. 

G70.00077: Modeling Ultracold Atomic Clouds Confined by Atomchip Magnetic Traps Xiaole Jiang, Nathan Lundblad NASA’s Cold Atom Laboratory (CAL) conducts experiments on ultracold atoms in orbital microgravity using microfabricated electromagnets (atom chips). We report on the creation of a generalized model, applicable to CAL experiments, for calculating the properties of magnetic traps associated with BoseEinstein condensates (BECs). While atomchip BEC machines offer relative simplicity and compactness, such modeling tools are necessary to elucidate certain features (such as the aspect ratio of the trapped ultracold cloud) which might not be intuitive to typical users of the CAL facility. The model (written in Mathematica) is designed such that its interface and setting is generalized, so that users with different priorities or experimental goals, or who are unfamiliar with the code, could use it. We plan to use this model to inform the creation of radiofrequencydressed magnetic traps and bubblegeometry BECs aboard CAL. 

G70.00078: Barrier Height Measurement of Cadmium Telluride (CdTe) Solar Cells Patrick Milan, Jose Peralta, Madison Guerrero, Prof Weining Wang Among the thin film generation, the Cadmium Telluride (CdTe) solar cell is favored for research because it has a low cost and a relatively high efficiency (22.1% in 2016). However, its efficiency is still lower than the theoretical limit. One major problem is at the backcontact junction. Since CdTe solar cells have a high electron affinity (about 4.5 eV), typical back contacts such as metals fail to create good ohmic contacts and as a result a Schottky barrier is formed at the backcontact junction. The Schottky barrier affects charge carrier collections and lowers the efficiency of the cell. 

G70.00079: The Effect of Contact Material on Perovskite Solar Cell Efficiency Madison Guerrero, Patrick Milan, Jose Peralta, Hongkun Cai, Weining Wang Perovskite solar cells have made tremendous improvements since it was first reported on 2009. Its efficiency has increased from 3% to an outstanding 22.1% in less than eight years. Due to its rapid increase in efficiencies and low cost fabrication process, the perovskite solar cell technology was named as one of the biggest scientific breakthroughs in the year of 2013 by Science. In the Perovskite solar cell structure, poly(3,4ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) is usually used on top of ITO as the conducting electrode. 

G70.00080: Image analysis of microgravity BoseEinstein condensation Maxwell Gold, Nathan Lundblad With the recent production of BoseEinstein condensates aboard the International Space Station using NASA’s Cold Atom Laboratory (CAL), research is underway focusing on new condensate geometries made available by a microgravity environment. We report fitting analysis and trap frequency characterization of imaging data from condensates in both conventional and rfdressed magnetic potentials. This information will be used for calibration and design of future experiments with CAL examining ellipsoidal shell condensate geometries. 

G70.00081: Modular Smart Home: A proof of concept, by Wyatt Vigilante Wyatt Vigilante Current smart home systems can cost upwards of $15,000. This project seeks to create a similar system for $500 or less. A modular smart home contains a network of smart devices that work together to perform homely functions such as turning on lights or adjusting temperature in a room if movement is detected. To bring costs down an Arduino Mega 2560 microcontroller will be connected to the sensors and output the incoming data to the Raspberry PI which will act as an interface for the user. This system also avoids the use of an internet connection to make it more difficult for potential hacking of the system. To validate the effectiveness of the modular smart home system, devices such as RFID card access, light switches, temperature sensors, fans, sonar sensors, RGB lighting, and motion sensors will be implemented into a 1/32 scale model of a 2bedroom house. Once the system has been implemented into the scale house, estimates of cost efficency in the modular smart home will be taken to compare against the $15,000 standard smart home to prove the effectiveness of the system. 

G70.00082: Exploring the Structural Transformation of Zirconia Films Mark Lewis, Frank C Peiris, Santosh Shaw, Ludovico Cademartiri Using a combination of experimental techniques, including Raman spectroscopy, Fourier Transform IR spectroscopy (FTIR), Xray diffraction, atomic force microscopy (AFM) and ellipsometry, the structural transformation of a series of zirconia films were investigated. The zirconia nanoparticles (diameter of around ~4 nm) were first treated with ligands (either oleic acid or trioctylphosphine oxide), and then were spincoated onto Si substrates. The asgrown samples were then exposed to an oxygenplasma, and were subsequently calcined at various temperatures (300° C  900° C). Raman, FTIR and Xray diffraction show that the zirconia films transform from amorphous to tetragonal and monoclinic phases as a function of the calcined temperature. Using an effective medium approximation to model the ellipsometry spectra, the porosities of the zirconia films were recovered. While the porosity values decrease for both types of samples, the porosity seems to decrease faster for the samples that were capped with oleic acid. The RMS values determined from AFM measurements optimized the ellipsometry models, which included a surfaceroughness layer to fit the experimental spectra. 

G70.00083: Single Photons for a Modular Ion Trap Quantum Network Sophia Scarano, Martin Lichtman, Clayton Crocker, Ksenia Sosnova, Allison Carter, Christopher Roy Monroe Trapped atomic ions of different species are an ideal candidate for a modular quantum computing network partially due to low crosstalk between memory and communication qubits. A dual species Yb^{+}/Ba^{+} ion trap is used to create entanglement between memory spin qubits and photonic qubits. The flying qubits are emitted via the 6S_{1/2} ↔ 6P_{1/2} transition in ^{138}Ba^{+}. It is advantageous to excite the atom on the 5D_{3/2} ↔ 6P_{1/2} transition at 650 nm, while still collecting 493 nm photons. This removes the excitation light as a source of noise and reduces double excitation errors. Most significantly, the D ↔ P transition allows us to use a slower excitation, such that instead of requiring a picosecond pulsed laser, we can gate a CW laser using AO modulators. We demonstrate a single photon source for quantum networking based on a trapped barium ion subject to pulsed excitation with a secondorder coherence of g^{(2)}(0) = (8.1 ± 2.3) × 10^{5} without background subtraction, a stateoftheart result for replicable single photon sources. 

G70.00084: Modeling of Cytoskeletal Filaments in C17.2 Cells using ImageJ Julia Hutsko, Jay Magers, Sabrina Jedlicka, Swetha Chandrasekar, Slava V. Rotkin, Lisa Schneider, Massooma Pirbhai Cytoskeletal filaments, such as actin, and nestin assist in sustaining many cellular function, including: differentiation, motility, cell shape, force generation, etc. Studies on how actin reorganizes can give us insights into how external stimuli affect cellular processes. The external stimuli chosen for this research was carbon nanotubes, which are single atom carbon sheets rolled into cylinders. For this study, neural stem cells, specifically C17.2 cells, were the focus. The goal is to observe how the distribution of actin is altered in the presence of carbon nanotubes. Over the last semester, I collected a catalog of data on the volume of actin in both treated and untreated C17.2 cells. Images of actin were captured using confocal microscopy. ImageJ then characterized the volume of the filaments at each level in the neural stem cells and quantified the actin distribution using thresholding techniques. The results, I obtained from comparing my data, showed how carbon nanotubes impact the distribution of actin throughout the cell. 

G70.00085: Application of a Retired Burst Gravitational Wave Data Analysis Method to Investigate the Origin of the Blip Glitch Sarah Choate, Amber L Stuver The Laser Interferometer GravitationalWave Observatory (LIGO) is a collaboration with the goal to observe and study events that create gravitational waves detectable on Earth. During the process of data acquisition, glitches in the data can occur as a result of the observation of transient noise. One class of these glitches that occurs in burst data analysis is the blip glitch, which results in an almost identical signal to that of a gravitational wave detection and has an unknown origin. SLOPE is a data analysis method originally used for gravitational wave detection. This research has redeveloped SLOPE for the purpose of investigating glitches and has readied the algorithm to be applied to auxiliary channels to search for glitches. Results presented includes operating parameters for which SLOPE can be effectively run. 

G70.00086: ABSTRACT WITHDRAWN


G70.00087: Properties of PVDF Films Blended with Zwitterionic Copolymers Miriam Salcedo, Nelaka Dilshan Govinna, Samuel Lounder, Ayse Asatekin, Peggy Cebe Poly(vinylidene fluoride), PVDF, is a semicrystalline polymer used as a membrane for filtration and separation applications. Its properties can be enhanced by blending together with zwitterionic copolymers which alter the hydrophobicity. In this work, we study the structure and electrical properties of PVDF blended with the random copolymer poly(methylmethacrylatersulfobetaine2vinylpyridine). Solutions in dimethylacetamide/ acetone are prepared by varying the concentration of the blend components. Doctorblading is used to make films of uniform thickness for further investigation by wide angle Xray scattering, calorimetry, scanning electron microscopy, and dielectric relaxation spectroscopy. The crystalline and glassy structure of these films is determined by the manner in which the solvent is removed from the film, either by slow and continuous evaporation of the solvent, or rapid solvent removal by water immersion. These casting methods create different pore size and distribution which affect the structure and dielectric properties of the films. 

G70.00088: SuperResolution Patterns in Quantum Dots Hamid Jalili, Thomas Danza, Richard Mouradian, Sean James Bentley In this research, quantum dots and other materials were measured for their ability to absorb nonlinearly. Using the second harmonic of a nanosecond Nd: YAG laser an interference pattern was etched onto a quantum nanoparticle thinfilm sample and a reference sample which were then compared against linear and nonlinear absorption. After one pattern was formed, a second pattern was interlaced with the first by introducing a phase shift into one arm of the interferometer. Due to the nonlinear nature of the absorption, this allows the formation of a pattern with twice the resolution possible with linear techniques. While the visibility of the combined pattern is reduced as compared to simple interference, it is still sufficiently high for many applications. 

G70.00089: Observations of Dislocation Etch Pits in SmB6 Shriya Sinha, Alexa Rakoski, Cagliyan Kurdak, Priscila Rosa, Monica Ciomaga Hatnean, Geetha Balakrishnan, Boyoun Kang, Myungsuk Song, Beongki Cho Samarium hexaboride (SmB_{6}) is a strongly correlated topological insulator, showing insulating behavior from 440 K and a conduction plateau below 4 K due to the topological state. Recent transport results on the bulk have demonstrated that SmB_{6} is not sensitive to point defects but extended defects such as onedimensional dislocations may still be present. Such dislocations may provide an additional current path beside the topologically protected surface state. The one dimensional dislocations must terminate on the surface and can be identified by the use of proper chemical etching. In order to characterize the bulk defects in SmB_{6}, we developed an etching technique using equal parts sulfuric acid and nitric acid. Using this etchant we found etch pits in the shape of inverted pyramids aligned with the crystalline axis, which are expected to indicate dislocations. In aluminum flux grown samples, dislocation etch pit densities range from 2x10^{6} to 9x10^{6} cm^{2}. A comparison of flux grown samples and floating zone grown samples will be presented. 

G70.00090: A demonstration of quantum key distribution with single photons for the undergraduate laboratory Baibhav Sharma, Enrique Jose Galvez, Aayam Bista The goal of this work was to create a laboratory experiment feasible in an undergraduate setting that demonstrates quantum key distribution and security attacks on quantum key distribution using single photons. The basic principle behind this experiment is that when a measurement is made on a quantum state, it modifies the information it conveys. This principle has been extended to quantum secure communications and is a teaching moment for physicists, computer scientists and engineers alike. We mimicked Eve or the eavesdropper by using an intercept and resend method, which include using an interferometer and a quartz plate. We used polarization entangled photons produced by parametric downconversion. 

G70.00091: ABSTRACT WITHDRAWN


G70.00092: LithographyFree Confinement of 2D Materials Using Precision Laser Ablation Ethan Richman, Yanpei Deng, Cameron Miller, Zach Wiener, LiHeng Chang, Vishrut Tiwari, Christopher LaFratta, Paul CaddenZimansky The everexpanding array of twodimensional materials and heterostructures susceptible to alteration in oxygen environments motivates the search for lateral confinement techniques outside conventional lithographic and etching methods. Laser ablation of such materials using a femtosecond pulsed Ti:Sapphire laser and programmable xy stage is a singlestep process that can in principle be used as a flexible tool for device processing. However, scanning probe analysis of submicron graphene ribbons fabricated with this technique reveals considerable defect accumulation under ambient condition. We show that such defects are largely alleviated by the simple change in the ablation environment from air to water. 

G70.00093: Scanning Electron Microscopy – New Approaches in Imaging Biological Specimens Indrajith Senevirathne, Sylviana Hanna Scanning Electron Microscopy (SEM) of biological systems has a long and illustrious history. However due to the inherent complexities of biological hard and soft matter interaction with electrons and with the imaging system, one must overcome certain hurdles. We have attempted to optimize typical biological SEM sample preparation such as critical point drying, fixing of microbes via Osmium Tetroxide and other techniques in this investigation. In the study, we have also focused on the effect of the conductive coating (magnetron sputter deposited) on the specimen. The study concluded with stereoscopic 3D imaging of the specimen acquired by the SEM Secondary Electron and Backscattered Electron Detectors. We will discuss the results and compare them with the current literature. 

G70.00094: Modulating the Magnetism of LaCoO_{3} Thin Films Via Strain Engineering Ronaldo Rodriguez, Toyanath Joshi, David Lederman LaCoO_{3} thin films grown on SrTiO_{3} (100) single crystals exhibit an anomalous ferromagnetic transition at T_{c}= 87 K. This material is normally not ferromagnetic and the mechanism of the transition is not well understood, although the OCoO bond angle is believed to play a crucial role. It is shown that the compound is not ferromagnetic when grown on LaAlO_{3}. Further strain, which presumably alters the bonding angle, can be achieved by growing LaCoO_{3} on large angle miscut SrTiO_{3} substrates in a layerbylayer growth mode with the angle of miscut being α ~10°. Films are grown using pulsed laser deposition employing a a 248nm KrF excimer laser to ablate a stoichiometric LaCoO_{3} target. The growth is studied via insitu reflection high energy electron diffraction (RHEED), which can detect layerbylayer growth when the RHEED intensity oscillates as a function of growth time. Crystallinity and topography are measured using Xray diffraction and atomic force microscopy, respectively, and magnetometry as a function of temperature and magnetic field is measured using a superconducting quantum interference device (SQUID) magnetometer. 

G70.00095: PHYSICS EDUCATION


G70.00096: An advanced laboratory course based on the construction and modeling of a magnetooptic atom trap Lee E Harrell, Mary Clare Cassidy, Kirk A Ingold, David O Kashinski, Corey S Gerving Undergraduate physics labs often entail the collection of data using an apparatus that is set up and sometimes even fully adjusted before the students arrive. Various physical phenomena and data analysis techniques can be explored with this approach; however, students are unlikely to develop the experimental design and construction skills that are necessary for conducting original research. We present a magnetooptical atom trap designed and constructed for use in an undergraduate lab class that is organized to address the shortcomings of the more traditional approach. While the basic design and necessary equipment are made available, the students are required to build a working atom trap starting from an empty optics table. Additionally, students must model and simulate the operation of the trap to determine the necessary operating parameters and their tolerances. The results of these simulations provide a basis for interpretation of data collected from the operating trap. 

G70.00097: WITHDRAWN ABSTRACT


G70.00098: Physics Education Research on Inexpensive ActiveLearning Lab Modules Zoe Mutton, Corinne Rywalt, Megan Varney, Nancy Burnham Active learning strategies, including hands on activities and lab work, have proved to be beneficial to student comprehension and success in physics classrooms. Despite this, many high school physics classrooms lack lab equipment necessary to supplement learning, mostly due to budget limitations and the high cost of traditional mechanics lab equipment. This project aims to design three modular, inexpensive, and demonstrative labs to enhance student knowledge in friction, conservation of energy, and torque. These labs, including a worksheet for students to complete, are designed to be easily implementable, take 2030 minutes to complete, and be cost effective. These labs were tested with high school teachers and students to show that they are easy for teachers to implement in their classrooms and that they are easy to understand and effectively demonstrate their respective learning objectives to students. The implementation of these modular labs in high school classrooms will aid learning by kinesthetically illustrating the topics taught in lectures, leading to better student comprehension and higher success rates in introductory mechanics. Furthermore, high schools that cannot afford traditional lab equipment now have the opportunity to provide mechanics lab work to students. 

G70.00099: Engaging and Sustainable High School Physics Lab Curriculum Using Smartphones Savannah Grunhard, Zainil Charania, ShengChiang Lee The purpose of our research was to develop an engaging and lowcost, hence sustainable physics lab curriculum for implementation in Bibb County, GA, public high schools. Each public high school in Bibb County receives $1000 per year for the whole science curriculum. This is barely enough to restock consumable items in chemistry and biology and leaves nothing for physics. The lack of sufficient funding for proper lab equipment and qualified teachers disadvantages students. We believe that this contributes to the low rate of Bibb County high school students taking at least one physics course before graduating (only half of the national average). 

G70.00100: How much science jargon can kids remember in 3 weeks Eduardo Velazquez Children who do not have food security are not in the right mind set to learn, but there are programs that take care of that during the school year. As a result, many children suffer from food insecurity over the summer while they are not in school. To help solve a part of this program, the Mexican American Unity Council (MAUC) provides these children with a summer camp that last 3 weeks during the weekdays from 9 am to 1pm. Each day of the camp brings a new activity and these activities follow a weekly theme. This year, the first week’s theme was science, the second week theme was super heroes and the final week had a cooking theme. During the period of this summer camp, I surveyed the children to see how much they liked each subject. I also asked them how much science they saw or recognized in each theme. The objective of each survey is to see if the children would retain scientific information after the summer camp, particularly, their science vocabulary, and to see if they can recognize science phenomenon in their everyday lives.This poster will discuss the findings and lessons learned for this past summer camp in an attempt to help us improve the children’s interest in science.The results of the surveys show some promising data for this first attempt. 

G70.00101: Designing Introductory Physics Experiments for the Visually Impaired Morganne Kendyll Bennett, Paul Quinn ``The only thing worse than being blind is having sight but no vision,” is a famous quote from Helen Keller. Teachers of students with visual impairments, must constantly look at the world from a different perspective, one without sight. For these educators, it becomes necessary to adapt the learning environment, making it more accessible to visually impaired students. This becomes more difficult in the STEM fields, particularly physics. This project redevelops some common introductory physics labs in a more tactile fashion, so that the same conclusions can be drawn without visual tools. This involved the design of various pieces of equipment such as a tactile graph board, making it possible for visually impaired students to experience the relationship between variables in the physical world. In this project, we were able to take topics, such as current and resistance, and make them more accessible to the visually impaired population. We discuss the various techniques and pieces of equipment designed to accomplish this goal. Also, the results of these experiments are discussed, after using the more tactile process in collecting and analyzing the physical data. 

G70.00102: Learning physics by experiment: IV. Kinematics Saami Shaibani The trajectory of a ball in sports settings provides extensive opportunities for students to see how principles from physics can be applied to a familiar activity. Advanced equations[1] in mechanics are employed in this research to design an investigation of the relationship between launch speed and launch angle under a variety of circumstances, such as launch height and distance from target. Students are not given access to these theoretical results because they are unduly cumbersome; instead, students identify launch outcomes solely on an empirical basis. Data from such laboratory experiments are high in quality even in the absence of any numerical context, and students report that they are not concerned about the latter because they enjoy the freedom of exploring without constraint. Other educational benefits include a relaxed learning environment and enthusiastic communication between students. Such advantages are further validation of the pedagogy that has been applied to multiple topics[27] with considerable success. 

G70.00103: Learning physics by experiment: V. Ambulation Saami Shaibani A multitude of devices associated with developing and maintaining fitness have been introduced in the past decade or so; examples include activity trackers and other wearable instruments, which have the capability of wireless communication for sharing data that they capture. Although the use of such equipment is becoming more widespread, favorable health outcomes (such as weight loss and improved cardiovascular function) have either been too low to be noticeable or have only a small impact[1,2]. The purpose of this study is to compare these devices with those based on much simpler technology (that typically costs an order of magnitude less) to determine to what extent, if any, the considerably greater expense of the former provides commensurately greater benefits than the latter. Experimental procedure is limited to be appropriate for students at the introductory level. Parameters of interest include design, temporal, geometrical, physiological, environmental and human factors. The research conducted here not only expands the number of projects having a similar educational value[3], but also extends the variety. 

G70.00104: Learning physics by experiment: VI. Angular momentum Saami Shaibani A critical piece of medical equipment for use in trauma environments has an inherent, and yet necessary, mechanical instability in its design. This instability can pose danger to operators of the equipment if certain safety measures are not observed; however, it is not always possible to implement every precaution in the highrisk settings usually associated with lifethreatening emergencies. The author has direct experience of how the subject equipment is employed during prehospital care by first responders, including being present when the equipment caused injury even before it was needed. Application of fundamental principles in this research enables the dynamic properties of the equipment to be calculated with basic calculus and algebra, with the latter being particularly extensive. The behavior of the equipment under recommended procedures is then analyzed to produce a baseline performance, against which the response of the equipment in adverse circumstances is compared. As with other studies conducted throughout this innovative series[1], powerful techniques for superior student understanding are developed from the real world in a manner that transcends the most creative examples in standard textbooks. 

G70.00105: The Physics of Ice Cream – An Interdisciplinary Course Joseph Trout At Stockton University an interdisciplinary course was developed by a physicist, chemist, and food scientist, which studies the science of ice cream. Ice Cream can be an excellent vehicle for teaching concepts in physics and chemistry. For example the process of the phase change from a liquid to a solid of water in the ice cream mix is an interesting comparison to the process which occurs in pure water. The course is composed of a lecture portion and a lab portion. Topics covered include Newtonian dynamics, fluid mechanics, and thermodynamics. This presentation briefly describes the course and provides a preliminary assessment of the course. 

G70.00106: Initiating the Transition to Studio Physics in a Large Public University: A Case Study Diego Valente, Niraj Ghimire, Jason Hancock The University of Connecticut is currently in the initial stages of an extensive reform to several of its introductory physics courses seeking to shift away from the traditional framework of isolated lectures and laboratory sessions in favor of a studiobased instructional model blending lectures, problemsolving tutorial sessions and handson experimental activities. When completed, we expect this largescale pedagogical reform spanning a total of 3 introductory sequences and 6 courses to impact approximately 2,000 students each year. In this work we discuss details of our current pilot program preparing us to make the transition to studiobased instruction in our larger introductory courses, as well as some of the challenges we face. We also present preliminary data on student learning comparing normalized gains on concept inventory assessments administered in our pilot courses to similar data collected in previous implementations of these courses taught in a traditional format. 

G70.00107: Incorporating NonWestern Contributions Into the Intro Physics Curriculum Brianna Billingsley, Cory Christenson If you look through any physics textbook you will encounter canonical names such as Newton and Galileo. While their contributions are indeed significant, presenting the history of physics solely in terms of these western scholars hides a much deeper and complex history that is not often taught. Here we will discuss how to incorporate contributions from Chinese and Arab civilizations. These concepts can be introduced to students through labs, homeworks, and discussion questions. A broader and more culturally diverse scientific history can engage student interest, teach them about how science actually happens, help them to appreciate the value of diversity. 

G70.00108: SelfDriving ArduinoBased Toy Cars for Introductory Physics Labs Matt Prezioso, Cory Christenson This poster will explain how computer operated robotic cars can be implemented in college physics lab classes to introduce students to programming while also teaching them about kinematics. Arduniobased toy cars were built that can respond to light and distance stimuli, simulating the effect of traffic lights. The students are provided a basic code and asked to modify it to control the car's motion, and compare the observed motion to the theoretical kinematics equations. This combines the core physics concepts with realworld examples and useful programming skills. These cars can also be used to study traffic flow and energy use in transportation grids. 

G70.00109: A ShortTerm Physics Study Abroad Experience for General Education Student Davon W Ferrara Students looking for general education science courses often try to avoid those in physics. However, there are many concepts in physics that students ultimately enjoy learning about once in the course. One way to motivate students to take a conceptual physics course is to teach it while traveling through Italy on a shortterm study abroad program. The conceptual laboratory science course described here has been taught four times since 2014 during “Maymester”, a threeweek term between spring and summer semesters. The course uses the Galilean scientific revolutions during the Italian Renaissance as a starting point to understanding some of the major developments from classical mechanics to modern physics and the interactions between science and culture, including with respect to religion. Although this shortterm study abroad course is in continual development, with changes to the itinerary and pedagogy each year, this presentation will give an overview of the trip, examples of laboratory experiments done while abroad, and a discussion of ways to keep nonscience majors engaged in learning physics throughout the trip. 

G70.00110: Common Student Misconceptions in Physics Classes: Mechanics Kyle Bautista, Carolina C. Ilie Physics is an important and amazing field of study. However, Physics can be a complicated subject for some students. There are several different topics and areas of physics where students seem to develop or have previously acquired misconceptions. It is possible for these common misconceptions to be found by taking a closer look at what a students’ rational is when they are answering a question. To do this, a Physics survey was created based on several topics in the introductory mechanics unit covered in a collegelevel physics course. Participants were asked to answer ten questions covering a range of topics including graphs of motion, force, and mechanical energy. Answers to the survey were multiple choice along with a brief explanation with each answer to better identify the cognitive process of participants and diminish guessing. The surveys were collected and all responses were analyzed for any common errors. Using the data collected, we identified the physics misconceptions. We created and implemented new pedagogical strategies aimed to clarify the physics concepts. Some say Physics can be a challenging subject to learn, but with the appropriate studentcentered classroom techniques, it is possible for anyone to not only succeed, but find a greater passion for the field. 

G70.00111: A Useful EndofSemester Physics Course Assessment Survey Norma Chase This scantronbased survey examines the teacherlearner collaboration. It includes questions which probe student preparedness, behaviors, attitudes, and expectations – as well as questions addressing key measures of excellence in teaching and course structure. We find that the most valuable information is revealed when survey responses are displayed at the level of individual students  for it is there that we find data which we can use to improve our guidance of student learning and cognitive development. Bar graphs are used to look for any interdependence between responses to pairs of survey questions. By thus examining the data in its entirety, we obtain insights which might inform future students, as well as faculty and administrators. 

G70.00112: A training course design for developing a student into an academic researcher Bing Shen For the undergraduate student who want to enter the academic in the future, the basic scientific training is important and necessary. However, this kind of training is not like the regular course which need design in a different way. In this talk, we study the students from the condensed matter physics. By interviewing the students, teachers and researchers, we found the experiment technique and strategy changing are important to the developing a student into an academic researcher. 

G70.00113: Characterizing HandMade Planar Inductor Components in the Series RLC Circuit Daniel CansecoChavez, Stephen A Tsui In the introductory physics curriculum, students are taught induction and inductance by examining the behavior of the currentcarrying coil. As electronic devices approach the nanoscale, one might ask a student how would it be possible to fit an inductor onto an electronic chip. A commercial microelectronics solution is the planar spiral inductor, which are conductive thin film patterns deposited on substrates especially used for high frequency applications. Although synthesizing a thin film is beyond the reach of most classrooms, the principles and advantages of a thin film inductor can be taught using very affordable copper tape. An instructional laboratory activity based on this design introduces students to inductors using a geometry not covered in the introductory text and also offers them insight into the solutions necessary to build devices at the micro and nanoscale, which would especially be useful to careers in engineering and applied physics. In this work, we demonstrate the construction of macroscale planar spiral inductors using commercially available copper tape and compare their behavior to an offtheshelf inductor. 

G70.00114: PHYSICS OUTREACH AND ENGAGING THE PUBLIC


G70.00115: Paperbased controllable illumination for multimode microscopy Simren Kaur, Ryan J. McGorty A paperbased microscope makes for a rugged and versatile solution to bringing science and science education to a variety of settings including those that are resourcescarce. This has been well demonstrated by the Foldscope project. Here, we describe an extension to that idea. We designed a paperbased method to control the sample illumination in a portable microscope. Controlling the illumination of the sample allows us to employ a variety of microscope imaging modalities including brightfield, darkfield and phase contrast. With this instrument, students can explore those different techniques. Additionally, it can be used to perform advanced imaging, including quantitative phase imaging, in the field, away from advanced and costly instrumentation. 

G70.00116: AI framework to solve sustainability issue based on social and political dynamics Deeder Aurongzeb Sustainable product developement requires long term model building that may require social dynamics input. Scaling up temporal causality analysis to very large scale state spaces and extending the frame work to handle large relational data is a critical undertake to create a large scale dynamic model. We extend crosssepctral model by C Granger,, J, of Econometric Soc, V37,N3,424, in light of modern casual models and provide a AI frame work on how AI can provide sustaibility models in various aspect of social and political conditions using temporal logic. 

G70.00117: HISTORY OF PHYSICS


G70.00118: Bibliographic Visualizations of Early Work in Neutron Diffraction Matthew Marsteller The literature of neutron diffraction was explored using Web of Science data and VOSviewer for data visualization. The timespan covered was from the advent of the topic through 1955 when Clifford Shull left Oak Ridge. The search query in Web of Science allowed for either "neutron diffraction" or "neutron scattering" to appear in the resulting records. Visualizations will include networks of coauthors with numbers of documents produced. Coauthor groups readily appear in the visualization and allow for identification of important research teams. Shull and Ernest Wollan appear in one cluster. George Bacon of AERE, D.G Hurst and D.G Henshaw of Chalk River are easily visible as well. Other visualizations include citation networks of documents, authors or sources. 

G70.00119: EARLY CAREER SCIENTISTS


G70.00120: Density Functional Theory Calculations of Stability and Absorption Spectra of Au_{8} Conjugated Complexes with Met and Trp Amino Acids and TrpMet Dipeptide Marwa Abdalmoneam Interactions of Au_{8} (D_{4h}) gold cluster with the functional groups of the amino acids; LMethionine (Met) and LTryptophan (Trp), and the dipeptide LTryptophylLMethionine (TrpMet), in their zwitterionic forms and in presence of solvent have been investigated using the density functional theory (DFT). Specifically, the binding energies and UltravioletVisible (UVVis) absorption spectra of the bioconjugated complexes of Au_{8}Met, Au_{8}Trp, and Au_{8}TrpMet have been analyzed. Our calculations show that; the pristine Au_{8} (D_{4h}) cluster has strong absorption spectrum in the nearultraviolet range, in agreement with the literature. The optical activity of the pristine cluster is the major influencing factor on the absorption spectra of the studied bioconjugated complexes, but the spectra of the complexes carry sufficient remarks that allow them to be distinguished from that of the pristine cluster. The interactions of Au_{8} with each specific functional group (either indole or thiol ether) led to very similar absorption spectra whether this group existed in a mono or in a dipeptide amino acid. 

G70.00121: PUBLIC POLICY


G70.00122: Research Integrity, the Responsible Conduct of Research, and Plagiarism Analysis Aaron Manka Among its duties, the National Science Foundation (NSF) Office of Inspector General (OIG) 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 also handle allegations conflict of interests and violations of the confidentiality of NSF’s merit review to ensure the integrity of that process. We completed a review of how grantees implemented NSF’s requirement to provide responsible conduct of research training to undergraduate students, graduate students, and postdoctoral researchers. We are currently reviewing our plagiarism cases of the past decade to accumulate data and potentially identify institutional and NSF strategies for preventing and reducing plagiarism. I will briefly discuss these topics and present our results. 

G70.00123: Determining the Asymptotic Expansion of Prolate SpinWeighted Spheroidal Eigenvalues Daniel Vickers, Gregory B Cook SpinWeighted Spheroidal Harmonics (SWSHs) are a complete orthonormal basis of tensors on the surface of spheroids. While SWSHs are used in many fields of physics for modeling, this research is focused on their application to describing the normal modes of transmission on the surface of black holes in the Kerr Geometry. Much is known for the oblate case of SWSHs; however, the asymptotic behavior of the prolate case has yet to be well described. In this work, the prolate SWSHs problem was numerically solved, which was used to create a power series approximation for their eigenvalues. 

G70.00124: WITHDRAWN ABSTRACT


G70.00125: GRADUATE STUDENT AFFAIRS


G70.00126: Deific Naturalism: A Paradigm Shift from Matter to Consciousness as the Basis of Reality Consistent with all the Scientific Evidence Amy Lang “Science has to have a metaphysical framework to operate with confidence.”(Beyond Matter, Trigg) The prevailing scientific philosophy of naturalism assumes only physical causes, excluding any spiritual cause (God) to explain the inherent order of the universe evidenced by the laws of physics. This philosophy conflicts with surveys that show 51% of scientists believe in God or a higher power, with younger scientists at 66%. A paradigm shift to a metaphysical basis would explain this order. Physicists such as Planck have argued that quantum physics infers an observerdependent reality based in consciousness, not matter. Deific naturalism, as defined by Mary Baker Eddy with her discovery of Christian Science in 1866, defines God as the universal Principle of good which orders the material universe and to which all consciousness, since matter is a mental construct, is steadily yielding. Deific naturalism is also consistent with the growing body of documented evidence anomalous to naturalism and is verified by over 83,000 archived Christian Science healings (many medically documented) where the metaphysical method of prayer applies a spiritual cause to universally and repeatedly restore health and order, and explains Biblical miracles as divinely natural scientific demonstrations. 

G70.00127: SelectiveJet Electrochemical Processing for LowCost Additive Manufacturing of Metallic Components at RoomTemperature. Wael Othman, Omar Almelhi, Lütfiye Y. Ozer, Marco Stefancich, Matteo Chiesa SelectiveJet Electrochemical (SJE) processing has emerged as a novel approach for manufacturing metallic components with a lower cost in comparison with other conventional techniques. In addition, this technique allows metal processing at room temperature, which is considered a benefit as it reduces the need for expensive vacuums and temperatureregulating setups. Basically, SJE performs reduction of metal ions from one electrode and gives it back at the other electrode which is oppositely charged. One of the key characteristics is the capability of adding or subtracting material simply by reversing the polarity applied during the process, which helps in optimizing the AM process. One of the remaining drawbacks of this technique is the slow deposition rate that needs to be enhanced to achieve fully the promises of SJE. In this work, both deposition and etching of copper were monitored by using various polymerprinted nozzles diameters, along with varying current densities and process time. More specifically, relations of the dimensions, density and electrical conductivity of the deposited/etched materials to the mentioned parameters are reported that provide the critical parameter space to be optimized in order to achieve a speedy deposition and obtain the desired density. 

G70.00128: CLIMATE PHYSICS


G70.00129: FeCobased Ferrofluid for ELF Transmitter Applications Bryan Augstein, William Zimmerman, Naveen Reddy Kadasala, Stephen Blama, Mary Sajini Devadas, Vera Smolyaninova Developing compact and efficient extremely low frequency (ELF) transmitter antennas remains a challenge. A rotating magnetic dipole can be used for this application. In our approach we employ magnetic fluid, where suspended single domain nanoparticles act as rotating magnetic moments. The role of particle size and composition needed for optimal performance will be discussed. The FeCo nanoparticles were fabricated by wet chemical synthesis. Static magnetization and AC performance were measured. The role of nanoparticle concentration, type of superparamagnetic behavior, and AC permeability of FeCo magnetic fluid will be discussed. 

G70.00130: A preliminary investigation of large shift in transition temperature (Tc) in Gd_{5}Si_{3} nanoparticles Shivakumar Hunagund, Shane M Harstad, Shalabh Gupta, Vitalij K Pecharsky, Magundappa Hadimani Magnetic ordering temperatures in nanostructures depend on size. Curie temperature(Tc) of a bulk material where exchange interactions are comparable to thermal fluctuations tends to decrease in particles. The decrease of ordering temperature with size is described by the scaling theory of Fisher & Barber. 

G70.00131: ABSTRACT WITHDRAWN


G70.00132: MAGNETISM


G70.00133: Ferrimagnetism of TiAdsorbed Graphene Zhenzhen Qin, Min Feng, Xu Zuo Using the firstprinciples calculations, we investigate the magnetism of isolated Tiadsorbed graphene and the magnetic ground state of Ti adatoms at various concentrations. For isolated Ti adatom on graphene, we analyze the localization of magnetic impurity states and moment formation that can be understood in terms of hybridization between Cpz and Ti 4s3d orbitals. To examine the magnetic ground state of Ti adatoms, we construct graphene cells with Ti adatom at various concentrations and set up the magnetic configurations for a triangle lattice. It is found that a ferrimagnetic (FI) phase is the most stable in a wide range of Ti concentration by comparing the total energies of different magnetic states. In addition, the exchange integrals between the nearest neighbor and nextnearestneighbor Ti adatoms are calculated by applying a classical Heisenberg model. The prediction of a graphenebased FI metal monolayer will open the door to applications of spintronics, given that Ti obeys a 2D growth mechanism on graphene. 

G70.00134: Perpendicular magnetic anisotropy in onedimensional Rashba system under external electric fields: Firstprinciples study Zhenzhen Qin, Guangzhao Qin, Bin Shao, Xu Zuo External electric field (EEF) control of magnetization attracts much attention for potential applications in spintronics and is also a key challenge for designing quantum magnetic properties. Noticed, the role of EEF on magnetic properties of onedimensional (1D) Rashba system has not been explored, even lacking in theoretical. In this work, we comprehensively studied the effect of EEF (parallel or vertical) on the magnetic properties of our previous predicted 1D Rashba system—Gd adsorbed zigzag graphene nanoribbons (GdZGNRs) from firstprinciples study. Our calculations show that a moderate negative (positive) electric field stabilizes outofplane magnetization, where GdZGNR performs perpendicular magnetic anisotropy (PMA) whether the direction of the electric field is vertical or parallel, and intrinsic Rashba effect always exist. It is confirmed that the Rashba spin splitting and PMA are interrelated in 1D GdZGNR, in consistent with previous theoretical models. Furthermore, the (non)perturbed band structures under EEFs are analyzed to explore the underlying physics of MAE based on our proposed methods combined with traditional secondorder theory. Our results would provide a new insight into the mechanism of the magnetoelectric coupling at lowdimensional Rashba system. 

G70.00135: A Monte Carlo simulation for intermolecular interaction of 2D spincrossover compounds using the Isinglike model Saho Kajikawa, Azusa Muraoka Spincrossover (SCO) complexes show the SCO phenomenon: a remarkable bistability between diamagnetic low spin (LS) and paramagnetic high spin (HS) states depending on several parameters such as temperature, light, magnetic field, pressure, etc. In recent years, owing to the marked transformation of magnetic properties, colors, and molecular structures of transition metal complexes following the SCO phenomenon, SCO complexes have been attracting much attention for technological applications, e.g., highdensity information storage, display devices, and microsensors. The purpose of this study is to clarify the influence of intermolecular interaction on the phase transition. To evaluate the model and clarify intermolecular interaction on phase transition, we perform Monte Carlo simulation of 2D SCO complexes using Ising like model and calculate differences of magnetic susceptibility curves due to particle size and shape of SCO complex. 

G70.00136: Ice Sculpting: Neuromorphic Training of GeometricallyFrustrated Magnetic Metamaterials Kilian D Stenning, Alexander Vanstone, Jack C Gartside, Lesley Cohen, Will Branford Artificial spin ice (ASI) consists of ferromagnetic arrays populated by Isinglike nanopatterned macrospins. The array ‘microstate’ describes the magnetic orientations of all macrospins, with the ASI microstate manifold notable for its vast range of energeticallydegenerate states arising from geometric frustration. 

G70.00137: Magnetic anisotropy driven by enhanced spinorbital coupling of sp metal Bi on Au /Si(111) root3 surface Chong Li, Han Wang, Chunyao Niu, Fei Wang, Yu Jia, Zhenyu Zhang, Shengbai Zhang Realization of magnetic properties from nonmagnetic elements is an interesting issue recently. Using firstprinciples calculations based on DFT, we study of 1/3 monolayer Bicovered Au/Si(111) surface and find that such system can be magnetic remarkably. Our further analysis reveals that the large spinorbit coupling of Bi (p_{x}, p_{y}) multiorbitals at the Fermi level leads to an occupancy disparity between spin channels. And this occupancy disparity will break Krammers degeneracy, resulting in a nonmagnetic to significant ferromagnetic phase transition. Moreover, the relatively large and anisotropic Rashba splitting at the interface damps the inplane ferromagnetism, giving rise to an exceptionally large magnetic anisotropy energy up to 6.5 meV (with M_{z}/M_{x,y}~3). Our studies provide a potential candidate system for achieving an intrinsic quantum anomalous Hall effect with temperature up to 70 K. 

G70.00138: Electronic properties of chemically functionalized armchair GaN nanoribbons: A computational study Naresh Alaal, Iman Roqan Graphene synthesis has spurred immense progress in the study of lowdimensional materials, as they offer distinct properties when compared with their threedimensional bulk counterparts. Nanoribbons (NRs) are quasi onedimensional materials that exhibit interesting electronic properties based on their width and edge configurations. Edge functionalization is one of the techniques by which the electronic structure of NRs can be tuned. In this work, we employ firstprinciples spinpolarized calculations to study electronic and magnetic properties of oxygen and sulfurpassivated armchair GaN nanoribbons (AGaNNRs). Unlike bare AGaNNR, which is a nonmagnetic semiconductor, oxygenpassivated AGaNNR (OAGaNNR) displays magnetic behavior with a magnetic moment of 1 µB, as its band structure splits into spinup and spindown channels. Such behavior is caused by additional states that arise from the nonbonding electrons of the edge oxygen atoms. On the other hand, the sulfurpassivated AGaNNR (SAGaNNR) exhibits semiconducting properties and has a reduced band gap relative to its bare counterpart. Thus, we will discuss the physical mechanism that leads O and SAGaNNRs to be good candidates for optoelectronic and spintronic device applications. 

G70.00139: Longitudinal Resonance for Thin Film Ferromagnets with Random Anisotropy Wayne M Saslow, Chen Sun At the microscopic level, individual spins in ferromagnets with random anisotropy tip transversely with distinct local angles relative to the magnetization Μ. When driven by an rf field along the equilibrium M_{0}, which changes dΜ = Μ_{0 ‘ }dM, the transverse tippings rotate about Μ_{0}, corresponding to a new macroscopic collective angle Ø about Μ_{0. }The coupling of dM and ø leads to a new longitudinal mode, which in bulk has a frequency that is largely independent of field Η. A longitudinal mode has been observed in thin films of ferromagnets with random anisotropy, but its frequency is Ηdependent; for Η at angle θ to the film normal and fixed resonator frequency f, Η cos θ was constant to angles of 80^{°}, with Η saturating for larger angles. When the demagnetization field is included the theory yields such as Η vs θ for θ <80^{°,} thus providing evidence for the predicted angle θ. However, lower frequency resonators are needed to manifest the predicted macroscopic anisotropy energy. 

G70.00140: Spin reorientation, magnetocaloric effect and metamagnetic transitions in 50% Mn substituted RFeO_{3} (R = Eu, Ho and Er) Karthika Chandran, Santhosh P N The magnetic and magnetocaloric properties of rare earth orthoferrites are studied with 50% Mn substitution in the Fe site. Polycrystalline samples of RFe_{0.5}Mn_{0.5}O_{3}(R=Eu, Ho, Er) were synthesized and the crystal structure was resolved by Rietveld refinement of Xray diffraction patterns. All samples exhibit a PM to AFM transition near room temperature as follows:T_{N1}(EuFe_{0.5}Mn_{0.5}O_{3})~280K,T_{N1}(HoFe_{0.5}Mn_{0.5}O_{3})~290K, T_{N1}(ErFe_{0.5}Mn_{0.5}O_{3})~245K. As temperature decreases, all samples except HoFe_{0.5}Mn_{0.5}O_{3} show a sudden drop in the magnetization which is similar to the spin reorientation (SR) observed in RFeO_{3}. As temperature further reduces below SR, ErFe_{0.5}Mn_{0.5}O_{3} shows magnetization reversal for FCW curves taken in fields less than 50 Oe. Both Er and Ho based samples show high isothermal magnetic entropy change values of ΔS_{M}= 13.4 J/Kg.K (ErFe_{0.5}Mn_{0.5}O_{3}, at ~9.5 K, ΔH = 7 T) and ΔS_{M}=11.9 J/Kg.K (HoFe_{0.5}Mn_{0.5}O_{3}, at ~9.5 K, ΔH = 7 T). EuFe_{0.5}Mn_{0.5}O_{3} shows a metamagnetic transition at low temperatures. Our studies confirm that, by substituting 50% Mn in Fe site, T_{N} reduces and T_{SR} increases. High isothermal magnetic entropy change, room temperature T_{N} and T_{SR} make these interesting multifunctional materials. 

G70.00141: Phase Diagram of Magnetic System Ca_{3}Co_{2x}Mn_{x}O_{6} Benjamin White, Jani Jesenovec, Alex Mantilla The crystal structure of Ca_{3}Co_{2}O_{6 }is constructed from relatively isolated chains of Co ions oriented along the c direction. Strong intrachain magnetic exchange interactions and weak interchain coupling lead to a quasionedimensional ferromagnetic ground state. Chemical substitution studies show that Co and Mn ions alternate along the chains in the system Ca_{3}Co_{2x}Mn_{x}O_{6} and that the magnetic structure is tuned from ferromagnetic to antiferromagnetic. Symmetry breaking through exchange striction also leads to multiferroic states in the vicinity of x = 1. Such a highly complex environment is expected to produce a rich temperature vs. manganese concentration phase diagram. In this study, polycrystalline samples in the system Ca_{3}Co_{2x}Mn_{x}O_{6} were synthesized via a solid state reaction in the range 0 ≤ x ≤ 1; these samples were studied with measurements of magnetic susceptibility and heat capacity. Using these results, we constructed a temperatureMn concentration phase diagram. 

G70.00142: Roomtemperature ferromagnetism induced by boundary defects in graphene oxide nanoplatelets John Prias, Hernando Ariza, Katherine Gross, Pedro Prieto Graphene oxide nanoplatelets from bamboo pyroligneous acid (GOBPA) show roomtemperature ferromagnetism, by using the double thermal decomposition (DTD) method at different carbonization temperatures from 673 to 973 K. The GOBPA samples were characterized by using Raman, FTIR, XRD, XPS, HRTEM, IV curves, MFM and VSM techniques. Magnetic measurenets suggest that increased carbonization temperature increases graphite conversion, boundary defects, desorption of some organic compounds, phonon response and magnetization saturation, respectively. Roomtemperature ferromagnetic behavior was correlated with the variation of the boundary defect density. 

G70.00143: Many electron, spinorbit and resonant polaron effects in the THz cyclotron resonance of modulationdoped CdMnTe/CdMgTe Quantum Wells. Imtiaz Tanveer, Bruce McCombe, Adamus Zbyszek, Maciej Wiater, Grzegorz Karczewski, Tomasz Wojtowicz, Xiaoguang Wu, Francois M Peeters We present low temperature THz cyclotron resonance studies of modulationdoped CdMnTe/CdMgTe quantum wells with Mn compositions x = 13.6% in magnetic fields up to 17T. Electron densities n_{s} are (1  4) x 10^{11} cm^{2}. We focus on Bregions where the giant Zeeman splitting of Landau levels (LLs) leads to the 1↓ level crossing 0↑ at a field B_{c}. LLs are resonantly coupled and split by the spinorbit interaction, and a gap due to manyelectron exchange can also occur (Quantum Hall Ferromagnetism) when B_{c} is close to the field for fillingfactor (FF) 2 at low enough temperatures. For x=2.85% B_{c} lies at 8.65T, and CR is below our Ge:Ga detector onset. With exchange corrected LLs B_{c} should occur at ~10T, but no splitting is observed. Between 9 and 15T, FF<1.67 so only spinorbit coupling is important. Two samples do show a clear splitting of CR into two lines near 15T; strong TO phonon absorption blocks CR transmission at higher B. The origin of this splitting is not understood. For low x samples B_{c} lies between 3 and 4.5 T, depending upon temperature and spd exchange. No LL splittings are observed at 4.2 K, but at 1.5K there is a small splitting near 4.5T. A strong resonant magnetopolaron effect is also observed at high B in all samples. Effect of ee exchange will be presented. 

G70.00144: The H field dependence of magnon diffusion length basing on Boltzmann transport methods Wei Wang, Tao Liu, YuHeng Li, Jianwei Zhang The urgent demand for highcapacity and highspeed logical storage device gives rise to the further study on spin and magnon. In this abstract, we construct a new magnon Boltzmann equation from full quantum magnon Hamiltionian in magnetic insulator system, which contains the factors related to boundary injection, temperature gradient and magnetic field gradient. In our methods, we first calculate the change of magnon accumulation and magnon current with thickness of magnetic oxide film, under interaction of interface with spinmagnon, which implies that there are two parts in the process of magnon transport: magnon diffusion and magnon relaxation. Second, we calculate the change of magnon current with distance, which explains the dependence of magnon diffusion length on magnetic field theoretically. We find that the magnon diffusion length is inversely proportional to H field which was first observed by experiment [1]. Last but not least, we predict the rate of change of magnon current corresponding to the anisotropy energy change in magnetic insulator with strong anisotropic exchange energy and anisotropy energy. 

G70.00145: Interplay between oxygen vacancies, strain, and magnetism in SrMnO_{3}: a selfconsistent sitedependent DFT+U study Chiara Ricca, Iurii Timrov, Nicola Marzari, Ulrich Aschauer, Matteo Cococcioni Motivated by indications that strain and defects can stabilize a ferromagnetic ground state in normally antiferromagnetic SrMnO_{3} thin films, we use selfconsistent sitedependent (SCSD) DFT+U calculations to investigate the interplay between oxygen vacancies, strain, and magnetism in this material. 

G70.00146: Perpendicular magnetic anisotropy and spin mixing conductance in polycrystalline europium iron garnet thin films Jackson Bauer, Ethan Raphael Rosenberg, Caroline Anne Ross Rare earth iron garnets (REIG) are a diverse class of magnetic insulators in which properties such as the anisotropy and magnetostriction can be tuned by choice of rare earth ion. Garnet films with perpendicular magnetic anisotropy (PMA) are attractive for studies of spin orbit torque and chiral spin textures. PMA has been achieved in epitaxial REIG on garnet substrates due to magnetoelastic anisotropy from epitaxial lattice mismatch strain, but for making devices on nongarnet substrates, PMA without epitaxy is essential. Here we report the growth and properties of polycrystalline europium iron garnet (EuIG) with PMA. Films were grown by pulsed laser deposition followed by a rapid thermal anneal. Films on quartz (0001) substrates demonstrated PMA attributed to the inplane compressive thermal mismatch strain, whereas films on (1120) quartz, Si, and fused SiO_{2} exhibited an inplane easy axis due to tensile strain, consistent with the positive magnetostriction of EuIG. Spin transport measurements on Pt/EuIG/quartz heterostructures gave an anomalous Hall effectlike spin Hall magnetoresistance and spin mixing conductance similar to single crystal epitaxial EuIG. These results show that polycrystalline garnet can be grown with PMA, making it useful for applications in spintronics. 

G70.00147: The structural and magnetic properties of the SrTiO_{3}/SrRuO_{3}/SrTiO_{3}(100) Heterostructure Uddipta Kar, Akhilesh Singh, TsungChi Wu, Bipul Das, MingChin Chen, WeiLi Lee The itinerant ferromagnetism in the ultrathin SrRuO_{3 }films, grown by pulsed laser deposition, above a critical thickness of 34 unit cell (uc) has been reported previously by few groups[13]. On the other hand, in SrTiO_{3}/SrRuO_{3}/SrTiO_{3}(100) heterostructure and (SrRuO_{3})_{1}–(SrTiO_{3})_{5} superlattices grown by oxide molecular beam epitaxy (MBE) technique, the ferromagnetism was found to persist even with a 1uc of SrRuO_{3}[4]. It was suggested that the RuO_{6} octahedral tilting angle may be affected by the SrTiO_{3} capping layer, which in turn influences the ferromagnetism of the underlying SrRuO_{3}[4]. Detailed investigations on the SrTiO_{3 }capped and uncapped SrRuO_{3 }films are required to fully understand the intrinsic mechanism involved for the magnetic properties of ultrathin SrRuO_{3} films. In this work, Systematic studies of the structural and magnetic properties of the SrTiO_{3}(xuc)/SrRuO_{3}(yuc)/SrTiO_{3}(100) heterostructure with various thicknesses of xuc and yuc will be presented and discussed[3, 5]. 

G70.00148: Currentinduced spin polarization and anomalous Hall and Nernst effects in heterostructures with kcubed Rashba spinorbit coupling Anna Dyrdal, Anna Krzyzewska, Lukasz Karwacki, Jamal Berakdar, Jozef Barnas We will discuss our recent results on current induced nonequilibrium spin polarization and the anomalous Hall and Nernst effects within the effective models describing 2DEG in semiconductor heterostructures and perovskite oxide interfaces [L. Karwacki et al., Phys. Rev. B 97, 235302 (2018), A. Krzyzewska et al., pss RRL (2018), doi:10.1002/pssr.201800232]. We will focus on the role of kcubic Rashba spinorbit interaction which seems to play an important role in these materials. We will present the temperature dependence of the nonequilibrium spin polarization in nonmagnetic and magnetic cases, and indicate the role of the Berry phase on this effect when the system is magnetic. Moreover, we will show that there is a substantial intrinsic contribution to both anomalous Hall and Nernst effects, that are robust against impurity scattering processes. Additionally, the sign of the anomalous Nernst conductivity can be changed by tuning the temperature. This sign change appears below the critical temperature of the magnetic phase transition. 

G70.00149: Effects of second order surface anisotropy in YIG sputtered onto GGG (100) oriented substrate Roberto Rodriguez, Alexandre Oliveira, Carlos Chesman, Ricardo Borges da Costa, U. C Silva, Neymar da Costa, B.G Silva, R. L Sommer, Felipe Bohn, Marcio Correa In this work, we produced Y_{3}Fe_{5}O_{12} textured films, with thicknesses between 50 nm and 500 nm, onto (100) GdGaO by magnetron sputtering and post annealing, and investigated the first and second order surface and cubic anisotropy constants using the ferromagnetic resonance technique. The surface anisotropy constants exhibited different behaviors with film thickness, with the first order presenting the usual inverse of ferromagnetic layer thickness. Besides this inverse of thickness behavior, the second order also came up with a constant value. In the frame of spin reorientation transition phenomenon, we evaluated volume and surface contribution to the surface anisotropy. Although the second order cubic anisotropy constant is one order of magnitude stronger than the first order, they did not show any explicit thickness dependence. As an important finding of this work, in order to correctly characterize the magnetic properties of the YIG films, it is essential to measure both, the outofplane and inplane angular dependence of the FMR resonance field. 

G70.00150: Effect of electron transport on demagnetization on the shortest time scale Guoping Zhang, Yihua Bai, Tyler Jenkins, Thomas F George It is generally believed that there are at least two ways to use an ultrafast laser pulse to demagnetize a magnetic sample [1]. One is to directly photodemagnetize the system through spinorbit coupling (SOC), and 

G70.00151: The magnetic order of antiferromagnetic Mn3NiN thin films under biaxial strain David Boldrin, Freya Johnson, Andrei Mihai, Bin Zou, Jan Zemen, Will Branford, Joerg Wunderlich, Lesley Cohen We explore the magnetic phase diagram of piezomagnetic antiperovskite Mn_{3}NiN thin films grown on different substrates as a function of the induced biaxial strain using magnetotransport and neutron scattering. We find that the anomalous Hall effect is an effective probe of the outofplanemagnetisation in our films. Under compressive inplane biaxial strain, the films support a canted antiferromagnetic (AFM) state with large coercivity at low temperature that transformed at a welldefined Neel transition temperature into a soft ferrimagneticlike (FIM) state at high temperatures. In stark contrast, under tensile strain the magnetisation value decreases rapidly above the Neel transition. The resulting magnetic phase diagram shares many characteristics with that predicted for thin films of the closely related antiperovskite Mn_{3}GaN. 
(Author Not Attending)

G70.00152: Nonlocal spin transport via sustained noncollinear textures in ferromagnetic nanowires Ezio Iacocca, Thomas Silva, Mark A Hoefer Longrange, dynamic noncollinear textures [1] can be sustained in ferromagnetic nanowires by the nonlocal compensation of damping [2]. In contrast to currentdriven magnons, noncollinear textures exhibit (1) frequencies under ferromagnetic resonance that are inversely proportional to damping; (2) an excitation threshold that is proportional to the inplane anisotropy; and (3) coherence over the length of the nanowire. We analytically demonstrate that nonlinearities are fundamental to describe these characteristics. Two generic solutions when the nanowire is subject to spin injection at one edge are found, exhibiting opposite frequency tunabilities. This is in stark contrast to the linear frequency tunability predicted for spin superfluids. By micromagnetic simulations, we show that these predictions hold in the presence of inplane anisotropy and nonlocal dipole fields. 

G70.00153: Spin Hall effect in AuCu alloys Akira Musha, Kazuya Ando Spin Hall effect is a phenomenon of spin current generation from an applied charge current, arising from the two distinct regimes: intrinsic and extrinsic mechanism. The intrinsic contribution derives from the Berry curvature associated with band structure of the material while extrinsic one originates from spin dependent scattering on structural defects or impurities. In previous reports, SHE has been tuned by alloying, changing the combination of the host and impurity metals or changing the concentration of the impurities in many alloy systems. Nevertheless, the mechanism of SHE is governed by either effect, the crossover between extrinsic and intrinsic regime induced by alloying has remain elusive. 

G70.00154: Electronic vs magnonic contributions to unidirectional magnetoresistance Andrei Zholud, Ryan Freeman, Sergei Urazhdin The effect of spin current on magnetoresistance is of central importance to modern spintronics. We have investigated unidirectional magnetoresistance (UMR) in Permalloy (Py)/Pt bilayers, a magnetoelectronic effect whose origin is currently debated. Two different mechanisms are believed to contribute to UMR. The first mechanism is due to magnon generation/suppression in Py by pure spin current produced by the spin Hall effect in Pt. The second one is due to spin dependent electronic scattering near the Py/Pt interface, where spin accumulation is modulated due to the spin current generated in Pt. By engineering the geometric and material properties of our samples, we enhanced magnon relaxation, thus suppressing the spin currentinduced changes of magnon population. We observed a significantly reduced UMR, suggesting that this effect in the studied structures is dominated by the magnon contribution. We also discuss how the dependence of UMR on field temperature provides information about the spectral characteristics of the generated magnons, and their generation mechanisms. Our results suggest the UMR can be utilized as an efficient technique for the characterization of spin currentdriven dynamical magnetization states. 

G70.00155: Observation of the evolution of magnetic domain structures related to magnetic polaron cluster formation in a single crystal of EuB_{6} Dibya Sivananda, Ankit Kumar, Arif Ali, pintu das, Jens Muller, Satyajit Banerjee EuB_{6} is a ferromagnetic semimetal which shows colossal magnetoresistance at a temperature of T_{c1}~15.5K and also exhibits nanoscale phase separation between conducting ferromagnetic and insulating paramagnetic domains. Here, we have performed high sensitivity magnetooptical imaging of EuB_{6} which images the local magnetic field distribution on the surface of a sample. From our measurements, we identify three characteristic boundaries, T^{*}(H), T^{*}_{c1}(H) and T_{c2}(H), in a field  temperature magnetic phase diagram and identify their behavior with field. Using scaling and modified Arrott’s plot analysis of isothermal bulk magnetization data, we identify critical transition into a ferromagnetic state below T_{c2} = 12 ± 0.2 K. Highresolution imaging of magnetic domains reveals large magnetized domains below T_{c2}. With increasing T (> T_{c2}) the magnetic domains disintegrate into fingerlike patterns before fragmenting into disjoint magnetized puddles at T^{*}_{c1} and ultimately disappearing at T*. At T^{*}_{c1} we observe a significant increase in the spatial inhomogeneity of the local magnetic field distribution associated with the magnetic domains disintegrating into smaller magnetized structures. We explain our results via the formation and the subsequent coalescing of magnetic polaronic clusters. 

G70.00156: Towards subwavelength spin and charge control of nitrogen vacancy centers using superresolution microscopy Harishankar Jayakumar, Siddharth Dhomkar, Jacob Henshaw, Carlos Meriles Super resolution microscopy has enabled addressing single nitrogen vacancy centers with a spatial resolution that is an order of magnitude higher than the diffraction limit. Here, we present the latest experimental results towards the utilization of stimulated emission depletion based super resolution techniques to manipulate the charge and spin degrees of freedom of a diamond nitrogen vacancy (NV) center. This technique is applicable to various NV center sensing modalities and data storage applications that demand high spatial resolution with minimal perturbation of the NV environment. 

G70.00157: Thermally induced spin polarization in 2D systems with Rashba spinorbit interaction Anna Dyrdal, Jozef Barnas, Vitalii Dugaev, Jamal Berakdar We present the theory of spin polarization induced by a temperature gradient (heat current) in a magnetized twodimensional electron gas (2DEG) with a Rashba spinorbit interaction. Within the Matsubara Green’s function formalism, we calculated the temperature dependence of the spin polarization not only in nonmagnetic case but also in the presence of a nonzero exchange field oriented arbitrarily in the space. For the magnetic system, among others, we identified a term in the spin polarization that stems from the Berry curvature of the corresponding electronic bands. 

G70.00158: Frustrated bilayer spin one XY model on the honeycomb lattice Antonio Pires The study of quantum magnetism on geometrically frustrated lattices has been an active field of interest due to the possibility of finding new states of matter such as spin liquids and nematic phases.In this context, honeycomb lattices have attracted a lot of attention due to their interesting and poorly understood magnetic properties.The honeycomb lattice has the lowest value z =3 of the coordination number, leading to a strong effect of quantum fluctuations. In contrat to the spin 1/2 model, not so much theoretical attention has been dedicated to the S = 1 model in spite of its relevance to several materials with spin one. Here I study the spin one bilayer XY antiferromagnet on the honeycomb lattice at zero temperature, with nearestneighbor J_{1} and nextnearest neighbor J_{2} exchange interactions and singleion easy plane anisotropy, using the SU(3) Schwinger boson formalism. The ratio between the interlayer to the intralayer near neighbor exchange interactions exhibits a quantum phase transition at a critical ratio 13.8 that separates the Neel phase from a quantum disordered paramagnetic phase. The effect of next near neighbor interactions is discussed and the phase diagram is presented. 

G70.00159: Cooperative TwoSublattice Model for Frustrated Pyrochlore Gd_{2}FeSbO_{7} Saikat Nandi DC and AC magnetization and heat capacity data of frustrated pyrochlore Gd_{2}FeSbO_{7} are studied within the framework of cooperative twosublattice model [1] in presence of easyplane singleion anisotropy at Gdsite. There are three types of interactions: intrasublattice GdGd antiferromagnetic interaction, intrasublattice FeFe ferromagnetic interaction, and intersublattice GdFe antiferromagnetic interaction. The interaction between Fe^{3+} 3d moments, which is stronger than 4f^{7} interaction, generates a molecular field at Gdsite through a weaker cooperative GdFe ramification. Fe^{3+} sublattice orders at T_{C} ~ 5 K possibly in ‘twoin, twoout’ spinconfiguration due to FM exchange interaction. Gd moments are fixed perpendicular to local <111> axes of tetrahedron due to crystalfield anisotropy and antiferromagnetic GdGd exchange interactions. Such magnetic structure for Gd tetrahedra may resemble the PalmerChalker ground state, which is subdued due to stronger Bsite FeFe interactions. Saturation magnetization of 13.04μ_{B} is expressed as the vector coupling of directional magnetic moments of Gd and Fe. Finally magnetocaloric properties of Gd_{2}FeSbO_{7} are estimated from magnetization and heat capacity results. 

G70.00160: Density functional study of the electronic structure of the noncollinear helical magnet Ba_{3}NbFe_{3}Si_{2}O_{14 }(Langasite): Magnetic exchange and DzyaloshinskiiMoriya interactions Churna Bhandari, Sashi Sekhar Satpathy Ba_{3}NbFe_{3}Si_{2}O_{14 }is an iron based compound, which consists of a Fe trimer in the abplane with a large spin moment ≈_{ }5 μ_{B }/Fe. The spins of Fe trimer form a 120^{0 }noncollinear antiferromagnetic structure in the abplane followed by a helical structure with a propagation vector q = (0,0,1/7). We study the electronic band structure using density functional theory (DFT), which shows an insulating gap due to the exchange splitting of the 3d bands. The features of the computed optical spectra are discussed in terms of the band structure. In addition, we study the magnetic exchange parameters by mapping the density functional total energy to exchange models. The absence of inversion symmetry in conjunction with the spinorbit interaction leads to the DzyaloshinskiiMoriya interaction (DMI) of the type D.S_{1} x S_{2}, which is necessary to explain the observed spinwave energies. We study the DMI from a model extracted from the DFT in order to gain insight into the magnetic interactions in the system. 

G70.00161: ‘LocalIsing’ type magnetism and metamagnetism in the rareearth pyrogermanates Keith Taddei, liurukara Sanjeewa, Joseph Kolis, Athena S. Sefat, Clarina Dela Cruz, Daniel Pajerowski The rareearth pyrochlores have long been the system of choice for the study of frustrated magnetism due to the inherent geometric frustration of the rareearth sublattice which can beget ‘localIsing’ behavior. The combination of a large localanisotropy and geometric frustration lead to the famous ‘spinice’ rules and consequently to exotic physics such as magnetic monopoles. The rareearth pyrogermanate family of materials has seen significantly less study yet has similar potential due to a spiraling triangular rareearth sublattice. We report the results of neutron scattering experiments on rareearth pyrogermanate Er_{2}Ge_{2}O_{7} which reveal a 3D spiral magnetic structure below 1.2 K. Under applied field we find a metamagnetic transition of spinflip type indicating a large local anisotropy of the rareearth site. This transition selectively inverts magnetic moments antiparallel to the applied field yet leaves to moments along their locally determined easyaxis. This describes a localIsing type behavior as seen in the spinice pyrochlores and encourages further study of these materials. 

G70.00162: Observation of magnetoelastic effects in a quasionedimensional spiral magnet Chong Wang, Daiwei Yu, Xiaoqiang Liu, Rongyan Chen, Xinyu Du, Biaoyan Hu, Lichen Wang, Kazuki Iida, Kazuya Kamazawa, Shuichi Wakimoto, Ji Feng, Nan Lin Wang, Yuan Li We present a systematic study of spin and lattice dynamics in the quasionedimensional spiral magnet CuBr_{2}, using Raman scattering in conjunction with infrared and neutron spectroscopy. Along with the development of spin correlations upon cooling, we observe a rich set of broad Raman bands at energies that correspond to phonondispersion energies near the onedimensional magnetic wave vector. The lowenergy bands further exhibit a distinct intensity maximum at the spiral magnetic ordering temperature. We attribute these unusual observations to two possible underlying mechanisms: (1) formation of hybrid spinlattice excitations and/or (2) “quadrumerization” of the lattice caused by spinsinglet entanglement in competition with the spiral magnetism. 

G70.00163: Effects of boundary on a kagome Ising model with magneticcharge interaction Tomonari Mizoguchi, Yasuhiro Hatsugai In frustrated Ising models on kagome and pyrochlore lattices, the system is described by conserved charge degrees of freedom [1]. Conserved charges serve as a "fractionalized" elementary excitation, which characterizes the topological nature of spin liquid state. The conserved charge description is useful to seek novel states induced by perturbations against the conventional nearestneighbor model. For instance, it has been found that fatherneighbor exchange interactions induce an interaction between the charges, which becomes a source of novel spin liquid state [2]. 

G70.00164: Spinflip and magnetoelectric coupling in acentric and nonpolar Pb_{2}MnO_{4} HungDuen Yang, D Chandrasekhar Kakarla, HungCheng Wu, DongJie Hsieh, PoJung Sun, JiunnYuan Lin, JimLong Her, Yasuhiro H. Matsuda, Liangzi Deng, Gooch Melissa, Paul C. W. Chu Acentric and nonpolar Pb_{2}MnO_{4} was predicted to exhibit unique multipiezo induced magnetoelectric (ME) phenomena [1]. Here, we present the results of measurements from magnetization as well as the dielectric, as a function of temperature (T), magnetic field (H), pressure (P), and electric field (E) primarily to address the ME coupling and identify the underlying mechanism behind this phenomenon. Magnetization measurements reveal the antiferromagnetic (AFM) ordering of Mn^{4+} spins at T_{N }= 17 K. For T_{N} 17 K, a robustly multiple partial spinflip transitions were also observed. The existence of ME coupling is supported by the observed dielectric anomaly near T_{N}. The lattice dielectric response is strongly influenced by spinflip transitions that trigger the pronounced ME coupling below the T_{N}. The magneticfieldinduced ME phenomenon in Pb_{2}MnO_{4} has been ascribed to the strong coupling of lattice polarization with the magnetic interactions and thereby offers a route to attain novel ME materials. 

G70.00165: Probing variable range hopping lengths by magneto conductance in carbonized polymer nanofibers Yung Park, Kyung Ho Kim, Samuel LaraAvila, Hans He, Hojin Kang, Sergey Kubatkin Using magneto transport, we report hopping length scales in the variable range hopping conduction of carbonized polyacetylene and polyaniline nanoribers. In contrast to pristine polyacetylene nanofibers that show zero magneto conductance at large electric fields (it clarifies the charge and spin states of 1D topological insulator, namely the solitons in polyacetylene nanofibers.), carbonized polymer nanofibers display a negative magneto conductance that decreases in magnitude but remains finite with respet to the electric field. We show that this behavior of magneto conductance is an indicator of the electric field and temperature dependence of hopping length in the gradual transition from the thermally activated to the activationless electric field driven variable range hopping transport. This reveals magneto transport as a useful tool to probe hopping lengths in the nonlinear hopping regime. 

G70.00166: Single Crystal Synthesis of Frustrated Magnet Y_{0.5}Ca_{0.5}BaCo_{4}O_{7} Yuki Tatsumi, Linda Ye, Takehito Suzuki, Joseph Checkelsky Neutron scattering experiments on Y_{0.5}Ca_{0.5}BaCo_{4}O_{7} powders have reported suppression of magnetic order and flat magnonic bands down to low temperatures [1]. In order to study the physical properties of these materials in greater detail, we have synthesized bulk single crystals of this compound by the optical floating zone method. We present the details of the material preparation and characterization, including the dependence of magnetic properties on the growth conditions as well as plans for probing the unique magnetic dispersion of this system. 

G70.00167: Role of antisite disordering in magnetic properties of Sm2NiMnO6 double perovskite Supriyo Majumder, Malvika Tripathi, R.J. CHOUDHARY, D. M. Phase We have investigated the structural, magnetic and electronic properties of Bsite disordered Sm_{2}NiMnO_{6} DP oxide. XPS measurements indicate mixed valency of both Ni^{2+}/^{3+} and Mn^{4+}/^{3+} species. RE_{2}NiMnO_{6} ordered DP is commonly believed to show two magnetic phase transitions viz, PMFM transition at T_{C} due to Ni^{2+/3+}OMn^{4+/3+} super exchange interaction and at T_{f} due to coupling of RE spins with NiMn network [1, 2]. In our present study, we have observe that the presence of intrinsic Bsite disorder results in an additional AFM coupling [3], mediated by Ni^{2+/3+}ONi^{2+/3+} and Mn^{4+/3+}OMn^{4+/3+} pairs. In M(T) measurements we have observed an inverted cusp like trend and thermal irreversibility in FCC and FCW cycles in T_{f}<T<T_{C} both of which vanishes on application of higher magnetic fields. The observed thermal hysteresis indicates towards the possibility of either coexisting FMAFM phases or magnetic frustration originating from different exchange interaction paths between mixed valence ions. MH isotherms in T_{f }<T<T_{C} exhibit two step reversibility loop behavior, which further confirms the presence of competing FMAFM phases. 

G70.00168: Specific heat measurements of Ce_{2}Zr_{2}O_{7} in magnetic field Roman Movshovich, Andrea Bianchi, Jérémie Dudemain, Michael Nicklas, Evan Smith, Bruce Gaulin, Jonathan Gaudet We measured specific heat of the pyrochlore Ce_{2}Zr_{2}O_{7 }in magnetic field up to 14 T and temperatures down to 60 mK. In zero field we observe a monotonic rise of the specific heat, with the values of C/T reaching 30 J/molK at 100 mK, and without saturation, at least in some compounds. The field was applied in either [100] or [110] directions. Even small magnetic field on the order of a kilogauss pushes the entropy up in temperature, developing a broad maximum in C(T), which moves up in temperature with increasing magnetic field. The calculated entropy is consistent with a doublet ground state. Extreme sensitivity to small magnetic field is consistent with a disordered zerofield ground state, with entropy piling up towards T=0, indicating a possible spinliquid. 

G70.00169: Monte Carlo Simulations of Classical Spin Liquids Hannah Price, Xiaojian Bai, Martin Mourigal Using Monte Carlo, we simulate the ground state spin configurations of spin liquids at low temperatures. The program requires only basic unit cell and coupling energy information to be run. Thus, most materials can be easily simulated. We have modeled the frustrated diamond lattice for a range of J2/J1 energies. As well as the frustrated pyrochlore lattice. In particular, we compare the modeled critical temperature and structure factor, with that from previous models and experiments. 

G70.00170: Impact of interlayer coupling on magnetic skyrmion size Caner Deger, Ilhan Yavuz, Fikret Yildiz We study the magnetic skyrmion formation in thinfilm stacks, consist of two magnetic layers separated by a nonmagnetic spacer. The LandauLifshitzGilbert equation, comprising the spin precession term and the damping term with all relevant contributions, is numerically solved within the micromagnetic framework. Through extensive systematic calculations, we find that skyrmion size can be controlled by the interlayer exchange coupling, as well as the external magnetic field. zcomponent of the magnetization of the layers, which can be tailored by the coupling, strongly affects the skyrmion diameter. The skyrmion phase coexists with the helical phase for both types of coupling, being antiferromagnetic or ferromagnetic, in the absence of the magnetic field. The size of the skyrmions at zero field can also be controlled by the interaction. We anticipate that our predictions not only expand our fundamental understanding of the physical mechanisms responsible for skyrmion formation but also provide rational basis for the nextgeneration logic/memory device applications. 

G70.00171: Currentdriven coherent magnetic skyrmion generation Caner Deger, Ilhan Yavuz, Fikret Yildiz The nextgeneration logic and memory devices which use magnetic skyrmions as the information carrier are frequently studied due to its remarkable magnetic stability, extremely compact size and verylowcost driving force within the nanostructure. To realize skyrmionbased spintronic devices, it is essential to understand the dynamics of skyrmion generation. In this study, we have carried out a systematic theoretical study on coherent magnetic skyrmion generation by an antinotch in a channel of finite width. We found that, the coherent skyrmion generation is crucially effected by both damping (α) and nonadiabaticity (β) parameters, as well as the geometry of the antinotch. The periodicity of the generation is also investigated for certain current densities and α/β ratios. We anticipate that our predictions provide rational basis for skyrmionbased devices in which skyrmions are used as information carriers. 

G70.00172: Topological Hall effect in diffusive ferromagnetic thin films with spinflip scattering Shulei Zhang, Olle Heinonen So far, most electrical measurements of magnetic skyrmions have been based on the interpretation that the topological Hall (TH) resistivity is proportional to the number of skyrmions multiplied by the magnetic flux quantum, which only applies to bulk systems in the strong exchangecoupling and nondiffusive regimes. In this work, we theoretically studied the TH effect in diffusive ferromagnetic metal thin films by solving a Boltzmann transport equation in the presence of spinflip scattering. We found that, even in the strong exchange limit, the TH effect itself is not topologically protected in the presence of spin diffusion, owing to the spin accumulation built up in the vicinity of the skyrmions. A more general formula for the TH resistivity was derived, which establishes the relation between the TH resistivity and the ratio of the spin diffusion length to the skyrmion radius and would be increasingly important for extracting information about skyrmion density from experimental data when the size of room temperature skyrmions is further reduced to tens of nanometers, close to the spin diffusion lengths of most transition metal ferromagnetic thin films. 

G70.00173: Robust Hund rule without Coulomb repulsion and exclusion principle in quantum antiferromagnetic chains of composite half spins Solomon Duki, Yikuo Yu Quantum spin chains with composite spins have been used to approximate conventional chains with higher spins. For instance, a spin 1 (or 3/2) chain was sometimes approximated by a chain with two (or three) spin 1/2’s per site. However, little examination has been given as to whether this approximation, effectively assuming the first Hund rule per site, is valid and why. In this work, the validity of this approximation is investigated numerically. We diagonalize the Hamiltonians of spin chains with a spin 1 and 3/2 per site and with two and three spin 1/2’s per site. The low energy excitation spectrum for the composite chain is found to coincide with that of the conventional chain. We find that as the system size increases, an increasingly larger block of consecutive lowest energy states with maximal spin per site is observed, robustly supporting the first Hund rule even though the exclusion principle does not apply and the Coulomb repulsion is absent. We show that this effective Hund rule emerges as a plausible consequence of the Lieb–Mattis theorem, which is originally for the ground state of ferrimagnetic and antiferromagnetic spin systems. 

G70.00174: Quantum phase interference in nanomagnetic particles coupled to the Josephson φ_{0} junction GwangHee Kim, HanYong Choi We study suppression of magnetization tunneling in nanomagnetic systems coupled to the Josephson φ_{0} junction. Employing spin coherent state path integral method, we find that the tunnel splitting is topologically quenched by the bias current applied to the junction as well as an external magnetic field along the hard axis. Considering tunnel splitting as a function of the current, we show that the quenching period is controlled by the external magnetic field and the number of frozen points decreases with increasing the magnetic field. The condition for switching from oscillations to the monotonic growth of the tunnel splitting is presented. 

G70.00175: Giant superconducting proximity effect on spintronic anisotropy Krzysztof Wojcik, Maciej Misiorny, Ireneusz Weymann We investigate theoretically the interplay of proximity effects due to the presence of a superconductor and normal ferromagnetic leads on the formation of the spintronic quadrupolar exchange field in a largespin magnetic molecule. We show that the spintronic anisotropy can be enhanced by a few orders of magnitude, and tuned by changing the strength of coupling to the superconductor. Especially large anisotropy is generated in the vicinity of the charge parity changing transition of the molecule. We also provide predictions of measurable spectral properties being the hallmarks of these phenomena. The calculations are performed with the aid of the numerical renormalization group method. 

G70.00176: Phase transitions in the onedimensional transverse Ising model in a longitudinal magnetic field Osiel Bonfim, B. Boechar, J. Florencio The phase transitions in the onedimensional transverse Ising model in the presence of a longitudinal magnetic field were studied by the quantum fidelity method. We used exact diagonalization to obtain the groundstate energies and corresponding eigenvectors for lattice sizes up to 24 spins.The maximum of the fidelity susceptibility is used to locate the various phase boundaries present in the system. The type of dominant spin ordering for each phase was identified by examining the corresponding groundstate eigenvector. For a given antiferromagnetic nearestneighbor interaction ($J_2$), we calculated the fidelity susceptibility as a function of the transverse field ($B_x$) and the strength of the longitudinal field ($B_z$). The phase diagram in the ($B_x,B_z$)plane shows three phases. These findings are in contrast with the published literature that claims that the system has only two phases. For $B_x < 1$, we observed an antiferromagnetic phase for small values of $B_z $ and a paramagnetic phase for large values of $B_z$. For $B_x > 1$ and low $B_z$, we found a disordered phase that undergoes a phase transition to a paramagnetic phase for large values of $B_z$. 

G70.00177: Spin wave excitation and propagation in ultrathin nmthick yttrium iron garnet films Hanchen Wang, Tao Liu, Chuanpu Liu, Jilei Chen, Youguang Zhang, Weisheng Zhao, Mingzhong Wu, Haiming Yu Magnonics has received increasing attention over the past decades, and it is widely considered to open up new opportunities to transport information by using spin waves (SWs) without charge currents. In our paper, we investigate experimentally the excitation and propagation of SW in 7nm thick yttrium iron garnet (YIG) thin films with an ultralow damping constant. On the top of YIG, conventional coplanar waveguides are integrated to excite a large series of shortwavelength spin waves (SWs). The scattering parameters are measured by using a vector network analyzer, which give access to observe the transmission of SW in the films. Consequently, by utilizing the experimental results, we calculate and extract the group velocity as well as the dispersion relation of SWs. Our work may be useful for providing the basis for SW logic devices at GHz rates with low power consumption. 

G70.00178: Local shortscale correlations and the origin of negative magnetization Malvika Tripathi, T. Chatterji, S. Majumder, R. M. Choudhary, D. M. Phase Negative Magnetization (NM) defined as the opposite alignment of net magnetization with respect to applied magnetic field in magnetically ordered systems has been associated with a number of unsettled debates regarding the origin and reliability of this phenomena. The presence of two highly neutron absorbing isotopes of natural Gd has prevented to understand the microscopic magnetic structure and consequently the microscopic outlook of NM in GdCrO_{3, }so far. We have utilized λ = 0.4994Å hot neutrons, a value much higher than the resonance energy, to record the thermal evolution of neutron diffraction patterns. Using magnetic pair distribution function analysis, significant local short range Gd^{3+} correlations in disordered state are observed ranging upto ~9 Å. Calculations suggest the frustated S= 3 ground state of locally ordered Gd ions with competing FM AFM exchange interactions and states corresponding to NM are comparitively more stablized. The extermely small excitation gap between energy levels is argued to be resonsible for the different spin state populations characterized by distinct kinetic rates corresponding to cooling and warming cycles, which explains the observed path dependency of NM in GCO. 

G70.00179: Anomalous Nernst effect in a microfabricated Weyl magnet Mn_{3}Sn Hideki Narita, Tomoya Higo, Ikhlas Muhammad, Satoru Nakatsuji, Yoshichika Otani Weyl magnets have attracted much attention in condensed matter physics due to both the fundamental interest and the potential application of a new thermoelectric power generation and heat current sensor. An anomalous Nernst effect is a thermoelectric phenomenon typically observed in ferromagnets under the application of a temperature gradient. The anomalous Nernst effect provides a simple and powerful tool to track the position and motion of a domain wall propagating. Recent theoretical and experimental studies have shown that magnetic domains exist in noncollinear antiferromagnetic Weyl magnets. 

G70.00180: Domain wall motion influenced by a standing spin wave in antiferromagnetic systems Inhyeok Choi, hyoseok Kim, Jongseok Lee In antiferromagnetic systems, spin dynamics are described by coupled LandauLifshitzGilbert equation for two order parameters of staggered and magnetic moments. It is also known that the timevarying magnetic field drives a collective motion of domain wall (DW). By using a micromagnetic simulation, we investigate a coupling effect between the spin wave and the DW motion which can be simultaneously driven by the oscillating magnetic field. In an antiferromagnetic nanorod, a standing spin wave can be formed when its length is multiples of the wavelength of the excited spin wave. Depending on a phase relationship between the DW position oscillation and the standing spin wave, we find that the DW position oscillation is significantly influenced; its oscillation amplitude becomes negligible in the outofphase condition, and is enhanced by about twice in the inphase condition. 

G70.00181: Structure and Magnetic Properties of Gd_{2x}Sr_{x}NiO_{4}, a RuddlesdenPopper type solid solution Renata Miranda, Raul Zúñiga Medina, Pablo De la Mora, Jorge Barreto, Gustavo Tavizón Gd_{2x}Sr_{x}NiO_{4} complex oxide of the RuddlesdenPopper series, was first prepared by James, M. et al.[1] Several compositions of the Gd_{2x}Sr_{x}NiO_{4 }system were prepared by the complex polymeric route (Pechini). In this work we report the Sr composition stability range for this solid solution. Crystal structure of samples in the 0.75≤x≤1.25 range, were studied by Rietveld structure refinements. Magnetic measurements of samples (2300 K) show a CurieWeiss paramagnetic behavior for all x compositions, with a weak antiferromagnetic coupling. Electrical properties were measured in the 20300 K range and we found that this system displays a metalinsulator transition for x≥1.0. Spectroscopic data (UVVisNIR) at room temperature and magnetic moment measurements of this system reveal the nature of Ni oxidation states of this system. 

G70.00182: Structure, Electrical and Magnetic properties of Sm_{1x}Ca_{x}CrO_{3}, orthochromites Alejandro Duran Hernandez, Jorge Barreto, Jesús Ángel Arenas, Pablo De la Mora, Gustavo Tavizón


G70.00183: A possible Hund’s metal and unusual secondorder metal insulator transition in perovskite La_{1x}Pr_{x}RuO_{3} Zongyao Li, José Antonio Alonso, Jianshi Zhou 4d perovskite LaRuO_{3} is a paramagnetic metal whereas PrRuO_{3} is a paramagnetic insulator. Although Ru^{4+} ruthenates have shown very rich physics due to the subtle interplay of Coulomb repulsive potential U, Hund’s rule coupling J, the crystalfield splitting Δ, and the spinorbit coupling (SOC), limited information of Ru^{3+} perovskite RRuO_{3} (R=rare earth metals) family has been obtained since these perovskites have to be synthesized under high pressure. We report a successful synthesis of perovskite La_{1x}Pr_{x}RuO_{3} compounds by spark plasma sintering. A thorough characterization on La_{1x}Pr_{x}RuO_{3 }system has been made by measurements of magnetic and transport properties and specific heat. The samples La_{1x}Pr_{x}RuO_{3} (0.2 < x < 0.8) exhibit a secondorder metalinsulator transition as temperature decreases without any sign of magnetic order in the insulator phase. Due to the reduction of RuORu bond angle, substituting La^{3+} ions with smaller Pr^{3+} ions reduces the bandwidth so as to lead to an insulator phase at low temperatures. The strong SOC and Hund’s coupling on low spin 4d^{5 }Ru^{3+} are responsible for the anomalous metallic phase found in LaRuO_{3} and the absence of magnetic ordering in the insulator phase in La_{1x}Pr_{x}RuO_{3.} 

G70.00184: Evidence of Martensitic Phase Transitions in Boron Substituted NiMnIn Thin Films Sudip Pandey, Alpha N'Diaye, Igor Dubenko, Anil Aryal, Dipanjan Mazumdar, Sujoy Roy, Shane Stadler, NAUSHAD ALI NiMnInB thin films were synthesized on Si substrates using ultrahigh vacuum magnetron sputtering. Metamagnetic transitions with thermal hysteresis have been observed on 30 nm thin films using the magnetization measurements. The temperature dependences of the magnetization curves were found to be similar to those of the bulk counterpart. Electronic and magnetic properties of NiMnInB thin films were studied using Xray absorption spectroscopy (XAS) and Xray magnetic circular dichroism (XMCD). From the XAS and XMCD spectra, we have observed that Ni plays a dominant role in the overall magnetism. Elementspecific XMCD hysteresis loops of Ni in the NiMnInB films were measured as a function of temperature and observed minimum magnetic hysteresis at martensitic transformation. Possible mechanisms responsible for the changes in electronic and magnetic properties of thin films through the effect of redistribution of d electrons are discussed. 

G70.00185: Beyond spin wave theory on a 5d transtionmetal oxide Jinkwang Kim, Jungho Kim, Bumjoon Kim 5d transition metal oxides (TMOs) offer a new playground for quantum magnetism with some unique features. For instance, a Heisenberg antiferromagnet in square lattice iridate Sr2IrO4 reveals similar lowenergy effective physics with highTc superconductor parent antiferromagnet, La2CuO4, with its spinorbit coupling driven isospins. However, there are some different features in detailed physics between them, one of which is small deviation of lowenergy magnetic dispersion from what spin wave theory gives. In this regard, we used resonant inelastic xray scattering to show that the spin wave theory cannot perfectly explain the lowenergy magnetic behavior of a 5d transitionmetal oxide, Sr2IrO4. The high momentumresolution lowenergy dispersion and its temperature dependent behaviors cannot be fully understood only by spin wave theory, but higherorder exchange order terms should be included to describe these behaviors. 

G70.00186: Fluxdriven and geometrycontrolled spin filtering for arbitrary spins in aperiodic quantum networks Amrita Mukherjee, Arunava Chakrabarti, Rudolf Roemer We demonstrate that an aperiodic array of certain quantum networks comprising magnetic and nonmagnetic atoms can act as perfect spin filters for particles with arbitrary spin state.This can be achieved by introducing minimal quasione dimensionality in the basic structural units building up the array, along with an appropriate tuning of the potential of the nonmagnetic atoms,the tunnel hopping integral between the nonmagnetic atoms and the backbone, and, in some cases,by tuning an external magnetic field.The proposed networks have close resemblance with a family of recently developed photonic lattices,and the scheme for spin filtering can thus be linked, in principle,to a possibility of suppressing any one of the two states of polarization of a single photon, almost at will.We use transfer matrices and a real space renormalization group scheme to unravel the conditions under which any aperiodic arrangement of such topologically different structures will filter out any given spin projection following an energyindependent commutation of the transfer matrices.Our results are analytically exact,and corroborated by extensive numerical calculations of the spin polarized transmission and the density of states of such systems. 

G70.00187: Spin Hall Torque Mediated by Metallic Antiferromagnet Yan Wen, Fengjun Zhuo, Aurelien Manchon, Xixiang Zhang We report an enhancement of spin current in //Ta/IrMn/Cu/NiFe multilayer heterostructure. A thin metallic IrMn can enhance the spin current from Ta to NiFe. The spin current enhancement with a pronounced maximum value around the Neel temperature of the thin antiferromagnetic (AFM) layer was found. Through varying the measurement temperature and the thickness of the AFM layer, both electronic and magnonic spin current was observed. At low temperatures, where the convertance is weak, a comparable small spin conductivity is observed. The spin conductivity increases when the temperature rises until Neel temperature due to a more convertance process from electronic spin current to magnonic spin current. The spin conductivity decreases when further rising temperature, in which the AFM order is wellestablished and magnonic spin current starts to vanish. 

G70.00188: Spinorbit torque generated by Pd oxides Satoshi Haku, Hongyu An, Akira Musha, Kazuya Ando Currentinduced spinorbit torques enable the manipulation of magnetization in ultrathin ferromagnetic metals. Recent studies have revealed that the spinorbit torques can be generated by spinorbit coupling at ferromagneticmetal/heavymetaloxide interfaces. Here, we report the generation of spinorbit torques using Pd oxides, PdOx. Pd is known as a heavy metal with high conversion efficiency between charge and spin currents because fo the strong spinorbit coupling. In this work, we quantified the spinorbit torques generated by PdOx using spintorque ferromagnetic resonance for NiFe/PdOx bilayers with various oxidation levels. The oxidation level of the PdOx layer was manipulated by varying the oxygen gas flow during the reactive sputtering. By increasing the oxidation level of the PdOx layer, we found that the dampinglike torque efficiency is significantly suppressed, showing vanishingly small interface spinorbit torques in the NiFe/PdOx bilayers. This is in stark contrast to the spintorque generation in NiFe/PtOx bilayers, where the dampinglike torque efficiency is not sensitive to the oxidation level of PtOx. Our results therefore will be essential for fundamental understanding of the spinorbit torques generated by metal oxides. 

G70.00189: Firstprinciples study of the carrier doping effect on allHeusler GMR junctions Fumiaki Kuroda, Tetsuya Fukushima, Tamio Oguchi In this work, we investigate interfacial magnetic couplings and spindependent transport property in allHeusler based CPPGMR junctions with a semimetallic Fe_{2}VAl spacer on the basis of firstprinciples calculations. A halfmetallic ferrimagnet Mn_{2}VAl is used for a spin injector and is thought to be highly promising for spintronics devices at room temperature because the expected current to flip the spin would be rather low. It is found from our calculations that, in MnMnVAl termination, the interfacial Mn atoms are antiferromagnetically coupled with V atoms of Fe_{2}VAl. In addition, halfmetallic states are also preserved in the interfacial reigion. The transport property is governed by an electron pocket in the band structure, originating from the V d states. The carrier doping effect from band matching leads to a new function in CPPGMR junctions. When carriers are introduced in the spacer by a gate voltage, magnetoresistance might be changed significantly. Moreover, from comparison with a spin injector with another halfmetallic Heusler alloy Co_{2}MnSi, the chemical trend in this type of CPPGMR junctions is discussed. 

G70.00190: Investigation of hBN/Graphene Spin Valve Tingyu Qu, Junye Huang, Deyi Fu, Jiawei Liu, Barbaros Ozyilmaz Spintronics via twodimensional materials offer promising applications in spin communications. Due to the extraordinary mobility and long diffusion length, graphene is still the subject of intense interest in spin transport. This study focuses on the investigation of the spin lifetime and diffusion length in graphene spin valve, including the extrapolation of the exponential decay of the spin signal with channel length and Hanle precession model. The graphene spin valve exhibits large nonlocal spin signal up to 40 Ω, with small switching field less than 200 Gauss. The extracted spin lifetime was between 100 and 200 ps, and the diffusion length was more than 4 μm. The spininjection efficiency in graphene spin valve is further improved by controlling direct current as an injection source and using hBN as a tunneling barrier. 

G70.00191: Spin transport properties in ultrathin black phosphorus Jiawei Liu, Deyi Fu, Barbaros Oezyilmaz The discovery of graphene and twodimensional materials provided new platforms to study electronic spin transport and to be used for novel spintronics applications. Graphene has been shown to exhibit desirable spin transport properties such as long spin life time^{[1]}, long spin relaxation length^{[2]} and up to 100% spin injection efficiency^{[3]} , even at room temperature. Beyond graphene, in our previous work, we demonstrated all electric spin injection, transport and detection in ultrathin black phosphorus. In the nonlocal spin valve geometry, the measured spin relaxation time is as high as 4ns with spin relaxation lengths exceeding 6 μm^{[4]}. In this work, we measured the spin signal and lifetime at different doping level in the black phosphorus. We also studied the relation between the spin and momentum relaxation time as a function of temperature. 

G70.00192: The role of the spinorbit coupling in the Transition metal dichalcogenides vertical spin valves Xinhe Wang, Xiaoyang Lin, yuan cao, Weisheng Zhao As a family of twodimensional (2D) layered materials, Transition metal dichalcogenides (TMDCs) MX2 (M=Mo,W; X=S,Se) have been demonstrated to have potential for applications in the field of spintronics because of their strong spinorbit coupling, spinsplitting with broken inversion symmetry and spinvalley degrees of freedom. In our work, the 2D MX_{2} were grown using chemical vapor deposition, and vertical spin valves with crossstrip geometry were constructed. the spin valve effects are measured, with layer and stacking variations. Which show the signature of the spinvalley coupling and spinorbit torques. they pave the way for magnetic and electric control of spin and valleypolarized transport in magnetic tunneling junctions. Then, metallic behavior of the junction barrier is discussed; the temperature (50K300K) dependence of the magnetoresistance ratio is reported; the role of the anisotropic magnetoresistance in the typical crossstrip geometry and the annealing effect on the device is discussed. Finally, the feature of the vertical spin valves based on the different TMDCs are listed and compared. 

G70.00193: Edge magnetic properties and transport of spin current in an SU(2)symmetric Kitaev spin liquid Vanuildo De Carvalho, Hermann Freire, Eduardo Miranda, Rodrigo G Pereira We investigate the edge magnetism and the spin transport properties of an SU(2)symmetric Kitaev spin liquid (KSL) model put forward by Yao and Lee [Phys. Rev. Lett. 107, 087205 (2011)] on the honeycomb lattice. In this model, the spin degrees of freedom fractionalize into a Z_{2} static gauge field and three species of either gapless (Dirac) or gapped (chiral) Majorana fermionic excitations. We find that, when a magnetic field is applied to a zigzag edge, the Dirac KSL exhibits a nonlocal magnetization associated with the existence of zeroenergy edge modes. The application of a spin bias V=μ_{↑} μ_{↓} at the interface of the spin system with a normal metal produces a spin current into the KSL, which depends, in the zerotemperature limit, as a powerlaw on V for both Dirac and chiral KSLs, but with different exponents. Lastly, we study the longitudinal spin Seebeck effect, in which a spin current is driven by the combined action of a magnetic field perpendicular to the plane of the honeycomb lattice and a thermal gradient at the interface of the KSL with a metal. Our results suggest that edge magnetization and spin transport can be used to probe the existence of chargeneutral edge states in quantum spin liquids. 

G70.00194: Magnetic impurity bands in Gax−1MnxS: Towards understanding the anomalous spinglass transition Thomas Pekarek, M.C. Massey, I. Manuel, Paul S. Edwards, D. Parker, Jason Haraldsen We report on magnetic and electronic properties of a quasi2D singlecrystalline Ga0.91Mn0.09S diluted magnetic semiconductor (DMS) that shows an anomalously high spinglass Tc at 11.2 K. Using density functional theory (DFT), we characterize the properties contributing to the spinglass transition through an examination of electronic and magnetic properties for Ga1−xMnxS (0<x<0.18). The Mn produces impurity bands in the electronic structure, where an analysis of the density of states shows an increase in magnetic impurity bands at the Fermi level that lowers the semiconducting gap consistent with DMS. This is similar to other DMS, where the primary mechanism is likely through magnetic exchange. The increased electron density with Mn doping could explain the anomalously higher Tc in Ga0.91Mn0.09S. In comparison with the substantially lower transition temperatures in related IIVI based systems (e.g., Zn1−xMnxTe), the high Tc is associated with more metallic spinglass systems that interact through RKKY exchange, which leads to the conclusion that there may be a combination of interactions occurring in these systems. 

G70.00195: Spin pumping driven by magnonphonon coupled mode Hiroki Hayashi, Kazuya Ando The properties of magnons and phonons, quasiparticles of spin waves and acoustic waves, have been investigated independently for more than half a century. However, the interaction between magnons and phonons can arise from spinorbit, dipoledipole, and exchange interactions in magnetic crystals. The coupling strength is most enhanced in the proximity of the intersection of the uncoupled magnon and phonon dispersions. In the coupling region, the quasiparticle with admixtures of both magnetic and elastic properties, magnonpolarons, is formed. 

G70.00196: Computing dynamic spin structure factor using matrix product state method and the time dependent variational principle Ling Wang We demonstrate that matrix product state combined with the time dependent variational principle can accurately reproduce a real time evolution of a disturbed ground state. From real time correlation of spin operators respect to the ground state, we compute the dynamic spin structure factor. We will show benchmark results for 1d Heisenberg chain, as well as extensive calculations on 2d square lattice Heisenberg model. 

G70.00197: Critical behavior of the layered ferromagnet Fe_{1/4}TaS_{2} Chenhui Zhang, Ye Yuan, Yan Wen, Xixiang Zhang The critical behavior of singlecrystalline layered ferromagnet Fe_{1/4}TaS_{2} were studied by bulk dc magnetization around the paramagnetic to ferromagnetic phase transition. Critical exponents β = 0.459(6) and γ = 1.205(11) are extracted from the KouvelFisher plot, whereas δ = 3.69(1) is obtained by the critical isotherm analysis at T_{c} = 100.7 K. These critical exponents obey the Widom scaling relation δ=1+γ/β. Moreover, the selfconsistency and reliability of the results are further verified by scaling equations. The determined exponents match well with those calculated from the results of renormalization group approach, and our analysis suggests that Fe_{1/4}TaS_{2} possesses threedimensional longrange magnetic interactions with the exchange distance decaying as J(r) ≈ r^{−4.8}. 

G70.00198: Alloptical Control of the Magnetization in EuS, a Versatile Magnetic Insulator Andre Henriques, Xavier Gratens, Pavel Usachev, Valmir Chitta, Yunbo Ou, Jagadeesh Moodera Finding new mechanisms of alloptical control of the magnetic state of matter is highly sought for the development of new devices and for optic based quantum computing. Recently we demonstrated that a single incident photon can generate several thousand spin coherent electrons in antiferromagnetic EuSe, by forming a supergiant spin polaron [1]. Because of the gigantic magnetic moment of the spin polaron, a tiny magnetic field can induce coherence in the spin polaron ensemble. 

G70.00199: Hybrid quantumclassical method for simulating spinspin relaxation in solidstate NMR. Grigory Starkov, Boris Fine We propose a new hybrid quantumclassical method for firstprinciples calculations of NMR free induction decay (FID) in solids where spin1/2 nuclei form periodic lattices. The method is based on the simulations of a finite cluster of spins 1/2 coupled to an environment of interacting classical spins via a correlationpreserving scheme. Such simulations are shown to lead to accurate FID predictions for one, two and threedimensional lattices with a broad variety of interactions. The accuracy of these predictions can be efficiently estimated by varying the size of quantum clusters used in the simulations. 

G70.00200: Prediction of intrinsic properties of Fedoped CeCo_{5} Durga Paudyal, Renu Choudhary Due to high uniaxial anisotropy and abundant nature of Ce, CeCo_{5} has become a subject of intense research for getting an excellent permanent magnet with low cost. CeCo_{5} comes under the materials having a crystal structure of CaCu_{5}type with space group P6/mmm. The changes in the valence state of the Ce atom from +4 to +3 due to the presence of Cu in CeCo_{5} can enhance the coercivity of CeCo_{5x}Cu_{x}. The replacement of Coatom by another transition metal can manipulate the magnetization. The first principles calculations were performed to study the effect of Fedoping on the magnetic properties of CeCo_{4.5x}Fe_{x}Cu_{0.5} to increase the magnetic moment with sufficient anisotropy. Fe doping increases the total moment. The anisotropy is highly dependent on the sites occupied by Fe and Cu. 20% Fe gives high uniaxial anisotropy in CeCo_{4.5x}Fe_{x}Cu_{0.5} for Cu at the 3g site, whereas 10% Fe in CeCo_{4.5x}Fe_{x}Cu_{0.5} gives high uniaxial anisotropy for Cu at the 2c. Site preference of Fe is also checked for the compounds separately with Cu at 2c and 3g sites. Depending upon the concentration, Fe prefers both 3g and 2c sites in a CeCo_{4.5x}Fe_{x}Cu_{0.5 }indicating the importance of the structural geometry. 

G70.00201: WITHDRAWN ABSTRACT


G70.00202: New roots for synthesis of Cobalt carbide nanoparticles for rare earth free permanent magnets Eduardo MartínezTerán, Ahmed ElGendy Magnets have made a great impact in our daily lives, since they are present in all kind of modern devices. However, one of the problems we may encounter in near future is that the supply of materials from which the magnets are made, rare earths, may not be able to supply their demand. In addition, the usual production of magnets involves many steps in between, the melting of raw materials, mold casting, cooling, crushing and then pressing them into the desired shape. For those reasons, we propose the creation of permanent magnets from abundant materials, Cobalt and Carbon. Therefore, we propose synthesis of CoxC nanoparticles using super critical conditions (pressure and temperature). The materials precursors are mixed with solvent and heated up to its supercritical conditions where it decomposes to nanoscaled particles in powder shape, ready for being pressed. The morphology and phase structure were characterized using SEM and XRD to reveal cylindrical like shape and Co_{x}C orthorhombic phase structure respectively. The magnetic properties have been measured to yeild coercivity (Hc) of 760 Oe with saturation magnetization (Ms) of 37.41 emu/g, with an energy product of 2.84 MGOe. This method is still under optimization to reach the single phase of Co3C with higher Hc and Ms. 

G70.00203: Structural, magnetic, magnetodielectric and electronic structure study of Mn_{1.5}Cr_{1.5}O_{4} Gopeshwar Dhar Dwivedi, Hsiung Chou, K. W. Liu, B. Y. Chen, D Chandrasekhar Kakarla, Amish. G. Joshi Cr substituted Mn_{3}O_{4} exhibited increased Néel temperature along with structural transition from tetragonally distorted Mn_{3}O_{4} (x=0.00) to cubic Mn_{1.5}Cr_{1.5}O_{4} (x=0.50). Mn_{1.5}Cr_{1.5}O_{4} exhibits a dielectric anomaly around magnetic transition temperature which suggests that magnetodielectric coupling is still present in this cubic system. Lowtemperature Xray diffraction pattern of Mn_{1.5}Cr_{1.5}O_{4 }at 20 K has confirmed the absence of structural transition below T_{N}. The observed magnetodielectric effect in Mn_{1.5}Cr_{1.5}O_{4 }indicates that MD effect has been diminished in comparison to Mn_{3}O_{4}. Xray photoemission spectra and Xray absorption nearedge structure (XANES) confirms that Cr exists at the octahedral site with +3 oxidation state. Extended Xray absorption fine structure (EXAFS) indicates increased shortrange ordering in Mn_{1.5}Cr_{1.5}O_{4} which could be a key factor for this increase in T_{N}. 

G70.00204: Twoion magnetocrystalline anisotropy using maximally localized Wannier functions Liqin Ke, Bruce Harmon Using an ab initio tightbinding Hamiltonian based on maximally localized Wannier functions, we investigate the twoion magnetocrystalline anisotropy in L1_{0}type transition metal compounds such as FePt and FeNi. This method can accurately calculate the MAE over the whole bandfilling range. The smaller basis set allows us to efficiently resolve MAE with a very high resolution in reciprocal space. The kresolved MAE using the force theorem and perturbation theory agree well with each other, both reflecting the aspects of the Fermi surface. We resolve MAE into intrasublattice and intersublattice contributions using both perturbation and scaling procedures, and agreement between them is excellent. Thus this realistic tightbinding method provides an effective approach to describe and analyze MAE. Once the realspace Hamiltonian is constructed, this approach is orders of magnitude faster than the corresponding first principles techniques, but with very similar accuracy. 

G70.00205: Suppression of spincrossover by dynamic JahnTeller effect in C_{60}^{3} Naoya Iwahara, Dan Liu, Liviu F Chibotaru In conventional spin crossover systems, the vibrational degrees of freedom enhances the entropic effect in excited highspin terms resulting from the softening of vibrations [1]. Here, we show an opposite effect of vibration on the spincrossover taking C_{60}^{3} as an example [2]. C_{60}^{3} anion takes either high (S = 3/2) or low (S = 1/2) spin state, and in the latter the dynamical JahnTeller effect arises. It is found that the large dynamical JahnTeller stabilization energy lowers the lowspin levels, resulting in the violation of Hund’s rule. The JahnTeller dynamics influences the thermodynamic properties via strong variation of the density of vibronic states with energy. Thus, the large vibronic entropy in the lowspin states enhances the effective spin gap of C_{60}^{3} quenching the spin crossover. This finding is used for the rationalization of the experimental data on the spin gaps in various fullerides. The vibronic mechanism is not limited to fullerene: It can play a crucial role when Hund and JahnTeller couplings are comparable to each other. 

G70.00206: Unconventional magnetic anisotropy in onedimensional Rashba system realized by adsorbing Gd atom on zigzag graphene nanoribbons Zhenzhen Qin, Guangzhao Qin, Bin Shao, Xu Zuo The Rashba effect, a spin splitting in electronic band structures, attracts much attention for potential applications in spintronics with no requirement of an external magnetic field. Realizing a onedimensional (1D) Rashba system is a big challenge due to the difficulties of growing highquality heavymetal nanowires, introducing strong spin–orbit coupling (SOC) and broken inversion symmetry. Based on firstprinciples calculations, we propose a pathway to realize the Rashba spinsplit by adsorbing Gd atom on zigzag graphene nanoribbons (GdZGNR) and further investigate the magnetic anisotropy energy (MAE). Perpendicular MAE and unconventional MAE contributions in kspace are found in the selfassembled GdZGNR system, which presents a remarkable Rashba effect (the estimated strength is 1.89 eV Å) due to the strong SOC and the asymmetric adsorption sites at the nanoribbon edge. Moreover, firstorder MAE is connected to the intrinsic Rashba effect beyond the traditional secondorder MAE. The dependence on the ribbon width of the firstorder MAE and the Rashba effect are also examined. This work not only opens a new gate for designing the 1D Rashba system but also provides insight into the unconventional MAE due to the intrinsic Rashba effect. 

G70.00207: A New Magnetic Material Leading to Airstable Twodimensional Magnets Xiaoyu Song, Shiming Lei, Sebastian Klemenz, YaoWen Yeh, Daniel Weber, Nan Yao, Leslie Schoop The emergence of high quality twodimensional(2D) intrinsic magnetic materials is of vital importance in the development of next generation’s functional devices^{[1]}. Over the past few years, several 2D magnets, such as VSe_{2}^{[2]}, MnSe_{2}^{[3]}and Fe_{3}GeTe_{2}^{[4, 5]}were discovered since the two breakthrough 2D magnets, CrI_{3}^{[6]}and Cr_{2}Ge_{2}Te_{6}^{[7]},mechanically exfoliated from their vanderWaals parent materials. However, none of the known 2D magnets are airstable, which limits their practical applications. 

G70.00208: Magnetic control over the inter atomic distance in atomic chains Sudipto Chakrabarti Typically, in nanoscale spintronics the structure of miniaturized and lowdimensional systems is designed to achieve magnetic functionality. Here, we present an opposite approach, where we use magnetic field to affect the structure of a nanoscale system. Specifically, we find that the interatomic distance in a suspended chain of platinum atoms in a breakjunction setup can be modified significantly by the direction and magnitude of an applied magnetic field. This effect leads to variations in the stability of the examined atomic chains and it is amplified in longer chains, in good agreement with theoretical models. Our findings open the door for atomistic understanding of magnetostriction, a central phenomenon with wide implications in science and technology. 

G70.00209: Point of Care Biosensor Platform for the Quantitation of Magnetic Lateral Flow Assays Mohammad Khodadadi, Long Chang, Dmitri Litvinov PointofCare (POC) diagnostic is currently the most accessible form of medical diagnosis because it is affordable, sensitive, specific, userfriendly, rapid/robust, equipmentfree/minimal, and distributable to those in need. In this work, we investigate a new inductionbased transducer designed around a lateral flow assay that is low cost, portable and enhances the sensitivity of the test by 100 times. 

G70.00210: Structural and magnetic properties of Co_{2x}Ti_{x}FeGe (0 ≤ x ≤ 1) alloy series with plausible halfmetallic behavior Shambhu KC We report the synthesis and characterization of a Co_{2x}Ti_{x}FeGe (0 ≤ x ≤ 1) alloy series by substituting Co with Ti atoms in a stoichiometric Co_{2}FeGe alloy. Based on prior microscopic and structural characterization, Co_{2}FeGe is reported not to be phase pure^{1}. By Ti substitution, however, we investigated and found singlephase behavior for 0.375 ≤ x ≤ 0.875, while the other composition studied showed multiphase behavior, supporting previous work. XRD analysis reveals cubic crystal structure for all singlephase samples with the lattice parameter increasing almost linearly with increasing Ti substitution. The extracted magnetic moments at 5 K show strong agreement with the SlaterPauling moments. 

G70.00211: Lowdamping magnetic materials in FMNMFM structures on flexible substrates for RF/microwave applications Xinjun Wang, Ivan Lisenkov, NianXiang Sun, Katie Hauck, Kevin Walker New magnetic materials can open a way for energyefficient and flexible antenna and RF microwave devices. Low damping magnetic materials have been attributed to singlecrystal magnetic insulators. Highquality with low damping magnetic materials, are deposited on flexible substrates, are needed to enhance the performance of flexible devices. Here, we demonstrated low magnetic damping in a ferromagnetic (FM)/nonmagnetic(NM)/ferromagnetic(FM) structure fabricated on a flexible Mica substrate, which comparable with the one found in solid structures. With different Ru thickness, the two FM layers shows parallel(P) and antiparallel(AP) interaction, which is called the Ruderman–Kittel–Kasuya–Yosida (RKKY) interaction. For an AP coupling, the linewidth demonstrates a different behavior. For low external fields (and low frequencies in the range 4GHz – 6GHz) the linewidth is practically independent with the frequency, which shows great potential applications for RF/microwave devices and antenna. 

G70.00212: Tuning structural and magnetic properties by vanadium substitution in Fe_{3}Ge Rabin Mahat The structural and magnetic properties of Fe_{3x}V_{x}Ge intermetallic alloy series (0<x≤1) have been investigated. The samples were prepared by arcmelting under argon atmosphere. After annealing, alloys with 0.375≤x≤0.625 are found to crystallize in the cubic Heusler structure, while alloys with 0<x≤0.25 crystallize in the hexagonal DO_{19, }which is the high temperature phase of parent Fe_{3}Ge. Optical microscopy, EDX, and XRD reveal uniform granular microstructures for x≤0.75.The calculated lattice parameter increases linearly with increasing x, while the magnetic moment at 5K decreases linearly for cubic alloys, deviating only about 7% from the SlaterPauling values, which indicates possible halfmetallic behavior. The hexagonal samples have markedly higher moments. The saturation magnetizing field is found to decrease with the increase of x making the system softer at higher V concentrations.The martensitic phase transformation in all stable cubic phases is confirmed by DSC which is being reported for the first time for this system. Vanadium is found to play a crucial role in stabilizing the cubic structure and shifting the martensitic transformation temperature to higher values from that of parent Fe_{3}Ge. 

G70.00213: The SSRL BL13 Scanning Transmission Xray Microscopy for the Study of Magnetic Materials Hendrik Ohldag Today’s magnetic device technology is based on complex magnetic alloys or multilayers that are patterned at the nanoscale and operate at gigahertz frequencies. To better understand the behavior of such devices one needs an experimental approach that is capable of detecting magnetization with nanometer and picosecond sensitivity. In addition, since devices contain different magnetic elements, a technique is needed that provides elementspecific information about not only ferromagnetic but antiferromagnetic materials as well. Synchrotron based Xray microscopy provides exactly these capabilities because a synchrotron produces tunable and fully polarized Xrays In this contribution we will present the capabilities of synchrotron based Xray microscopy, which is becoming a tool available at every synchrotron. The particular capabilties of the instrument discussed here is the ability to detect very small changes in the magnetization induced by external stimuli like curretns or fields. It also allows to follow magnetization dynamics with a time resolution of the order of 10 ps. We will show results that demonstrate the ability to image spin waves, electric field induced changes in antiferromagnets as well as spin accumulation in nonmagnets. 

G70.00214: MagnetoRaman Spectroscopy on Vanadiumderived Lacunar Spinel GaV_{4}S_{8} Calvert Barclay, D. Ologunaguba, Zhengguang Lu, Ganesh Pokharel, Hasitha Suriya Arachchige, Andrew D Christianson, David Mandrus, Dmitry Smirnov, Komalavalli Thirunavukkuarasu Chalcogenides with the GaM_{4}S_{8} structure are hetero cubane like [M_{4}X_{4}]^{n}^{+} cubes (M = Mo, Re,V, Nb, Ta; X = S, Se, Te) and [AX_{4}]^{n}^{} tetrahedra (A= Ga, Ge), these adopt the NaCl structure[1,2]. GaV_{4}S_{8 }is a known Mott insulator because of the long intercluster distances approximately 4 Å apart [1]. GaV_{4}S_{8} (GaVS) is a magnetic semiconductor with a Neeltype skyrmion phase displaying multiferroic properties [3]. Magnetic susceptibility measurements showed structural transition at T_{JT }of 42 K followed by a ferromagnetic order at 12 K [4] and 12.7 K [5]. Temperaturedependent infrared and Raman measurements identified phonon modes and JahnTeller distortions [6]. For detailed information on the various exchange interactions in GaV_{4}S_{8}, we performed magnetoRaman measurements at magnetic fields up to 20 T and temperatures down to 5 K. 

G70.00215: Characterization of microstructure and residual stresses using Barkhausen noise measurements Neelam Prabhu Gaunkar, Gajanana Prabhu Gaunkar, David C Jiles Micromagnetic measurement methods based on Barkhausen Noise (BN) measurements are increasingly being used as a versatile and cost effective tool for insitu examination and evaluation of microstructural changes. They are also used for measurement of surface residual stresses. Interpretation of the observations and measurements, however, require validation with the help of appropriate calibration procedures. 

G70.00216: ATOMIC, MOLECULAR, AND OPTICAL (AMO) PHYSICS


G70.00217: Dynamics of a 2D disordered dipolar interacting spin ensemble on the surface of diamond Kristine Rezai, Phillip E Weinberg, Soonwon Choi, Mikhail Lukin, Alexander Sushkov Statistical mechanics has long been the framework which connects the microscopic world to macroscopic observables. However, its fundamental assumption has been shown to break down in a class of strongly disordered systems, resulting in a slowdown or absence of thermalization. In this work, we use a shallow nitrogenvacancy center to probe the dynamics of disordered dipolar interacting electronic spin1/2 defects on the diamond surface. Using magnetic resonance techniques, we characterize and control the strength of disorder and dipolar interactions among the electronic spins. We measure the autocorrelation of individual spin projection, which exhibits a decay on a time scale much slower than the inverse interaction strength, indicating a substantial slowdown of thermalization. 

G70.00218: Exploring quantum correlations in a manybody localized system Julian Leonard, Matthew Rispoli, Alexander Lukin, Robert Schittko, Sooshin Kim, Joyce Kwan, Markus Greiner An interacting quantum system that is subject to disorder may cease to thermalize due to localization of its constituents, thereby marking the breakdown of thermodynamics. We realize such a manybodylocalized system in a disordered BoseHubbard chain and characterize its entanglement properties through particle fluctuations and correlations. 

G70.00219: Optical blackhole analog in inhomogeneous photonic lattice Meng Kang, Huaqing Huang, Hongxing Xu, Feng Liu Hawking radiation, a key to quantum gravity, has stimulated extensive theoretical and experimental studies of various blackhole analogs. Here we theoretically develop a new laboratory analog of black hole in an inhomogeneous twodimensional graphynelike topological photonic lattice. A predesigned lattice transition from typeII to typeI Dirac cone creates an analogous curved space time crossing the event horizon (typeIII Dirac cone). Photons tunneling through the horizon emit a spectrum of Hawking radiation with a Hawking temperature of 14 μK. Our approach provides a universal design for the optical blackhole analogs in topological photonic crystals and metamaterials. 

G70.00220: Coherent coupling of fluctuations in mesoscopic systems in optomechanics Devender Garg, Asoka Biswas Interaction between a quantum and a mesoscopic system has always been intriguing in understanding the quantumclassical interface. In this context, we show how the energy fluctuations can be adiabatically exchanged, by using laser pulses, between two mirrors or between the motional degree of freedom of an ion trapped inside the cavity and that of one of the cavity mirrors. In the former case, two membranes are suspended inside a cavity. The zeroeigenvalue eigenstate of the matrix governing their fluctuation dynamics indicates that a suitable sequence of pulses to drive the cavity modes can lead to a deterministic adiabatic transfer of energy fluctuations from one membrane to the other, in a way akin to stimulated Raman adiabatic passage. Similar results can also be obtained in the later setup, in which a single ion is trapped inside an optical cavity, with one of the mirrors oscillating. Our results show that it is possible to coherently couple the fluctuations of two mesoscopic systems. Interestingly, this also indicates that the motion of a trapped ion (a quantum system) can lead to motional fluctuation in a mesoscopic mirror. This opens up possibilities for an ioncontrolled longdistance transfer of fluctuations among mirrors, using more cavities. 

G70.00221: Anyonic statistics of quantum impurities in two dimensions Enderalp Yakaboylu, Mikhail Lemeshko We demonstrate that identical impurities immersed in a twodimensional manyparticle bath can be viewed as fluxtubechargedparticle composites described by fractional statistics. In particular, we find that the bath manifests itself as an external magnetic flux tube with respect to the impurities, and hence the timereversal symmetry is broken for the effective Hamiltonian describing the impurities. The emerging flux tube acts as a statistical gauge field after a certain critical coupling. This critical coupling corresponds to the intersection point between the quasiparticle state and the phonon wing, where the angular momentum is transferred from the impurity to the bath. This amounts to a novel configuration with emerging anyons. The proposed setup paves the way to realizing anyons using electrons interacting with superfluid helium or lattice phonons, as well as using atomic impurities in ultracold gases [1]. 

G70.00222: ABSTRACT WITHDRAWN


G70.00223: Emergent Floquet prethermalization signatures in outoftime ordered correlations Pai Peng, Xuan Wei, Oles Shtanko, Iman Marvian, Chandrasekhar Ramanathan, Seth Lloyd, Paola Cappellaro How a manybody quantum system thermalizes or fails to do so under its own interaction is a fundamental yet elusive concept. Here we demonstrate nuclear magnetic resonance observation of the emergence of prethermalization by measuring outoftime ordered correlations. We exploit Hamiltonian engineering techniques to tune the strength of spinspin interactions and of a transverse magnetic field in a spin chain system, as well as to invert the Hamiltonian sign to reveal outoftime ordered correlations. At large fields, we observe an emergent conserved quantity due to prethermalization, which can be revealed by an early saturation of correlations. Our experiment not only demonstrates a new protocol to measure outoftime ordered correlations, but also provides new insights in the study of quantum thermaldynamics. 

G70.00224: Rebuilding of destroyed spin squeezing in noisy environments Peng Xu We investigate the process of spin squeezing in a ferromagnetic dipolar spin1 BoseEinstein condensate under the driven oneaxis twisting scheme, with emphasis on the detrimental efect of noisy environments (stray magnetic felds) which completely destroy the spin squeezing. By applying concatenated dynamical decoupling pulse sequences with a moderate bias magnetic feld to suppress the efect of the noisy environments, we faithfully reconstruct the spin squeezing process under realistic experimental conditions. Our noiseresistant method is ready to be employed to generate the spin squeezed state in a dipolar spin1 BoseEinstein condensate and paves a feasible way to the Heisenberglimit quantum metrology. 

G70.00225: On Local Simulations of Local Fluxes in Molecular Juncitons Gabriel Cabra, Anders Westergaard Jensen, Michael Galperin, Massimiliano Di Ventra We present a pedagogical review of the current density simulation in molecular junction models indicating its advantages and deficiencies in the analysis of local junction transport characteristics. In particular, we argue that current density is a universal tool which provides more information than traditionally simulated bond currents, especially when discussing inelastic processes. On the other hand, current density simulations are sensitive to the basis set and the electronic structure method utilized. We note that while discussing the local current conservation in junctions, one has to account for the source term caused by the open character of the system and intramolecular interactions. Our considerations are illustrated with numerical simulations of a benzenedithiol molecular junction. 

G70.00226: Solution of the independent boson model with quadratic coupling Aurelia Chenu, ShiueYuan Shiau, Monique Combescot We revisit the model of a twolevel system coupled to phonons, and provide analytical solutions including a quadratic coupling, which was until now unsolved. Indeed, current techniques to analytically solve this important problem, like the polaron transformation which eliminates what is commonly called systemphonon couplings, hide the fundamental physics. These couplings can be eliminated using a diagonal basis, in which phonons depend on the electronic level. Doing so, we obtain analytical results through a simple algebra, by switching back and forth from groundphonons to excitedphonons. We easily recover standard results for linear coupling, like state dynamics and correlation functions for absorption/emission lineshapes, in a way far simpler than previous procedures. More importantly, we find solution for the Hamiltonian including quadratic coupling, for which no analytical results have been reported yet. This approach opens a conceptually new route to more complicated matterboson systems. 

G70.00227: A Quantum Mechanical Study of Francium and Radium Clusters David Nunn, Ajit Hira, Jose Pacheco, Jareth Baca This report presents our research on the small atomic clusters of francium (Fr_{n}), and radium Ra_{n} (n = 19), and their hybrids Fr_{n}Ra_{n} clusters. Francium is a heavy, unstable, radioactive metal with a maximum halflife of only 22 minutes. Radium is the heaviest and most reactive element of the alkaline earth metals family. Hybrid ab initio methods of quantum chemistry (particularly the DFTB3LYP model) were used to derive optimal geometries for the clusters of interest. We compare calculated binding energies, bondlengths, ionization potentials, electron affinities and HOMOLUMO gaps for these clusters.The theoretical study of Fr_{n} clusters, such as ours, is particularly important because very little experimental data is available on its physical properties. It is interesting to check the stability of francium in cluster form. The interactions of Fr_{n} clusters with O atoms, O_{2} molecules, H_{2}O molecules, and with some C_{n} clusters will be compared to similar interactions for Ra_{n} clusters. The possible implications of our computational results for the roles of Radium and Francium as cancercausing materials will be examined. 

G70.00228: Developments in quantum dynamics of fulldimensional diatomdiatom collisions at preexascale Benhui Yang, Yier Wan, Phillip Stancil, Balakrishnan Naduvalath, Robert C Forrey Accurate rate coefficients for molecular rovibrational transitions due to collisions with H_{2} are critical for interpreting IR astronomical observations. Theoretical results are the primary source of such rate coefficients. The most accurate theoretical approach is the quantum closecoupling method. Recently we extended fulldimensional quantum dynamics calculations of rovibrationally inelastic scattering large systems including COH_{2}, CNH_{2}, SiOH_{2,} and CSH_{2}. The rovibrational cross sections have been computed using various implementations of the TwoBC code based on 6D potential energy surfaces. To date, fullD scattering calculations are mainly focused on the target molecule in its ground and first excited vibrational states with H_{2} treated as a rigid rotor. To perform scattering computations with larger vibrational excitation of both diatoms further increases the computational demands. This relies on the availability of leadershipclass computational resources. We present preliminary results for rovibrational scattering computations on Titan, SummitDev, and Summit with a progression 

G70.00229: Multidimensional BinWidth Optimization for Histogram and Its Application to FourDimensional Neutron Inelastic Scattering Data Kensuke Muto, Hirotaka Sakamoto, Keisuke Matsuura, Takahisa Arima, Masato Okada We propose a method for optimizing bin widths for multidimensional We propose a method for optimizing bin widths for multidimensional histograms. In recent years, a large amount of fourdimensional event data has been obtainable in neutron inelastic scattering experiments conducted by chopper spectrometers[1]. As preprocessing, researchers make histograms from obtained event data. At present, the researchers only empirically select bin widths and slice conditions to get a twodimensional histogram, while checking the histogram in a visual approach[2]. We propose a method which can automatically make a multidimensional histogram from event data. Our method was derived from the onedimensional bin width optimization method[3]. In this paper, we use artificial data to investigate the behavior of our method. We applied the proposed method to both sliced twodimensional event data and the whole fourdimensional event data. Comparing their results, we have found that the optimized binwidth strongly depends on the dimensionality of the data. Moreover, the optimum bin widths are affected by the number of events and the magnitude of the white background noise. 

G70.00230: Diffusion of carbon adatoms on gold ion trap electrode surfaces Hossein Jooya, Kyle S. McKay, Eunja Kim, Phil Weck, David Pappas, Dustin A Hite, Hossein Sadeghpour In ion traps, the electric field noise emanating from the trap electrodes remains as a major obstacle to the realization of iontrap based scalable quantum computing architectures. The source of this anomalous noise has been identified as the fluctuating surface adatom dipoles (mostly carbonbearing). The original microscopic theory of fluctuating surface dipoles is static. In order to provide a more realistic picture of the surface dynamics, the mobility of these dipoles whose magnitude change with motion on the electrode surface should also be considered. One of the unknown parameters in the electric field noise spectral power is the diffusion constant of such adsorbates. In this study, classical molecular dynamics (MD) simulations are used to calculate longtime diffusion constant and transition rates of carbon adatoms on various gold surface orientations. The resultant fluctuation in the induced dipole moment is then obtained by computing the work function of the surface, using the densityfunctional theory method. Such time domain calculations also provide us with a clear picture of carbon structure and cluster formation on various gold surfaces. 

G70.00231: Qubit lattice representation of PTsymmetric BEC subsystems Linda Vahala, George Martin Vahala, Connor Simpson, Abhay Ram, Min Soe PT invariant nonHermitian Hamiltonians have become an important class of problems that permit a wider family of solutions than their more familiar Hermitian counterparts. In particular dark or bright solitons in the Hermitian Nonlinear Schrodinger equation require either a defocusing or focusing potential. However in the fully integrable PT nonHermitian form it was shown that both dark and bright solitons can coexist simultaneously. Here we consider a qubit unitary representation of an open doublewell BEC interacting subsystem whose evolution is given by nonHermitian PT Hamiltonians [Wunner]. Under the usual Dirac inner product, this doublewell system is nonunitary. These subsytems can be embedded into a higherdimensional closed Hermitian system [Wunner] or used to perturbatively generate a Hermitian analog [Baraenskov]. A qubit unitary representation, with two qubits/lattice site for each scalar field, can now be generated. This give rise to an extremely parallelized algorithm that is not only ideal on classical supercomputers but readily coded onto a quantum computer because of its inherent unitarity. Quantum turbulence in such open PTBEC systems is considered. 

G70.00232: 3/2body correlations in the ground state of Bose–Einstein condensates Wataru Kohno, Akimitsu Kirikoshi, Takafumi Kita Recently, one of the author has been constructed a variational wave function, which describes weakly interacting BoseEinstein condensates (BECs) with dynamical 3/2body correlations, where one of the two colliding noncondensates drops into the condensate and visa versa. In this presentation, we apply the variational method to (1) Mcomponent BEC and (2) BEC trapped by a general trap to investigate the properties of 3/2body correlations in BECs more qualitatively. From our numerical results in both cases, the 3/2body correlations lower the groundstate energy in an amount comparable to the meanfield contribution. 

G70.00233: Quantum droplet in a mixture of RbNa BoseEinstein condensates Zhichao Guo, Fan Jia, Lintao Li, Dajun Wang According to the meanfield theory, an atomic BoseEinstein condensate (BEC) will collapse when the interaction between atoms is attractive. However, the mixture of two BECs with attractive interspecies interaction can be stabilized by the beyond meanfield LeeHuangYang correction in the format of selfbound quantum droplets. In this talk, I will present our progress in studying the heteronuclear quantum droplet with the double BEC of Rb and Na atoms. With the help of an interspecies Feshbach resonance, we have created double BECs with nearly arbitrary interaction strengths and signs. This should allow us to cover the full phase diagram from two miscible or phase separated condensates, collapsing, and the droplet. 

G70.00234: Ultrafast twinpeak rogue waves in a vector field Moti Fridman, Hadar Steinberg Rogue waves, which were first discovered in the ocean, constitute an important factor in the dynamics of many physical systems. However, while the ocean can be represented by a scalar field, many physical systems, specifically in optics, are situated on a vector field, and thus, there are several crucial differences which must be considered. For example, twinpeak rogue waves are rare events in the ocean but are commonly observed in optics. We developed a model presenting the differences between the scalar field and the vector field. We show that optical twinpeak rogue waves have peaks with orthogonal states of polarization and measured such rogue waves in fiber lasers showing an agreement between our model and the measured results. This model, which can also be applied to other equivalent systems, explains the formation of rogue wave patterns in a vector field and their dynamics as a function of time. 

G70.00235: Ground State Properties for a Bose Gas Within a Periodic, MultiRods Structure Omar Abel RodríguezLópez, Miguel Solis We calculate the ground state (gs) energy and the static structure factor at zero temperature of an interacting Bose gas confined by a onedimensional, periodic, multirods structure created by an external KronigPenney potential. We employ the Diffusion Monte Carlo (DMC) method to solve the Schrödinger equation exactly up to a statistical error. The gs energy is compared with the results previously obtained using the Variational Monte Carlo method (VMC), as well with the results obtained using the MeanField theory approximation by solving analytically the GrossPitaevskii equation. In the limit of zero external potential, we recover the results for the wellknown LiebLiniger model [1]. For nonzero external potential, we find a phase transition from the superfluid state to a Mott insulator state as the lattice height increases. [1] E. H. Lieb and W. Liniger, Phys. Rev. 130, 1605 (1963). 

G70.00236: Magnetic model for supersolidity José MartínezHerrera, Miguel Solis The well known correspondence between the lattice liquid (or solid) model and a magnetic model like the Ising model, is used to obtain the thermodynamic properties of an onedimensional quantum crystal whose lattice is divided in two different interpenetrating sublattices α and β. Among others, we introduce a BoseEinstein condensation and an orderdisorder parameters to solve the equilibrium state. Then, we calculate the Helmholtz free energy in a mean field theory approximation and, applying the standard minimization method respect to the condensate and orderdisorder parameters, we find a critical temperature different from zero at which the system presents a phase transition like the BoseEinstein condensation which we connect with the possibility of a supersolid transition. 

G70.00237: Chiral Majorana edge states in the vortex core of a $p+ip$ Fermi superfluid Jing Bo Wang We study Majorana modes in the vortex core of a twodimensional $p+ip$ Fermi superfluid interacting with a BoseEinstein condensate. Under a repulsive $s$wave contact interaction between fermions and bosons, fermions are depleted from the vortex core when the bosonic density becomes sufficiently large. This gives rise to a dynamicallydriven local interface emerges between fermions and bosons, along which chiral Majorana edge states should appear. We examine in detail the variation of vortexcore structures as well as the formation of chiral Majorana edge states with increasing bosonic density, where the circulation of the vortex plays an important role. Whereas both the Majorana modes and vortexcore structures can be controlled and manipulated by tuning the bosonic density and the BoseFermi interaction strength, our study presents an illuminating example on how topological defects can be dynamically controlled in the context of cold atomic gases. 

G70.00238: Ultracold dysprosium for quantum simulation Pierre Barral, Michael A Cantara, Li Du, Willian Lunden, Alan Jamison, Wolfgang Ketterle Dysprosium is in many respects an atom of interest for quantum simulation. Its large angular momentum (J=8) in the ground state gives rise to one of the highest magnetic moments (10 Bohr magneton) in the periodic table, and one can therefore simulate an extended version of the Hubbard model with dipoledipole interactions. This large angular momentum combined with narrow transitions also allows one to implement strong atomlight coupling with reduced heating. It opens the way to create gauge fields, e.g., spinorbit coupling. We will report the most recent progress in our dysprosium apparatus. 

G70.00239: Onedimensional Bose polarons beyond the Fröhlich paradigm: localized impurities Hong Ling, Ben Kain Grusdt et al. [New J. Phys. 19, 103035 (2017)] recently made a renormalization group study of a onedimensional (1D) Bose polaron in cold atoms that goes beyond the usual Fröhlich description. We study the same model in the localized impurity limit where the ground state is described by a multimode squeezed state instead of the multimode coherent state in the static Fröhlich model. We solve the system exactly by applying the generalized Bogoliubov transformation, an approach that can be straightforwardly adapted to higher dimensions. Using our exact solution, we obtain a polaron energy free of infrared divergences and construct analytically the polaron phase diagram. We find the repulsive polaron is stable on the positive side of the impurityboson interaction but is always thermodynamically unstable on the negative side of the impurityboson interaction, featuring a bound state, whose binding energy we obtain analytically. We find the attractive polaron is always dynamically unstable, featuring a pair of imaginary energies which we obtain analytically. 

G70.00240: ABSTRACT WITHDRAWN


G70.00241: Quantum Simulation of the FermiHubbard Model Geoffrey Ji, Christie S Chiu, Annabelle Bohrdt, Muqing Xu, Justus Brüggenjürgen, Michael Knap, Eugene Demler, Fabian Grusdt, Markus Greiner, Daniel Greif Developments in quantum gas microscopy have enabled detailed studies of the repulsive FermiHubbard model. Using fermionic Lithium6 in a square lattice, we observe the transition into an antiferromagnet at temperatures below the superexchange energy. We use a novel patternfinding algorithm to characterize the system’s behavior upon holedoping. This new observable provides evidence that holes may be hiding the antiferromagnetic order rather than destroying it. We then investigate the deterministic injection of a single mobile dopant into an antiferromagnet and observe how it propagates. Finally, we discuss our progress towards an optical lattice with dynamically tunable interference contrast, which enables several lowentropy state preparation schemes and spinresolved readout. 

G70.00242: ^{6}Li in optical ring lattices Daniel Allman, Yanping Cai, Kevin Wright, Parth Sabharwal Optical ring lattices provide a convenient setting for studying, i.e., manybody correlations and emergent topological phenomena in lowentropy, lowtemperature Fermi ensembles. Due in part to technical challenges involved in creating and maintaining stable optical ring lattices, there has been no detailed experimental study of the behavior of fermions in periodic lattice geometries. We report on progress toward loading and trapping ^{6}Li atoms in optical ring lattices of ≤ 100 sites. By preparing lowentropy quantum states within the lattice, along with the ability to tune interactions with ^{6}Li's broad Feshbach resonance, we hope to observe a fermionic metaltoMott insulating transition in a strictly periodic geometry. We will also have the ability to investigate more exotic lattice structures, potential arenas for realizing several paradigmatic topological lattice models, such as the SuSchriefferHeeger model. 

G70.00243: Boosting the BEC critical temperature of an ideal Bose gas within a crystal with vacancies Juan Garcia, Miguel Solis, José MartínezHerrera We show that an ideal Bose gas in one or twodimensional imperfect crystal presents BoseEinstein condensation at a finite critical temperature, which does not happen when the crystal is perfect. For the threedimensional imperfect crystal case, the BEC critical temperature is higher than that of the gas in the perfect crystal. We have obtained the energy spectrum of the particles using the transfer and dispersion matrix methods as well as the use of the Green function, transfer matrix and dispersion, which we use to calculate, in addition to the critical temperature, the specific heat for the Bose gas within imperfect twodimensional structures such as multilines or grids, and for threedimensional cases such as multiplanes, multitubes and multicubes. 

G70.00244: Ultracold YbF molecules for measuring the electron's electric dipole moment Michael Trigatzis Theories that extend the Standard Model (SM) generally contain additional sources of CPviolation and predict the electron to have an electric dipole moment (eEDM) large enough to be measured by today's experiments. The eEDM may be measured by observing spin precession in YbF molecules in an electric field [1]. Recent results [14] already strongly constrain beyondSM theories. 

G70.00245: Progress towards quantifying the impacts of state mixing on the Rydberg excitation blockade Andrew Lesak, Aaron Whtye Reinhard Rydberg atoms are ideal for studying quantum phenomenon due to their exaggerated properties relative to groundstate atoms. During excitation, the highly polarizable atoms interact and the resonant frequencies of the atoms are shifted, leading to a suppression of excitation known as the “Rydberg excitation blockade.” In an ideal blockade, many atoms share one excitation and a more complete blockade is achieved when neighboring atoms interact more strongly. However, near a Forster resonance, stronger interactions can lead to the excitation of unwanted states, breaking the blockade. In order to implement scalable quantum computers, the Rydberg excitation blockade must be used in large samples and therefore statemixing properties must be rigorously studied in order to minimize their negative impacts. We laser cool rubidium atoms to microkelvin temperatures and use stateselective field ionization spectroscopy to determine the distribution of atoms in each Rydberg state. We present preliminary results in which we seek to quantify exactly how much statemixing reduces blockade efficiency and to determine the number of interacting bodies that lead to large amounts of statemixing. 

G70.00246: Twodimensional Condensation of Polar Molecules with Fieldinduced Dipoles IKang Liu, DawWei Wang, ShihChuan Gou We theoretically investigate the groundstate structures of a twodimensional condensation composed of ultracold polar molecules, in which the condensed particles are subjected to an effective vector potential induced by the Raman coupling between two rotational levels of the molecule. With all dipoles aligned by a DC field in the axial direction and the two counterpropagating Raman beams in the raidal direction, the effective dipole moment induced by the lightmatter coupling, which is much larger than the intrinsic dipole moment of the molecule, predominates the interaction between molecules. Based on the previous studies, the effective interaction features not only the standard longrange dipolar form but also a spatial dependence on the relative phase between two coupled rotational states. In the meanfield approximation, the ground state is found to possess four phases: planewave phase, zeromomentum phase and two of Stonertype phase. The first two phases appear when the system is in the couplingdominant regime, while the last two are in the interactiondominant regime. Numerical results obtained by solving the GrossPitaevskii equation agree with the variational analysis. Dynamical stability of the Stonertype phases is examined via calculating the Bogoliubov spectrum. 

G70.00247: Conclusive Precision Bounds for SU(1,1) Interferometers Chenglong You, Sushovit Adhikari, Xiaoping Ma, Masahide Sasaki, Masahiro Takeoka, Jonathan P Dowling We revisit the quantum Fisher information (QFI) calculation in SU(1,1) interferometer considering different phase configurations. Firstly, when one of the input modes is a vacuum state, we show by using phase averaging, different phase configurations give same QFI. In this case, the QFI is linearly proportional to the average photon number of the second input state, and quadratically proportional to the average photon number generated by the OPA. This suggests that when fixing the squeezing strength of the OPA, to achieve higher sensitivity, one simply needs to inject a state with higher average photon number. Secondly, we compared the results of the phaseaveraging method and the quantum Fisher information matrix method, and then we argued that for a SU(1,1) interferometer, phase averaging or quantum Fisher information matrix method is generally required, and they are essentially equivalent. Finally, we used the quantum Fisher information matrix method to calculate the precision limit for other common input states, such as two coherent state inputs or coherent state with squeezed vacuum inputs. 

G70.00248: Phase estimation in an SU(1,1) interferometer with displaced squeezed states Sushovit Adhikari, Narayan Bhusal, Chenglong You, Hwang Lee, Jonathan P Dowling We study the phase sensitivity of an SU(1,1) interferometer with coherent and displacedsqueezedvacuum (DSV) states as inputs, and parity and onoff as detection strategies. Our scheme with parity is subshotnoise limited and approaches the Heisenberg limit with increasing squeezing strength of the optical parametric amplifier (OPA). Also, for the onoff detection scheme, we show that subshotnoise sensitivity is possible by increasing the squeezing strength of the OPA. 

G70.00249: Threephoton molecule generation through coherent scattering process off single dipole emitter in quantum nanophotonics Zihao Chen, Yao Zhou, JungTsung Shen Bound state refers to the quantum state wherein wave function of constituent particles is localized, which typically require interactions between individual particles, e.g., two hydrogen atoms form bound state of a hydrogen molecule due to Coulomb interactions. Thus, photons do not form bound states (also called photonic molecules) easily due to its electric neutrality. Recently, it has been reported that, when three photons interact with a single emitter, photonphoton entanglement mediated by the emitter may induce the formation of 3photon molecules. However, the underlying generation mechanism is not yet clear. 

G70.00250: Towards Using Trapped Ions as Memory Nodes in a Photonmediated Quantum Network Jameson O'Reilly, Jackson Bell, Daniela Bogorin, Benjamin Bonenfant, Paul Cook, Savannah Decker, Lester Disney, Tyler Dolezal, Benjamin Driesen, Paige Haas, Nicholas Hougland, David Hucul, Brad Liu, Samuel Marthage, Brennal Nelson, Justin Phillips, Kaitlin Poole, Brandon Robinson, Harris RutbeckGoldman, Laura Wessing, KathyAnne Soderberg Quantum networking exploits features of quantum mechanics to provide ultrasecure networks that are both tamperproof and tamperevident. Such networks can be implemented as distant memory nodes connected via photonbased interfaces. Trapped ions are nearly ideal quantum network nodes due to the precise control possible over both their internal and external degrees of freedom as well as for their superior performance as longterm quantum memories. Photonbased qubits are the natural choice to transfer information within the network due to their ability to transmit quantum information over long distances and the capability to process information "onthefly" between the memory nodes. We present the quantum research being done at the Air Force Research Laboratory (AFRL) with a focus on trapped ion qubits, the short and longterm goals of the lab, and some of the unique resources we have access to at AFRL. Approved for Public Release [Case # 88ABW20182102] Distribution Unlimited. 

G70.00251: MESTSpacetime Center, Gluon, and New String Theory Dayong Cao MEST is a balance systemic model of mass, energy, space, and time. 

G70.00252: Cold Light of Bio Wave Change Four Kinds of PhotoVoltages at Same Changed Rate by Cold Photoelectric Effect Dayong Cao The thought waves remotely (wireless) simultaneous radiate to increase background photovoltages of the four solar cells at the same changed rates by cold photoelectric effect. 

G70.00253: Study on Stark broadening of low temperature He plasmas Wonwook Lee, Sungyong Shim, ChaHwan Oh Stark broadening is widely used to determine the electron density of the astrophysical plasmas and the atmospheric pressure plasmas. In low temperature plasmas Doppler broadening is larger than Stark broadening and the Stark broadening can be measured after removing Doppler broadening. In this research, the model for Stark broadening to determine the electron density was discussed in low temperature plasmas when Doppler broadening of plasma radiation was removed. The spectral line broadenings of van der Waals broadening, resonance broadening, natural broadening, and Stark broadening were calculated and compared with each other in low temperature He plasmas. As well the helicon plasma source of which electron density was higher than 10^{11}cm^{3} was constructed to investigate the helium Stark broadening. Stark broadening for 2^{1}S4^{1}P was measured using the saturation absorption spectroscopy and the electron density could be determined by analyzing the Stark broadening. 

G70.00254: Tracking innerholestate dynamics of complex atoms via doublecolor xray laster beams Yongqiang Li, Jiayu Dai, Xiaowei Wang, Zengxiu Zhao, Jianmin Yuan Both coherent pumping and energy relaxation play important roles in understanding physical processes of ultraintense coherent lightmatter interactions. Here, using a largescale quantum master equation approach [1], we describe dynamical processes of practical open quantum systems driven by both coherent and stochastic interactions. As examples, we investigate coherent dynamics of innershell electrons of a neon gas irradiated by a high intensity Xray laser along with vast number of decaying channels. In these singlephoton dominated processes, we find that, due to coherenceinduced Rabi oscillations and power broadening effects, the photon absorptions of a neon gas can be suppressed resulting in differences in ionization processes and final ionstage distributions. Second, we demonstrate a new scheme for the investigation of hole dynamics of complex atoms based on twocolor ultrashort Xray pulses. 

G70.00255: Multilevel selection rules of a Tunable Coupling Qubit KuanHsun Chiang, IoChun Hoi, YungFu Chen We study the level structure of a tunable coupling qubit (TCQ) [Ref. 1, 2] by microwave spectroscopy in superconducting circuit architecture. Based on the two independently tunable SQUID loops, the multilevel structure of a TCQ can be tuned insitu. We demonstrated that a TCQ is a charge qubit while providing tunable selection rule. Accompanied with the modetunability in coplanar waveguide design, Vtype, lambdatype and many other structures can be achieved in a TCQbased architecture. TCQs have potential for the application of microwave quantum optics. 

G70.00256: Static GrossPitaevskii equations for the molecular achiralchiral transitions Chong Ye, Quansheng Zhang, Yong Li In the meanfield theory, the stabilization of chiral molecules is understood as a quantum phase transition where the meanfield ground state of molecules changes from the achiral eigenstate of the molecular Hamiltonian to one of the degenerated chiral states due to the increase of the intermolecular interaction. However, the existing meanfield models are either unavailable to chiral molecules whose electric dipoles do not change in sign for L〉 and R〉 or with free parameters. In this work, starting from the Manybody Hamiltonian with electric dipoledipole interaction, we give the static GrossPitaevskii equations in the vibrational dimension. Our model can be applied to all chiral molecules and has no free parameters. 

G70.00257: Measurement of the He 2^{3}S state atom density in an inductively coupled Sungyong Shim, Wonwook Lee, ChaHwan Oh Helium 2^{3}S metastable atoms play key roles in discharge plasmas because of the long lifetime and large excitation energy. In this research, 2^{3}S state helium density in an inductively coupled plasma (ICP) was measured by laser absorption spectroscopy. He plasma was operated at the He pressure of 20~50 mTorr and by a RF power supply with the maximum power of 1.5 kW. Electron temperature and electron density of plasma were 2~3 eV and ~10^{12 }cm^{3}, respectively. Absorption spectra for the 2^{3}S_{1}>2^{3}P_{i} (i=0, 1, 2) transitions were measured by an external cavity laser diode (ECLD) at 1083 nm. The 2^{3}S state helium density was analysed and discussed with the RF power and the radial position in the plasma chamber. 

G70.00258: A Relativistic Conserved Current Subject to Constraints to Cancel Marginal Negative Probability Values James Boyle The bispinor solution to the Dirac equation is used to construct a conserved current. The possibility that the conserved current can take on marginal negative values is addressed as a condition that can be set and altered with constraints. Specifically, a Dirac bispinor solution is constructed and subject to constraints such that the marginal negative probability value in the corresponding conserved current is cancelled completely. Unexpectedly, and for a superposition of positive and negativeenergy states using these bispinor solutions, the conserved current derived here is shown to be completely absent of all Zitterbewegung terms. Various uses of the conserved current and the bispinor solutions derived here are also illustrated in conventional contexts, such as in computing scattering amplitudes across barrier potentials. 

G70.00259: Progress in an experiment to measure the electric dipole moment of the electron using YbF molecules Christopher Ho, Jack Devlin, Isabel M Rabey, Michael Tarbutt, Benjamin E Sauer, Edward A Hinds We report progress on an ongoing experiment to measure the electron EDM using YbF molecules [1]. 

G70.00260: Ultrafast Dynamics in Polythiophene Probed with Transient NEXAFS Spectroscopy Douglas Garratt A broad range of chemical reactions are triggered by the absorption of light. Examples include photosynthesis and charge transfer in semiconductors and molecules. Electronic dynamics which evolve on the few femtosecond to attosecond timescale are expected to play an important role in these processes. We aim to investigate these dynamics with transient Xray absorption near edge structure (XANES) spectroscopy. XANES spectroscopy uses resonant excitation of particular atoms in a molecule to provide a highly localised probe of electronic structure. By employing attosecond soft xray pulses generated via high harmonic generation for XANES spectroscopy this atomic scale spatial resolution can in principle be combined with the attosecond temporal resolution required for tracking electronic dynamics. I shall present development of a beamline for transient XANES spectroscopy and progress towards visible pump, soft xray probe experiments in the organic polymer poly(hexylthiophene). 

G70.00261: Realtime ESR lockin magnetic imaging with NVdiamond Matthew J Turner, Jennifer Schloss, Oren Ben Dor, Connor Hart, Yuan Zhu, Ronald L Walsworth Electron spin resonance (ESR) lockin sensing protocols with nitrogen vacancy (NV) centers in diamond allow for widefield, real time imaging of magnetic fields for biological applications ranging from biocurrent imaging to widefield tracking of magnetic nanoparticles. ESR lockin NV measurements have previously been utilized for the optical detection of firing action potentials in giant axons [1]. By modulating the applied microwave driving field and imaging the NV fluorescence with a specialized lockin camera, we are able to create real time videos of local magnetic fields with high spatial (~1 μm) and temporal (~1 ms) resolution over a large field of view (~1 mm). Here we show demonstrate a volumenormalized sensitivity of ~100 nT*μm^(3/2)*Hz^(−1/2) and compatibility with living biological systems. This work paves the way for the development of broadband quantum diamond microscopes for imaging biomagnetic fields from neuronal activity. 

G70.00262: Optimized microwave delivery structures for quantum diamond microscopes Yuan Zhu, Matthew J Turner, Raisa Trubko, Jennifer Schloss, Diana Prado Lopes Aude Craik, Ronald L Walsworth Magnetic field sensors and imagers employing nitrogen vacancy (NV) centers in diamond require strong, uniform microwave (MW) fields near 3 GHz. We present a new design for a planar waveguide structure fabricated on silicon carbide (SiC), which combines homogeneous microwave delivery with the heatspreading benefits of SiC. We perform finite element simulations in COMSOL, we fabricate and test MW structures, and we compare experimental performance with simulation results. We demonstrate optimized MW power delivery and improved MW field uniformity. We implement these MW delivery structures in quantum diamond microscopes (QDMs) to improve magnetic imaging performance in fields ranging from Earth and planetary sciences to biology. 

G70.00263: Scanning tunneling microscopy with infrared spectroscopy: recent findings. Kristopher Barr, Andrew I Guttentag, Paul S Weiss Surface scientists have used scanning tunneling microscopy (STM) to study the arrangement of molecularlevel structures for over thirty years. However, conventional STM images contain limited chemical information, restricting the scope of possible experiments. We extend the functionality of this instrument by combining the strengths of STM with infrared spectroscopy, producing images with both molecular resolution and chemical specificity. We backirradiated samples, illuminating the adsorbates evanescently. We selected multiplexed photon frequencies using an interferometer. Our model correlates the tunneling current to the vibrational signal. We image chemical structure with molecular resolution. This custombuilt instrument performs operates at ambient temperature and pressure, enabling us to run experiments on a variety of systems. 

G70.00264: Investigation of Single Photon Purity from Raman Processes Kai Shinbrough, Bin Fang, Yanting Teng, Yujie Zhang, Offir Cohen, Virginia O Lorenz Deterministic production of high purity photon states is essential for robust quantum communication and information applications. One way to implement the deterministic single photon production is the DuanLukinCiracZoller (DLCZ) protocol via phononmediated Raman processes. Although Raman processes have been well demonstrated, the purity of photons has remained largely unexplored. We investigate the effects experimental parameters have on the purity of single photons by using a phenomenological hamiltonian. We show how single photon purity depends on the length of the crystal and the bandwidth of the pump used to generate the photons. We compare our numerical simulations against experimental data showing qualitative agreement. 

G70.00265: Floquet Twoaxis Spinnematic Squeezing Lin Xin, Michael S Chapman Squeezing, which redistributes the quantum fluctuations between two noncommuting observables while preserving the minimum uncertainty product, has been extensively studied in boson systems. In addition, research in squeezed spin states (SSSs) is a topical area due to its significant applications in highprecision measurement and in quantum information science.The building block of spin squeezing is Oneaxis twisting (OAT). A twoaxis countertwisting mechanisms (TAT) is introduced as a natural extension of OAT and is shown to further reduce the quantum noise. So far, there are plenty of experiments that realized OAT while TAT haven't been achieved due to the experimental complexity. In this talk, I will present a way to produce TAT in spinnematic squeezed system by Floquet driving. Periodically microwave and radio frequency pulse sequence can adjust the direction of spin squeezing and thus generates an effective TAT Hamiltonian. By adapting this method, there is no need to change the setup of the apparatus, but instead, changes only the time sequence, improving the current experimental limit of spin squeezing. 

G70.00266: LASER SCIENCE


G70.00267: BesselBessel Laser Bullets Yousef Salamin Bessel beams carry orbital angular momentum (OAM). Opening up of the Hilbert space of OAM to information coding makes Bessel beams potential candidates for utility in data transfer and optical communications. The ultrashort and tightlyfocused analogue of a nondiffracting and nondispersing laser Bessel beam is often referred to as a laser bullet. Electromagnetic fields of a laser BesselBessel bullet are presented, following from solution to the wave equations of the scalar and vector potentials in the presence of an underdense plasma. Intensity distributions based on the derived fields are shown to propagate over many centimeters, without significant diffraction or distortion. The reported fields are derived, to lowest order, from a vector potential containing an ordinary Bessel function of arbitrary order and a zeroorder spherical Bessel function, hence the designation BesselBessel bullet. 

G70.00268: Supercontinuum generation with octavespanning bandwidth in the high order mode based Ta2O5 waveguide FuYan Yan, ChungLun Wu, Raran Fan, PinShuo Hwang, ChaoWei Liu, ChinYu Liu, MinHsiung Shih, YiJen Chiu, AnnKuo Chu, ChaoKuei Lee Supercontinuum generation(SCG) has been attracting plenty of attention due to its wide application, such as OCT and communication. In this work, anomalous dispersion Ta2O5 based waveguide was designed and fabricated for the supercontinuum generation(SCG) due to its nature of twophoton absorption free and high optical nonlinearity. The 5mm length air cladding Ta2O5 waveguide with a dimension of 800nm x 700nm was designed and fabricated for fulfilling anomalous dispersion requirement which is crucial for SCG. For excitation laser wavelength of 1056nm, with excitation peal power of around 400W, the 1.5 octavespanning was demonstrated. Compared to a SiNbased nonlinear waveguide, the resulting exhibit Ta2O5 based waveguide a promising material for SCG. 

G70.00269: GENERAL THEORY AND COMPUTATIONAL PHYSICS


G70.00270: Theoretical Prediction of Sulfides Under Pressure Nisha Geng Inspired by the discovery of high temperature superconductivity in the hydrogen/sulfur system, the XtalOpt evolutionary algorithm has been used to predict the structures of binary and ternary sulfides under pressure. A number of stable and metastable phases with novel stoichiometries are found at pressures attainable in diamond anvil cells. The electronic structure and superconducting properties of these phases are analyzed. 

G70.00271: Firstprinciples calculation of thirdorder elastic constants via numerical differentiation of the second PiolaKirchhoff stress tensor David Cuffari, Angelo Bongiorno Thirdorder elastic constants (TOECs) of materials are difficult to measure experimentally and produce large errors. Computational methods are needed for overcoming these difficulties. Previous methods to calculate TOECs are based on fitting energystrain and/or stressstrain curves calculated from density functional theory (DFT). These methods rely on symmetry relationships, and for this reason, so far they have been applied mainly to cubic and hexagonal crystals. In this paper, we present a novel method to calculate TOECs that is applicable to any system, regardless of its symmetry and dimensionality. This method relies on secondorder numerical differentiation of the second PiolaKirchhoff stress tensor. In this work, we combine this method to a planewave DFT approach to calculate the TOECs of aluminum, diamond, silicon, magnesium, graphene, and graphane. A comparison to experimental results shows that our new method is valid and accurate. 

G70.00272: Development of Multiphase EOS Table for Gallium Carrie Prisbrey, Christine J Wu We present a multiphase equation of state (EOS) table created at Lawrence Livermore National Laboratory for Gallium (Ga). Gallium is an interesting material as it has a low melting temperature of only a few degrees above room temperature, and the GaI solid, found at room temperature and pressure, exhibits the properties of both covalent and metallic bonding. Gallium is unusual in that its liquid phase is more dense than the GaI solid, leading to a melt line of negative slope. Our EOS captures the anomalous behavior of the liquid phase as well as the three commonly known solid phases, GaI, GaII, and GaIII. The table is constrained by published experimental data such as DAC, isobars, and Hugoniot measurements. In addition, we plan to test our EOS against the newest dynamic measurements taken at the Z facility at Sandia National Laboratory. 

G70.00273: Mechanisms of optically initiated decomposition of MgOPETN and MgOTNT composites Roman Tsyshevskiy, Anton S. Zverev, Anatoly Y. Mitrofanov, Maija M Kukla Optical initiation to detonation of energetic materials (EMs) opens up new ways for safe handling, storage, and use of high explosives. EMoxide interfaces have distinct optical and electronic properties because of the alignment of the filled and vacant electronic states of oxides and EMs. These changes are key factor for achieving tunable sensitivity through controllable initiation of decomposition reactions. We report here results of experimental and theoretical study on photointiation of PETNMgO and TNTMgO composites. We discuss electronic and optical properties of these materials and reveal mechanisms of photoinitiation reactions involving charge transfer from metal oxide to explosive compound. We also show how chemical stability of ionized explosive compounds can be critical for design composite materials with controllable optical sensitivity. 

G70.00274: Orientation dependence of plasticity and transformation kinetics in Zirconium at higher shock pressure Hongxiang Zong, Turab Lookman, Andreas Hermann, Graeme Ackland We simulated the high pressure phase transformation in zirconium using molecular dynamics with a new EAM potential fitted using force matching. Under quasistatic ("Hugoniostat") conditions the transformation from αω follows the phase diagram, as expected. However under directly simulated shock conditions the structure transforms from αβ (hcpbcc) rather than the expected ω phase. Assuming sudden, isotropic pressurization we trace this to a different phase transformation mechanism (socalled TAO1) in which bcc appears as an intermediate state, and under pressure the barrier hcpbcc is lower than bccω. The assumption of isotropic loading requires significant plasticity, which we also simulated and found to be of marginal validity. Plasticity depends on the crystal orientation and in the absence of ideal plasticity, so does the transformation path and, indeed, the observed high pressure phase. We have determined the orientational dependence of the transformation kinetics between hcpωbcc and hcpbcc at higher shock pressure. 

G70.00275: ElectronPhonon Coupling in AgAu Alloys Surender Singh, Dasari Prasad Superconductivity at ambient temperature and pressure has been recently inferred from the data of electrical resistance and magnetic susceptibility measurements on AgAu alloy nanostructures [1]. In view of this, electronphonon interactions have been calculated by means of density functional perturbation theory to search for the signatures of superconductivity in stable and metastable AgAu bulk and nanostructured alloys within the BCSlike pairing mechanism. The electronic structure and phonons of the alloys are found to be similar to that of the constituent elements in their ground states. And, therefore, the estimated superconducting transition temperatures resulted in less than a mK. Our computational results corroborate with the findings of absence of superconductivity in Ag/Au modulated nanostructures grown by pulsed laser deposition [2]. The results will be discussed in detail in two parts: alloy structure solutions and electronphonon – superconductivity. 

G70.00276: Thermal transport theory of organic semiconductors Nianduan Lu, Jiawei Wang, Ling Li, Ming Liu Organic semiconductors (OCSs) have very recently received much attentions as potential thermoelectric materials, originating from the fact that they are both semiconducting and that they exhibit relatively low thermal conductivity than that of inorganic materials. The low thermal conductivity of OCSs can remarkably increase the energy conversion efficiency. Generally, thermal transport in OCSs fundamentally differs from that in inorganic materials and is determined by the charge carriers and phonons in localized states. Understanding thermal transport performance of OCSs is important for a fundamental description of energy flow and then a better design of organic thermoelectric devices. We present a unified theoretical model to describe the thermal transport performance of the OCSs based on hopping transport theory. The proposed model predicts that the contribution from phonon to the thermal conductivity is larger than that from charge carrier in the OCSs. Moreover, the proposed model can well interpret the thermal transport feature of the OCSs by combining the disorder, temperature, and carrier concentration. Simulation results imply that thermal conductivity in the OCSs could be strongly affected under large electric field, high carrier and dopant concentration. 

G70.00277: Dimensionalityinduced phonon softening: effect on electronphonon coupling and transport Sushant Kumar, Ravishankar Sundararaman Classical elasticity theory predicts that finitethickness unstrained materials should exhibit a quadratic flexural phonon mode. However, stateoftheart computational methods have been largely inconsistent in yielding such a behavior for the phonon dispersion curves of twodimensional (2D) materials and their heterostructures. Given the enormous attention 2D materials have received in recent decades, it is imperative to understand the impact of this phonon softening on ab initio predicted electronphonon coupling strength and resultant transport properties. Recently, a new formulation of phonon calculations based on internal rather than Cartesian coordinates has observed that capturing rotational invariance in addition to translation invariance captures the quadratic mode correctly. Here, we investigate the role of rotational invariance on predicted phonon dispersion curves rigorously, and systematically quantify its impact on electronphonon scattering rates. We show that the crossover from a linear to quadratic dispersion of the transverse acoustic branch strongly affects transport properties such as electrical and thermal conductivity when we move from bulk to few and singlelayer materials. 

G70.00278: Laplace transform approach for the dynamics of N qubits coupled to a resonator Mirko Amico, Oleg Berman, Roman Kezerashvili An approach to use the method of Laplace transform for the perturbative solution of the Schrodinger equation at any order of the perturbation for a system of N qubits coupled to a cavity with n photons is suggested. We investigate the dynamics of a system of N superconducting qubits coupled to a common resonator with timedependent coupling. To account for the contribution of the dynamical Lamb effect to the probability of excitation of the qubit, we consider counterrotating terms in the qubitphoton interaction Hamiltonian. As an example, we illustrate the method for the case of two qubits coupled to a common cavity. The perturbative solutions for the probability of excitation of the qubit show excellent agreement with the numerical calculations. 

G70.00279: SizeControlled Carrier Multiplication in Graphene Nanoribbons Junhyeok Bang Carrier multiplication (CM) is a fundamental dynamic process of an excited carrier generating multielectronhole pairs from singlephoton absorption. As such, CM can improve the efficiency of optoelectronic devices. However, CM is rarely witnessed in conventional semiconductors, calling for the need to discover unconventional materials. Here, using realtime timedependent density functional theory, we show that CM occurs in armchair graphene nanoribbons (AGNRs). The subband structure of AGNRs plays a key role, as it releases the constraints of energy and momentum conservation in the CM process. The subband structure varies depending on nanoribbon width, and thus it provides the way to control the carrier dynamics and carrier multiplication in AGNRs. 

G70.00280: Firstprinciples photoelectron spectroscopy in molecular solids from multiscale GWBSE/MM embedding Gianluca Tirimbó, Xander de Vries, Peter Bobbert, Reinder Coehoorn, Björn Baumeier Charge/exciton transport properties of organic semiconductors make these materials attractive for use in optoelectronic devices. Understanding how inter and intramolecular interactions affect, e.g., transport energy levels is vital for engineering new materials and devices. Computational studies aiming at quantitative predictions must reflect the interplay of molecular electronic structure and local and mesoscale environment in realistic experimental and working conditions. 

G70.00281: Firstprinciples ultrafast charge carrier dynamics at the hybrid F4TCNQ:HSi(111) interface Matheus Jacobs, Jannis Krumland, Ana Maria Valencia, Caterina Cocchi Hybrid inorganicorganic materials are typically characterized by chargetransfer excitations across their interface that make them appealing candidates for optoelectronic applications [1]. However, the fundamental processes leading to the formation and the evolution of these states are still under debate. To address this question, we investigate from first principles the hybrid interface formed by the strong acceptor F4TCNQ adsorbed on the Si(111) surface, which is pdoped in the ground state. Its linearabsorption spectrum exhibits two maxima in the visible region corresponding to transitions between the electronic states across the inorganic and components. We investigate the dynamics of these excitations triggered by resonant ultrafast laser pulses, following the evolution of the chargecarrier population. To do so, we adopt the formalism of realtime timedependent densityfunctional theory as implemented in the octopus code [2]. Our results offer insights into the earlieststage formation of the optical excitations in hybrid interfaces. 

G70.00282: Adsorption of molecular oxygen on Tidoped monolayer MoS_{2} and effect of applied electric field: A DFT study Xiangxuan Deng It is proposed that by tuning the O_{2} adsorption on Tidoped MoS_{2}, the resulting materials system can be used as nanocatalyst. To this end, density functional theory calculations was first performed to study the adsorption of molecular oxygen on pristine MoS_{2} and Tidoped MoS_{2}. It was found that O_{2} molecule adsorption energy on pristine MoS_{2} was very weak. However, the adsorption of O_{2} molecule on monolayer Tidoped MoS_{2} shows relatively higher affinity. The results showed that the TibridgeO_{2} configuration is most stable. The analysis of molecular projected density of state and charge transfer indicates that the interaction between the O_{2} molecule and the Ti dopant is chemisorption via two TiO bonds, which affects the magnetic, electronic, and atomic properties of Tidoped MoS_{2}. Furthermore, the adsorption energy and OO distance of Tidoped MoS_{2} under electric field have been studied. It is hoped that together with electric field, the tuned O_{2} adsorption on Tidoped MoS_{2} could become a nanocatalyst. 

G70.00283: First principles theory of ground and excited states of correlated lightmatter systems in the nonperturbative regime Nicholas Rivera, Johannes Flick, Prineha Narang Ultrastrong coupling between light and matter promises to bring about new means to control material properties, concepts for manipulating light at the atomic scale, and insights into quantum electrodynamics (QED). Thus, there is a need to develop quantitative theories of QED phenomena in complex electronic and photonic systems. Here, we develop a new variational paradigm to analyze ultrastrongly coupled lightmatter systems which gives ground and excited state information as well as realspace information about electromagnetic fields as they are modified by strong lightmatter coupling. Our method gives highly accurate energies for both ground and excited states for systems with many emitter levels and many photon modes that go beyond solvable model systems in quantum optics. One important result is that we arrive at the first theory of Lamb shifts and CasimirPolder forces in the ultrastrong coupling regime, which reveals new saturation effects that strongly suppress energy shifts as lightmatter coupling grows. Beyond accurate calculation of ground and excited state energies, our results will give accurate descriptions of lightemission phenomena in the nonperturbative regime. 

G70.00284: Solvent effect on charge transfer properties of the dyads of Sc_{3}NC_{80 }fullerenes using DFT Surya Timilsina Endohedral fullerenes are unique due to their ability to change their characteristics through the selection of endohedral body. The polarization energies and electric dipole moments of the ground state endohedral Triscandium Nitride C80 fullerene (Sc3NC80) and two of its dyads viz. Sc3NC80 _Pc and Sc3NC80_ZnPc have been analyzed using density functional theory in all electron level in a solvent medium. For this, three polar solvents water, aniline, and toluene having static permittivity 78.39, 6.89 and 2.379 respectively are used. The calculation indicates that there is a linear correlation between electrostatic polarization energy and dipole moments of Sc3NC80 and Sc3NC80_ZnPc with the dielectric permittivity of the solvents. However, the trend for Sc3NC80_Pc is deviated slightly, which is scrutinized in DFT level by considering cationic and anionic clusters to study solvent effect. A comparison of results is made with earlier studies of Sc3NC80 systems using DFT in a gas phase, which established small charge transfer from the external complex to the fullerene, takes place even more rigorously in solvent perturbed Sc3NC80 systems. This study, in future, can be applied in the development of the efficient photovoltaic cell. 

G70.00285: Exciton Characteristics in Carbon Nitride and Graphene Quantum Dots Naeem Ullah, Shunwei Chen, Ruiqin Zhang Graphene quantum dots (GQDs) and Carbon nitride quantum dots (CNQDs), the latest addition to the carbon material family, promise numerous novel applications in optical sensing, photocatalysis, biosensing, and photovoltaics. However, understanding the photocatalytic capability of CNQDs compared to the graphene quantum dots (GQDs) have not been investigated thoroughly. Timedependent density functional tight binding (TDDFTB) calculations in this work revealed that CNQDs have superior carrier charge separation, sensitive to the size of the QD. Strong localization of the frontier molecular orbitals (FMOs and excited state charge separation was observed in the first excited state due to the relaxation of the structure. The exciton structure reveals spatial confinement to the stretched CN bonds independent of the size of the QDs while there is no such exciton structure found for GQDs. The optical absorption and emission of CNQDs is sensitive to size, with no dependence on the shape of the QD. 

G70.00286: Electrical Contacts in Monolayer Blue Phosphorene Devices Jingzhen Li Semiconducting monolayer (ML) blue phosphorene (BlueP) shares similar stability with ML black phosphorene (BP) and has recently been grown on the Au surface. Potential ML BlueP devices often need a direct contact with metal to inject carrier. Using ab initio electronic structure calculations and quantum transport simulations, we perform a systematic study of the interfacial properties of ML BlueP in contact with metals spanning a wide work function range in a field effect transistor (FET) configuration for the first time.There is a strong Fermi level pinning (FLP) in the ML BlueP FETs due to the metal induced gap states (MIGS). The MIGS are eliminated by inserting graphene between ML BlueP and the metal electrode accompanied by a transition from a strong FLP to a weak FLP. Our study not only provides an insight into the ML BluePmetal interfaces but also helps to design the ML BlueP device. 

G70.00287: Deep Bandgap and Band Structure Engineering by Machine Learning Zhe Shi, Evgenii Tsymbalov, Ming Dao, Subra Suresh, Alexander Shapeev, Ju Li The ability to deform and keep silicon at large strains harbingers a new age of deep elastic strain engineering (ESE) of electronic materials. Current strainedSi technology thus represents only “tip of the iceberg” of what silicon can do as the most versatile and processable electronic material. Deep ESE explores the full sixdimensional space of admissible elastic strain and its effect on physical properties, beyond linear elasticity and perturbation theory. Here we present a general method that combines machine learning and ab initio calculations to guide rational ESE whereby unprecedented material properties and performance could be designed. This method invokes recent advances in artificial intelligence by utilizing a limited amount of ab initio data for the training of a surrogate model. In particular, an artificial neural network predicts the electronic bandstructure within the accuracy of 19 meV. Our model is utilized to discover the indirecttodirect bandgap transition and semiconductortometal transition in the entire strain space. By finding out the most energy efficient deformation manner to achieve a desirable bandgap, we demonstrate for the first time how to identify novel pathways to tailor any material figure of merit, which is of central importance for ESE. 

G70.00288: Machine learning predictions of nuclear stability Roberto Pérez, Alexander Balatsky Machine learning (ML) methods have become a useful tool in many areas of physics, including Nuclear Physics. ML methods' ability to take in aggregate information about the behaviour of the system and predict trends is able to make relevant and verifiable predictions. The existence of super heavy stable nuclei in currently experimentally inaccessible regions has been predicted by the nuclear shell effect, however, its location and extension are still in dispute by different models (e.g. Z=120 N=172 from relativistic models) [1]. We aim to apply ML tools to develop accurate statistical models to predict isotopic lifetimes in regions of heavy nuclei, such as the fabled stability island. We explore various ML methods, and study the predictive power of different nuclear representations. We use ML models both with and without theoretical bias from nuclear models, such as isotopic magic numbers, over different radioactive decay channels to possibly offer a glimpse of the next stability region. 

G70.00289: Lowenergy physics of the bilinearbiquadratic spin1 chain Moritz Binder, Thomas Barthel The bilinearbiquadratic spin1 chain features various interesting quantum phases, including the Haldane phase, a dimerized phase, and an extended critical phase. Here, we apply an efficient density matrix renormalization group (DMRG) algorithm utilizing infinite boundary conditions to compute precise dynamic spin structure factors for a comprehensive set of points in the phase diagram. Analyzing both dynamic spin and quadrupolar correlations, we gain detailed insights into the nature of lowlying excitations of the model. We compare our results to Bethe ansatz solutions at the SU(3)symmetric ULS point and the TB point as well as at the pure biquadratic point, which can be mapped to an anisotropic spin1/2 XXZ chain in the gapped Néel phase. In the Haldane phase, we relate our results to the approximate description in terms of the nonlinear sigma model. 

G70.00290: Spincharge cooperation in evenparity three dimensional nodal superconductivity in strained Sr_{2}RuO_{4} Swagata Acharya, Cedric Weber, Mark Schilfgaarde We develop a threetier ab initio technique to study the origin and nature of the pairing in Sr_{2}RuO_{4}. The technique starts with the quasiparticle self consistent GW (QSGW) approximation to build a reference hamiltonian, augment it with dynamical mean field theory (DMFT) to add spin fluctuations left out of QSGW, and also generate the vertices entering into spin, charge, and pairing susceptibilities. Finally we solve multiorbital BetheSalpeter equations to calculate these properties in both strained and unstrained single crystals. We identify what leads to the recently observed dependence of T_{c} on strain and also gain insights into what limits it. We find a onetoone correspondence between T_{c} and the coherence and intensity of the spin susceptibility under application of strain. Finally, we establish connections between spin fluctuations and superconducting pairing symmetries in Sr_{2}RuO_{4}, and dimensionality of the fluctuations associated with these degrees of freedom. 

G70.00291: Optimized higherorder LieTrotterSuzuki decompositions for two and more terms Yikang Zhang, Thomas Barthel LieTrotterSuzuki decompositions of operator exponentials have a lot of applications in physics. For example, they are employed to sample equilibrium states in quantum Monte Carlo and to simulate the dynamics of quantum systems on quantum computers or on classical computers using tensor network state techniques. They also provide symplectic integrators for classical physics. 

G70.00292: ParaMonte: A userfriendly parallel Monte Carlo optimization, sampling, and integration library for scientific inference Amir Shahmoradi At the foundation of predictive science lies the scientific methodology, which involves multiple steps of observational data collection, developing testable hypotheses, and making predictions. Once a scientific theory is developed, it can be cast into a mathematical model whose parameters have to be fit via observational data. This leads to the formulation of a mathematical objective function for the problem at hand, which has to be then optimized to find the bestfit parameters of the model, or sampled to quantify the uncertainties associated with the parameters, or integrated to assess the performance of the model. 

G70.00293: Numeric Analytic Continuation via Rational Function Regression (Padé Regression) Jian Wang, Sudip Chakravarty We have developed a simple and natural method to perform numeric analytic conitnuation of quantum Monte Carlo data. 

G70.00294: Beam Size Prediction and Control using Neural Network Shuai Liu, Charles Melton, Hiroshi Nishimura, Alexander Hexemer, Simon C Leemann Experimental results from beam lines are sensitive to the size of the beam itself. However, predicting and controlling the beam size still prove to be a challenge. Even with the feedforward strategy using recorded control data (aka lookup tables), the beam size variance on vertical direction is still ~2 μm. Herein, we provide a machine learning based approach to predict the beam size using neural network. We perform a systematic study to optimize the prediction result using different neural network architectures and regularizers. Based on the model, we propose a neural network based beam size stablization strategy by tuning a certain experimental parameter (dispersion wave parameter). The variance of beam size on vertical direction is reduced to ~0.3 μm in the online test. 

G70.00295: Conservation law presumption from the manifold structure captured by Deep Neural Networks Yohichi Mototake It is suggested that Deep Neural Networks (DNN), which continues to develop in recent years, has a function to extract information of data sets necessary to achieve a given task by modeling the distribution as a manifold. 

G70.00296: Effect of Different Types of Sulfur Precursors on Chemical Vapor Deposition Synthesis of MoS_{2} layers: A Reactive Molecular Dynamics Study Sungwook Hong, Ruru Ma, Kenichi Nomura, Rajiv Kalia, Aiichiro Nakano, Priya Vashishta Layered transition metal dichalcogenides (TMDCs) like MoS_{2} layers are promising materials for nextgeneration electronic applications. Largearea monolayer MoS_{2} samples for these applications are typically synthesized by chemical vapor deposition (CVD) using MoO_{3} reactants and sulfur precursors. Recent experimental and computational studies have greatly improved our understanding of reaction pathways in CVD synthesis. However, effect of different types of sulfur precursor on CVD synthesis of MoS_{2} layer has yet to be fully investigated. In this work, we present quantummechanically informed and validated reactive molecular dynamics (RMD) simulations to investigate CVD synthesis of MoS_{2} layer using S_{2} and H_{2}S molecules. Our goal is to clarify the different sulfidation and reduction rates of MoO_{3} surface by S_{2} and H_{2}S precursors. Our RMD results provide an atomic scale understanding of the CVD reactions for higherquality MoS_{2} and other TMDCs. 

G70.00297: Fracture in αQuartz under weak shock condition Subodh Tiwari, Masaaki Misawa, Tomoko Sato, Fuyuki Shimojo, Aiichiro Nakano, Toshimori Sekine, Paulo S Branicio, Priya Vashishta Shock response of α Quartz has been extensively studied using both experiment and theory. Here we present a large scale molecular dynamics simulations to study the atomistic mechanism underlying the weak shock response of  Quartz. First, classical potential (BKS) employed is verified against Density functional theory (DFT). We computed the shock hugoniot curve using BKS potential which show a quantitatively agreement with DFT. Further, we perform non adiabatic molecular dynamics for plane shock loading in [210] direction. Shock simulation reveals the formation of 5 coordinated Si atom in the banded region. 5 coordinated Si relax to form an banded amorphous region in the system. System between these banded amorphous region shows an elastic compression. Further, The generation of shockinduced plastic deformation is characterized using machine learning methods. 

G70.00298: Multiobjective forcefield parameterization for thermal transport in 2D materials Nicholas Grabar, Ankit Mishra, Aravind Krishnamoorthy, Aiichiro Nakano, Rajiv Kalia, Priya Vashishta Forcefields for the calculation of thermal properties of nanomaterials must be parameterized to match empirical material properties. Here, the third generation of the NonDominated Sorting Genetic Algorithm (NSGAIII) is used to construct forcefields to model 2D semiconducting materials by optimizing structure parameters (lattice constants), mechanical properties (elastic modulus) and vibrational behavior (phonon dispersion curve) from ab initio simulations. The algorithm is a parallelized, crossplatform workflow, written in C, that uses GULP as the engine for validating constructed forcefields. NSGAIII is a referencepointbased manyobjective algorithm emphasizing population members that are nondominated, yet close to a set of supplied reference points. It can handle up to fifteen variables and reference point tuning allows for user tuned diversity in the end product. This will allow for future expansion into forcefields finelytuned over additional variables. 

G70.00299: Learning StructureThermal Property Relationships in 2D Materials Nitish Baradwaj, Aravind Krishnamoorthy, Aiichiro Nakano, Rajiv Kalia, Priya Vashishta Two dimensional monolayer semiconductors, alloys and patterned lateral heterostructures are extremely promising candidates for the next generation of nanoelectronic devices. Quantification of thermal transport of such two dimensional materials and heterostructures is necessary for the design of such nanoelectronic and thermoelectric devices. However, direct experimental measurements of intrinsic thermal conductivity is challenging at these length scales and, therefore, the role of material stoichiometry and phase distribution on thermal transport properties of these materials remains unknown. 

G70.00300: Global warming impact on low frequency acoustic propagation in Pacific Ocean equatorial surface ducts: a potential paradox. David Browning A typical Pacific Ocean pH profile has a value of 8.1 at the surface decreasing to 7.7 at the axis of the SOFAR channel (400m). Absorption in seawater of low frequency sound is pH dependent, so that the low frequencies that are contained in a surface duct will be absorbed at twice the rate of those in the SOFAR channel. Global warming is producing ocean acidification which is reducing the pH, hence the low frequency sound absorption, and this will first impact the surface duct. But global warming is also predicted to increase the rainfall and as these equatorial surface ducts are produced from monsoon conditions, the suface duct would be deepened and thus expand the low frequencies contained in it, which would now be absorped at a higher rate than in the SOFAR channel. This is just a first look into one aspect of what may prove to be a multifaceted and complex interaction of global warming on acoustic propagation conditions in the ocean. 
(Author Not Attending)

G70.00301: Aimsgb: An algorithm and opensource python library to generate periodic grain boundary structures Kesong Yang, Jianli Cheng An algorithm implemented in an opensource python library was developed for building periodic grain boundary models in a universal fashion. The software framework, aimsgb, aims to generate tilt and twist grain boundaries from an input cubic or noncubic crystal structure for abinitio and classical atomistic simulation. It can output a coincidence site lattice (CSL) grain boundary for a cubic input structure and a nonCSL grain boundary for a noncubic input structure. This framework has two useful features: (i) it can calculate all the CSL matrices for generating CSL from a given Sigma (Σ) value and rotation axis, allowing the users to build the specific CSL and grain boundary models; (ii) it provides a convenient command line tool to enable highthroughput generation of tilt and twist grain boundaries by assigning an input crystal structure, Σ value, rotation axis, and grain boundary plane. The developed algorithm in the opensource python library is expected to facilitate studies of grain boundary in materials science. The software framework is available on the website: aimsgb.org. 
(Author Not Attending)

G70.00302: Electrochemical Stability Window of Polymeric Electrolytes Lihua Chen, Shruti Venkatram, Chiho Kim, Anand Chandrasekaran, Ramamurthy Ramprasad The electrochemical stability window (ESW) is a fundamental consideration while choosing polymers for electrolytes in lithiumion batteries. In this work, we propose two computational procedures, viz. firstprinciples density functional theory (DFT) computations coupled with classical molecular dynamics (MD) simulations and machine learning (ML) methods to efficiently and accurately estimate ESW of polymers electrolytes. Six model polymers were investigated, namely, polyethylene (PE), polyethylene oxide (PEO), polyvinyl alcohol (PVA), poly(methyl methacrylate) (PMMA), polycaprolactone (PCL) and polyvinyl chloride (PVC). The role of polymer chemistry and the morphological complexity in determining ESW of these polymers have been elucidated. Comparison with established experimental values revealed that the ESW can be accurately predicted using DFT calculations coupled with MD simulations. However, this method is still timeconsuming and the relevant force fields are limited, therefore ML methods are proposed to predict the ESW of single chain models with a firstorder accuracy instantaneously. Overall, these two computational procedures proposed in this work can assist the rational design of novel solid polymer electrolytes with desired ESW values. 

G70.00303: Coevolutionary search for CuPdAg nanoparticle ground states accelerated with neural network potentials Aiden Cullo, Samad Hajinazar, Ernesto D. Sandoval, Aleksey Kolmogorov Unconstrained optimization of nanoparticles requires advanced search methods capable of locating global minima in large configuration spaces. In this study, we demonstrate that algorithm efficiency can be improved substantially if ground state searches are performed across a range of nanoparticle sizes simultaneously. In this symbiotic coevolutionary approach implemented in our MAISE package [1], stable motifs are periodically exchanged among tribes with neighboring nanoparticle sizes. The algorithm was extensively tested on elemental Cu, Pd, and Ag nanoparticles up to 80 atoms using both traditional classical potentials and our neural network models. Examination of the lowestenergy configurations revealed that the neural network set was consistently more stable at the density functional theory level. Lastly, we used our CuPdAg neural network model to identify stability regions in binary and ternary systems. 

G70.00304: Are Small Polarons Always Detrimental to Transparent Conducting Oxides ? Guillaume Brunin, GianMarco Rignanese, Geoffroy Hautier Transparent conducting oxides (TCOs) are critical components in many devices like solar cells or touchscreens. The search and development of new TCOs combining high conductivity and transparency is a major endeavor of modern Materials Science. Novel ptype TCOs are especially greatly sought for as they lie much behind their ntype counterpart and the discovery of a high performance ptype TCO would enable important technological breakthroughs. 

G70.00305: Point charged defects in 2D and 3D hBN: A density functional theory study Pradip Niraula, Angelo Bongiorno In this work, we first calibrated a density functional theory (DFT) approach, and then I carried out DFT calculations to study the properties of charged point defects in monolayer, bilayer, and bulk hBN. In particular, we considered a DFT approach using a semiempirical scheme to account for Van der Waals forces, and we optimized the dispersive coefficient of B to obtain a description of the structural and mechanical properties of bulk hBN in agreement with the experiments. The resulting optimized DFT scheme was used to calculate formation energies and electronic properties of neutral and charged B and N vacancies, as well as C substitutional defects for both N and B sites. To correct the formation energies of charged defects, we used a novel polarizable force field. Our calculations show that, due to electrostatic polarization, the formation energy of charged defects in bilayer hBN is about 0.5 eV lower than in monolayer hBN. Furthermore, we found that assuming that the aforementioned four types of point defects are present with a finite concentration in mono and bilayer hBN, there is always a class of defects that is likely to be charged, regardless of the position of the Fermi level. 

G70.00306: Is Defect Segregation Facile in the Grain Boundary of Methylammonium Lead Iodide? Xin He, Wissam Saidi, Lijun Zhang Methylammonium Lead Iodide (MAPbI_{3}) is emerging as one of the most promising materials for solar cells. Grain boundaries (GBs) and native point defects are ubiquitous in MAPbI_{3 }given that solutionbased methods generate polycrystalline materials. Our previous study has shown that there is a strong thermodynamic preference of iodine point defects to exist in the GB region rather than in the interior of the MAPbI_{3 }grain [Shan and Saidi, J. phys. Chem Lett. 8, 5935 (2017)]. This would generate defect segregation to the GB, provided that defect diffusion is not hindered at room temperature. In this talk, we examine the energy barriers and possible kinetic limitations of the diffusion of iodine interstitials and vacancies in Σ5 (210) MAPbI_{3 }GB, and contrast the results with their diffusion in crystalline system. 

G70.00307: Lonepair electrons induced anomalous enhancement of thermal transport in strained planar twodimensional materials Guangzhao Qin, Ming Hu Manipulating heat conduction is an appealing thermophysical problem with enormous practical implications, which requires insight into the lattice dynamics. Strain engineering is one of the most promising and effective routes towards continuously tuning the thermal transport properties due to the flexibility and robustness. However, previous studies mainly focused on quantifying how the thermal conductivity is affected by strain, while the fundamental understanding on the electronic origin has yet to be explored. In this talk, I would like to show that the thermal conductivity (κ) of planar monolayer group IIInitrides is unexpectedly enlarged by one order of magnitude with bilateral tensile strain applied, which is in sharp contrast to the strain induced κ reduction in graphene despite their similar planar honeycomb structure. The anomalous positive response of κ to tensile strain is attributed to the attenuated interaction between the lonepair s electrons around N atoms and the bonding electrons of neighboring (B/Al/Ga) atoms, which reduces phonon anharmonicity. The microscopic picture for the lonepair electrons driving phonon anharmonicity would have great impact on future research in materials design with targeted thermal transport properties. 

G70.00308: Surface plasmon polariton excitation in exfoliated MoS_{2} flakes on Au nanogratings Soyeong Kwon, Min Hee Kwon, Jungeun Song, Bo Ra Kim, Eunah Kim, Sang Wook Lee, Dongwook Kim We prepared MoS_{2} flakes on Au nanogratings to investigate how the surface plasmon polariton (SPP) excitation can affect physical properties of MoS_{2}. SPP – the propagating electromagnetic and charge wave at metal/dielectric interface – can be excited using grating structures by overcoming the momentum mismatch between the impinging photons and the SPPs. The MoS_{2} flakes were exfoliated from its bulk and transferred on the Au nanogratings (period: 500 nm) fabricated by electron beam lithography. The number of MoS_{2} layers was identified using microRaman and atomic force microscopy measurements. Finitedifference timedomain simulations showed clear signature of the SPP excitation in the electric field intensity distributions and optical reflection spectra of the Au nanogratings. The work function of the MoS_{2} flakes was measured using Kelvin probe force microscopy, and its variation in dark and light was studied to understand the interaction between the SPPs at the MoS_{2}/Au interface and charge carriers in the MoS_{2} flakes. This study can help us to develop new kinds of 2D transition metal dichalcogenide semiconductorbased plasmonic devices. 

G70.00309: Giant effect of spinlattice coupling on the thermal transport in twodimensional ferromagnetic CrI_{3} Guangzhao Qin, Ming Hu Recently, twodimensional monolayer chromium triiodide (CrI_{3}) with intrinsic magnetism was experimentally discovered, which shows promising applications in many technologies ranging from sensing to data storage where thermal transport plays a critical role. However, so far, the effect of spinlattice coupling on the thermal transport properties has not been explored yet. In this talk, I will present the giant effect of spinlattice coupling on the lattice thermal conductivity (κ_{L}) of monolayer CrI_{3}. The lattice thermal conductivity is more than two orders of magnitude enhanced by considering the spinlattice coupling. The effect is found to be especially stronger for the acoustic phonon modes, which dominates thermal transport with spinlattice coupling. The mechanism lies in the weakened phonon anharmonicity by spinlattice coupling. The bond angle and atomic position are changed due to the spinlattice coupling, making the structure much stiffer and more symmetric, which lead to the weaker phonon anharmonicity, and thus the enhanced thermal conductivity. This study uncovers the effect of spinlattice coupling on the thermal transport, which would deepen our understanding on thermal transport and shed light on future research of thermal transport in magnetic materials. 

G70.00310: Size and Substrate effect on excitation dynamics of 2D materials Subodh Tiwari, Hiroyuki Kumazoe, Shogo Fukushima, Aravind Krishnamoorthy, Fuyuki Shimojo, Rajiv Kalia, Aiichiro Nakano, Priya Vashishta Excitation dynamics of 2D materials has been extensively studied by different theoretical and experimental methods. However, effect of substrate and size effect on the excitation dynamics of 2D materials has not been well delineated due to large number of atoms. We perform quantum molecular dynamics simulations at high electron temperatures within the density functional theory framework to understand the effect of substrate and size. We computed the intralayer mean square displacement and Debyewaller factor of top and bottom layer of WSe_{2}._{ }The simulation results show that interaction between substrate and transition metal dichalcogenide layers create distinct anisotropy in electronic excitationinduced lattice dynamics that may be experimentally observable. 

G70.00311: Abinitio Study of Electronic Properties of Tidoped VO_{2} Nanowire Prabal Bhuyan, Sanjeev K. Gupta, Yogesh Sonvane, P. N. Gajjar Vanadium oxide (VO_{2}) nanowire undergoes a phase transition at 341K and shows metalinsulator transition (MIT). We have considered hightemperature VO_{2}NW structure, which is stable in rutile form. The state of art density functional calculation has shown metallic in VO_{2} (R) rutile structure nature. Further, we have investigated the doping effect of Ti substitution for V in VO_{2}NW. A transition of metallic to semiconducting behaviour is observed by the presence of Ti3d orbital and it is also confirmed by the partial density of states (PDOS) that contribution of Ti3d orbital near the Fermi level at conduction band. We have observed band gap of 1.83eV, however band gap decreases with the increase in Ti concentration. Furthermore, Tidoped VO_{2}NW shows adsorption energy at visible region, which attributes to its potential application in nanooptoelectronic devices. 

G70.00312: Lithium adsorption and diffusion on Janus Mo/WXY (X,Y = S, Se, Te) Gracie Chaney, Fatih Ersan, Can Ataca One of the most important factors in improving the efficiency of anode materials for Liion batteries is the mobility of Lithium atoms in these materials. On the basis of firstprinciples planewave calculations, we examined the adsorption and diffusion of lithium atoms on the hexagonal Janus Mo/WXY (X,Y=S, Se and Te) monolayers. We found the lowest energy adsorption positions of the Li adatom to be on the top site of the transition metal atom, on both sides of all considered Janus monolayers. Due to electronegativity differences of the chalcogenides in the Janus structures and induced dipole moment, both the Li adatom adsorption and the diffusion barrier energies on the surfaces of Janus structures differ from the bare Mo/WX2 monolayers. For instance, Li diffusion barrier energy for the Tellurium sides of the MoJanus structures are about 0.090.12 eV lower than that of MoTe2 monolayers which is 0.23 eV. Also, Li diffusion barrier energy on the Sulfur sides of the MoJanus monolayer is about 0.040.08 eV larger than its MoS2 energy value. All considered structures turn to metal after Li atom absorption. Our electronic transport calculations concluded inn an increase in conductivity. This makes them superb candidate materials for the electrodes of Liion batteries. 

G70.00313: WITHDRAWN ABSTRACT


G70.00314: Electronic structrure and optoelectronic properties of 4',5'dibromo2',7'dinitro3oxo3Hspiro[2benzofuran1,9'xanthene]3',6'diolate Jean Baptiste Fankam Fankam The molecular structure, electric parameters and optoelectronic properties of 4',5'dibromo2',7'dinitro3oxo3Hspiro[2benzofuran1,9'xanthene]3',6'diolate have been theoretically studied. We used the RHF and DFT (PBE1PBE, MPW1PW91, B3PW91 and B3LYP) approach to calculate the optimized parameters, molecular structure, electric parameters and optoelectronic properties of the tilted compound with ccpVDZ basis set. The larger the HOMOLUMO energy gap, the harder and more stable (less reactive) the compounds. The lowest value (3.78eV) is shown in B3LYP is most stable and the highest value (8.81eV) in RHF is least stable. The effect of correlation decreased the value of HOMOLUMO energy. Our results suggest that this molecule have potential applications as linear and nonlinear optical materials. Due to the large hyperpolarizability of this molecule, we think that these molecules have potential applications in thoptoelectronic and can be a promising material for optical limiting applications. 

G70.00315: Highaccuracy largescale DFT calculations using localized orbitals in complex electronic systems: The case of graphenemetal interfaces Carlos RomeroMuñiz, Ayako Nakata, Pablo Pou, David R Bowler, Tsuyoshi Miyazaki, Ruben Perez Over many years, computational simulations based on Density Functional Theory (DFT) have been used extensively to study many different materials at the atomic scale. However, its application is restricted by system size, leaving a number of interesting systems without a highaccuracy quantum description. In this work, we calculate the electronic and structural properties of a graphenemetal system significantly larger than in previous planewave calculations with the same accuracy. For this task we use a localized basis set with the Conquest code, both in their primitive, pseudoatomic orbital form, and using a recent multisite approach [1]. This multisite scheme allows us to maintain accuracy while saving computational time and memory requirements, even in our exemplar complex system of graphene grown on Rh(111) with and without intercalated atomic oxygen. This system offers a rich scenario that will serve as a benchmark, demonstrating that highly accurate simulations in cells with over 3000 atoms are feasible with modest computational resources. 

G70.00316: GTPack: A Mathematica group theory package for application in solidstate physics and photonics Richard Geilhufe, Wolfram Hergert We present the Mathematica group theory package GTPack providing about 200 additional modules to the standard Mathematica language. The content ranges from basic group theory and representation theory to more applied methods like crystal field theory, tightbinding and planewave approaches capable for symmetry based studies in the fields of solidstate physics and photonics. GTPack is freely available via http://gtpack.org. The package is designed to be easily accessible by providing a complete Mathematicastyle documentation, an optional input validation and an error strategy. We illustrate the basic framework of the package and show basic examples to present the functionality. 

G70.00317: Band structure theory of twisted bilayer graphene XingJu Zhao, DongBo Zhang Twisted bilayer graphene show various interlayer interaction under different rotation angles, which make the system presents nontrivial physical properties, such as unconventional quantum hall effect and berry's phase, correlated insulator behaviour and unconventional superconductivity in magic angle graphene superlattice, et al. However, when the rotation angle is small, the electronic structure, such as band, can't be simulated by the firstprinciples method. In this project, combine tightbinding method and firstprinciples simulation, we construct interlayer Hamiltonian matrix element and improve the effective continuum model in band structure theory. Based on this, we construct the wavefunction of each layer in superlattice and then build the Hamiltonian matrix, which further simplify the band structure theory model. Finally, we extend this model to other 2D bilayer systems. The success implementation of this project will construct a simple, cheap and general method for band structure simulation of twisted bilayer graphene, and provide a useful tool for the relative physical effects study of 2D bilayer materials. 

G70.00318: Is selfinteraction corrected density functional theory straying from the path toward the exact functional? Sebastian Schwalbe, Torsten Hahn, Jens Kortus, Kai Trepte, Koblar Alan Jackson As recently pointed out [1] higher rung functionals (e.g. MGGA or hybrids) may deliver a better description of the total energy but not necessarily a better description of the density for the calculated systems. We present an additional perspective to this discussion and present the performance of selfinteraction corrected densities for LDA, GGA and MGGA rungs of density functionals for an extended benchmark set considering atoms, molecules and stretched bond situations. 

G70.00319: Strong correlation effect on the Seebeck coefficient from Density Functional Theory Roberto D'Agosta, Kaike Yang, Enrico Perfetto, Gianluca Stefanucci, Stefan Kurth Density Functional Theory (DFT) has become the standard for transport calculations due to its simplicity and widespread implementations. It has been shown that the theory fails, especially when dealing with strongly correlated systems. The standard approximations associated with the theory are the culprit for most of these failures, but we should also realize that static DFT should not deal with transport probelms. In this talk, we will discuss how to build a DFT theory that is able to describe strongly correlated effects [1]. In particular, we will discuss the correction for the Seebeck coefficient in the Coulomb blockade regime in a quantum dot in linear response [2]. We will show how the theory can compare with experiments and outline future research lines to extend the methods beyond linear response. 

G70.00320: ABSTRACT WITHDRAWN


G70.00321: SelfInteraction Error free Magnetic Exchange Couplings: LSDA vs PBE vs SCAN. Rajendra Joshi, Koblar Alan Jackson, Juan Ernesto Peralta We analyze the effect of selfinteraction error removal from density functional theory on magnetic exchange couplings using FermiLowdin orbital selfinteraction correction (FLOSIC) methodology. We compare selfinteraction corrected LSDA, PBE, and SCAN exchange couplings to the respective uncorrected ones and to 

G70.00322: Crossover Behavior of Entanglement Entropy for Energy Eigenstates of 1d and 2d Fermionic Systems Qiang Miao, Thomas Barthel The entanglement entropy in ground states of typical condensed matter systems obeys the area law or a logarea law for critical systems. Subsystem entropies in random and thermal states obey a volume law. Here, we discuss the distribution of entanglement entropy in energy eigenstates of quasifree fermionic systems as a function of energy and subsystem size. Numerical results are obtained with a Monte Carlo approach. We characterize the crossover behavior from the area or logarea law in the vicinity of the ground state and for small subsystem size to the volume law at higher energy and larger subsystem size. The coefficients of the volume law scaling can be matched to entropy densities in equilibrium thermal ensembles. For critical 1d systems at low energies, the universal crossover function matches the prediction from 1+1d conformal field theory for systems at nonzero temperatures. For 2d systems, we find a similar crossover behavior. 

G70.00323: Large N Tensor and SYK Models Jaewon Kim, Igor R Klebanov The SYK model consists of Majorana fermions that interact randomly four at a time. A holographic dual may exist for this model, which makes it interesting in the study of quantum gravity. It has been found that the SYK model is similar to large N tensor models: in both models, only the melonic diagrams survive in the large N limit. In this paper, we explore the large N tensor model with O(N)^3 symmetry containing two flavours of Majorana fermions in the fundamental representation, the quartic Hamiltonian of which depends on a real parameter. We derive the kernels of the four point functions. With these, we calculate the scaling dimensions of several types of conformal primaries. We also find a duality relation between two Hamiltonians of different real parameters. This is not a perfect duality, because the normalization of energy scales with the transformation. Nevertheless, the ratios of the energies are the same, and the operator dimensions are preserved. Last, for real parameters > 1 or < 0 the scaling dimensions of one of the conformal primaries become complex, rendering the model unstable. 

G70.00324: Molecular dynamics simulation for colletive phenomena in collisionless plasmas Ryusuke Numata, Yutaro Ikehata Plasmas are constituted of many charged particles interacting via the long range Coulomb force, and exhibit various collective phenomena. To describe plasma dynamics, we usually utilize some theoretical models, such as fluid models, or kinetic models, depending on the scale we are focusing on. Those theories are developed by employing some coarsegraining assumptions. However, essentially, plasma dynamics can be understood by individual particle dynamics. Particle based simulations for macroscopic plasma dynamics are still computationally demanding, yet they become feasible (eg. [1]) thanks to the rapid growth of computation technology and simulation techniques. 

G70.00325: The von Neumann and Double Slit Paradoxes Lead to a New Schrödinger Wave Mathematics Jeffrey Boyd John von Neumann states a paradox. Why does measuring something disrupt the smooth Schrödinger wave, causing it to collapse for no mathematical reason? This paradox is embedded in the double slit experiment. When a dot appears on the target screen, how does that cause the Schrödinger wave to collapse everywhere else, faster than the speed of light? Von Neumann didn’t follow his mathematics to its logical conclusion. If wave function collapse irreversably changes reality, then the math is telling us that the timing and location of that event cannot be at the target screen. An event fitting that description happens only once: at the gun. A gunshot CAN change history. We propose a new mathematics of Schrödinger waves. Zero energy waves from the target screen pass backwards through the double slits and impinge on the gun prior to the gun firing. A particle randomly chooses one to follow backwards. The particle’s choice of wave is proportional to the amplitude squared of that wave at the gun, determined by the superposition of the two waves moving backwards through the two slits. Why follow a wave of zero energy? Because Schrödinger waves convey amplitudes determining the probability density of that path. 

G70.00326: Effect of Electronelectron Scattering on Linear Conductivity for Graphenelike Band Structure Fereshteh Memarian, Ben YuKuang Hu We study theoretically the effect of electronelectron scattering on the electrical conductivity of twodimensional materials with linear bands such as graphene, both with and without a perpendicular magnetic field. The Boltzmann transport equation was utilized, where phonon and impurity scattering are modeled using the relaxationtime approximation. In graphenelike materials with linear bands, for a constant relaxation time, the conductivity decreases as the temperature increases from absolute zero. Furthermore, in linear band materials, the electronelectron scattering also decreases the conductivity. This is in contrast to parabolic band materials, where the conductivity for a constant relaxation time does not depend on temperature or the electronelectron scattering rate. We also investigate the magnetoconductance for linear band materials in the absence and presence of electronelectron scattering. 

G70.00327: Efficient Calculation of Lattice Thermal Conductivity by Molecular Dynamics Simulation: Role of IsobaricIsothermal Relaxation and Potential Cutoff Distance Sangwoo Kwon, Won Bo Lee This work studied the GreenKubo approach of calculating thermal conductivity with molecular dynamics (MD) simulation. In MD lattice thermal conductivity calculation, zeropressure volume relaxation in the isobaricisothermal (NPT) ensemble which determines lattice parameters, is often not included in standard procedure. Several MD simulations of fccbased structures with different lattice parameters were performed to calculate lattice thermal conductivity and phonon density of states. The results were compared to experimental references and ab initio datas to suggest that NPT relaxation is crucial for accurate thermal conductivity calculation. Moreover, dependency between potential cutoff and lattice thermal conductivity in MD simulation was also studied. The results suggested that lattice thermal conductivity is not strictly dependent on potential cutoff distance, but exactly function of lattice parameters given by NPT relaxation. We concluded that properly reducing the cutoff distance can greatly improve computation cost of thermal conductivity calculation without sacrificing the accuracy. 

G70.00328: Electronic Band Structure of ZnO, CdO, MgO and related alloys Nick Boecker, Mack Adrian Dela Cruz, Gary Pennington The electronic band structure of rocksalt CdO, ZnO, MgO and their ternary alloys are investigated using the empirical pseudopotential method and the virtual crystal approximation. This method is computationally efficient and highly advantageous when the band structure is needed on a very fine kspace mesh. A nonlocal pseudopotential correction with l = 2 symmetry is included for CdO and ZnO to account for the interaction between d and p electrons known in these materials. Additionally, an alloy compositional disorder potential term is included. Results are shown to agree well with known experimental band gap and band spacing energies. The cross over between direct and indirect minimum band gaps along with the conduction and valence band effective masses is studied for CdO, ZnO, MgO and their ternary alloys. Results have potential applications in optoelectronic devices. 

G70.00329: Nonequilibrium Electric Currentinduced Phonon Distribution in Microscale Metallic Structures Guanxiong Chen, Sergei Urazhdin The downscaling of modern electronic circuits places an increasing demand on the efficiency of heat dissipation. Electric currentinduced heating is generally described in terms of Joule heating – an increase of phonon temperature due to the scattering of electrons on impurities and phonons. We experimentally demonstrate that this interpretation is not universally applicable to microscopic metallic structures. We study the currentdependent resistance R(I) in Pt nanowires. For a 7 μmlong nanowire, we observe a parabolic dependence R(I) at all temperatures T=5 K – 295 K, consistent with the Joule heating. A 1 μmlong nanowire exhibits a similar dependence at T=295 K. In contrast, we observe a singular piecewiselinear dependence at 5 K. As consequence, currentinduced resistance increase is much larger than expected from Joule heating at small I, but smaller at large I. The linear dependence persists at modestly increased temperatures, but the singularity becomes broadened, reminiscent of common spectroscopic effects. Our observations are consistent with the nonthermal phonon distribution produced by electron scattering on impurities. The demonstrated effects provide an approach to characterizing and controlling thermal energy dissipation mechanisms. 

G70.00330: Optical manipulation of 40THz coherent phonons in diamond Yasuaki Okano, Hiroya Sasaki, Riho Tanaka, Kazuma Ohya, Hiroshi Takahashi, Tetsuya Tsuruta, Shinichi Uozumi, Katsura Norimatsu, Masahiro Kitajima, Fujio Minami, Yosuke Kayanuma, Yutaka Shikano, Kazutaka G Nakamura Coherent optical phonons in bulk solid system play a crucial role in understanding and designing lightmatter interactions. In this study, we demonstrated coherent control of the 40THz optical phonons in a single crystal diamond using a pair of sub10fs laser pulses and a pump and probe protocol. We detected the coherent phonon oscillation via change in transmitted light intensity of the probe pulse with heterodyne detection. The phonon amplitude was coherently controlled by changing the delay between two pump pulses from 230 fs to 270 fs with 0.5fs precession. The control scheme was well explained by interference between two phonon states excited by each pump pulse. 

G70.00331: Nonequilibrium Landauer approach for thermal interfaces Jingjing Shi, Xiaolong Yang, Timothy Fisher, Xiulin Ruan Thermal boundary conductance (TBC) is critical in thermal management of modern electronic devices, and the Landauer approach is the most widely method for predicting TBC due to its intuitive and transparent physics. However, a decadesold puzzle has been that many of the measured TBCs, such as those well characterized across Al/Si and ZnO/GaN interfaces, significantly exceed the Landauer approach prediction, or even its upper limit called the ”radiation limit”. Here, we identify that a key assumption used in the Landauer approach, that phonons are in thermal equilibrium at the interface, is generally invalid and contributes to the discrepancy. We show that the measurable 

G70.00332: Ionization energies and excited state lifetime of charged defects in Twodimensional Materials Yuan Ping, Tyler Smart, Marco Govoni, Feng Wu Defects in 2D materials such as ultrathin hBN have been found to be promising candidates for singlephoton emitters and quantum bits. However, firstprinciples prediction of accurate defect properties in 2D materials remains challenging, mainly because of the highly anisotropic 

G70.00333: Abinitio study of new, correlated color pigments Anna Galler, Silke Biermann Conventional color pigments used in plastics, ceramics, paint or coatings often contain toxic heavy metals. Recently, the search for nontoxic and environmentallybenign alternatives has led to the experimental discovery of several new pigments, among them blue YIn_{1x}Mn_{x}O_{3} and several rareearth fluorosulfides. Here, we present first results of a theoretical study of these compounds by means of combined density functional and dynamical meanfield theory. 

G70.00334: Structural, vibrational, electrical and optical properties on Crdoped LaAlO_{3} ROMUALDO SANTOS SILVA JUNIOR, Rafael Silva Gonçalves, Petrucio Barrozo da Silva The oxides with perovskitetype structure have been largely studied in last decades. This classes of materials show a large variety of properties such as ferroelectricity, superconductor, multiferroic, transparent conductor oxides among other properties. The perovskite compound LaAlO_{3} has been used as a substrate in many applications. The high dielectric constant observed in this compound is ideal to reduce the loss of energy in devices working at high frequency. In this work, we will report the structural, vibrational, electric and optical of Crdoped LaAlO_{3} ceramics produced by combustion method. We observe a structural phase transition from rhombohedral to an orthorhombic structure with the increase of the Cr amount. It was possible to observe a reduction of the optical bandgap as well as a reduction of the resistivity of the compound. The Raman spectrum as a function of temperature reveals the nature of the structural transition in this compound. The change of the Cr amount can be used to produce new color pigments range from orange/yellow to green/blue. 

G70.00335: Molecular influence on dynamic stiffening of synthetic polyurethanes through laserinduced supersonic microscale impact tests Yuchen Sun, David Veysset, YouChi Mason Wu, Alex J Hsieh, Steven E Kooi, A A Maznev, Jan W Andzelm, Timothy M Swager, Keith Adam Nelson Highstrainrate response is an important characteristic of protective elastomers. To discern the molecular influences on dynamic stiffening in polyurethane (PU), we synthesized twocomponent PUs from poly(tetramethylene oxide) (PTMO) and either hexamethylenediisocyanate (HDI) or 4,4’methylenediphenyldiisocyanate (MDI). From dynamic mechanical analysis, HDIPU displays semicrystallinity while MDIPU appears amorphous. We also synthesized threecomponent PUs with the chain extender butanediol (BD) to introduce segmented hard domains. We performed supersonic microscale impacts with a laserinduced particle impact test in which a silica microsphere is accelerated up to ~1000 m/s. The impact is recorded with micron spatial resolution and nanosecond temporal resolution on an ultrahighspeed camera. In a velocity range of 50 to 1000 m/s, we show that MDIPU exhibits greater dynamic stiffening than HDIPU. We hypothesize that greater intermolecular hydrogen bonding in MDIPU plays an important role. Finally, we discuss the role of segmented hard domains in dynamic stiffening of polyurethanes. 

G70.00336: Anomal behavior of tellurium under pressure Jaime Oliveira, Marcus Moutinho, Carsten Enderlein, Elisa BaggioSaitovitch Elemental tellurium is a small badgap semiconductor with a unique chiral crystal structure and a spin texture of the valence bands, which allows inparallel currentinduced magnetization of pdoped samples. Under pressure the band gap narrows and the structure of the valence band changes from a narrow camelback close to the Hpoint to a single maximum with radial spin texture. Here. we present a theoretical and experimental study of the lowtemperature behavior of the chemically extremely pure, but doped by vacancies, tellurium under pressure. We identify an anomaly at low temperatures, which is related to the orbital structure of the vacancy states and the respective spin texture. The pressure induced change of the valence band leads to the emergence of a change of the orbital structure of the vacancies, effectively leading to an exotic quantum critical point. At one side of the transition strong weak antilocalization is observed, which is consistent with our DFTcalculations, which show a change in spin texture. 

G70.00337: Structural and dynamic properties of Fe(1x)Sx melts at core conditions Aldemar De Moya Camacho, Guillaume Morard, Carlos Pinilla Earth's core is subjected to conditions of 320350 GPa and 50006500 K. The core is lighter than the density of pure iron by around 5% to 10%. In addition, the density jump between inner and outer core is 4.5%, being too large to be explained by simple solidliquid phase transitions. Because of this, it has been suggested that the outer and inner core contain a percentage of light elements (510wt% and 23wt% respectively). These light elements affect processes from core’s dynamics to recrystallization of the inner core. One of the candidates to be part of the core is Sulphur. In this work, we used abinitio Molecular Dynamic methods to study structural and dynamical properties of liquid Fe_{(1x)}S_{x} alloys with S concentrations from 5.8 to 16wt%. We looked at the behavior of structural properties as a function of x, P and T as well as to provide information on diffusion and viscosity coefficients. A PVT equation of state for melts whose S concentration falls within the values for the outer core predicted by the PREM model is reported. We find density values in agreement with other theoretical and experimental results and show that concentrations between 1012wt% of S agree with the densities expected for the outer core. 

G70.00338: Anisotropy in shock compression of different polymorphs of SiC Nilanjan Mitra, Dipak Prasad High hardness and melting point makes SiC an important ceramic material having wide application in defense industry. Typically, SiC utilized for armor and or other applications in defense is a polycrystal having different polymorphs and with numerous defects and thereby the properties of these materials have significant scatter. It can be quite anticipated that the response of the polymorphs of SiC exhibit significant differences in response. In this study anisotropy in shock Hugoniot response of SiC is shown not only amongst the different polymorphs but also between different orientations of the same polymorph. It is expected that this molecular dynamic study will lay the fundamental grounds explaining the scatter is experimental observations of SiC under different loading conditions. However, it should be noted that the study is only limited to considering pristine single crystal materials with no defects. 

G70.00339: Kinetic Monte Carlo Simulation of Oxygen Diffusion in Yttrium Monosilicate Brian Good Ceramic Matrix Composite (CMC) materials are of interest for use in nextgeneration turbine engines, offering a number of significant advantages, including reduced weight and high operating temperatures. However, in the hot environment in which such components operate, the presence of water vapor can lead to corrosion and recession, limiting the useful life of the components. Such degradation can be reduced through the use of Environmental Barrier Coatings (EBCs) that limit the amount of oxygen and water vapor reaching the component. Candidate EBC materials include Y and Yb mono and disilicates. In order to better understand the diffusion of oxygen in such coatings, kinetic Monte Carlo computer simulations are performed for vacancy mechanism oxygen diffusion in Y monosilicate. Oxygen vacancy formation energies and migration barrier energies are computed using density functional theory, showing that all reasonably short migration paths involve relatively large barrier energies. In addition, the vacancy formation energies are relatively large as well, indicating that intrinsic vacancy concentrations will be small, leading to the conclusion that oxygen permeation associated with vacancymechanism oxygen diffusion will be small in this material. 

G70.00340: An Atomistic Study of the Incorporation and Diffusion of Noble Gases in Silicate Minerals Carlos Pinilla, Alfredo Lora, Neil Allan Trace elements are widely used to unravel magmatic processes and constrain the chemical differentiation of the Earth. Central to this enterprise is understanding the controls on trace element fractionation between solid and liquid phases and thus the energetics of incorporating trace elements into crystals. In this contribution we focus on the incorporation of noble gases into crystals. We use abinitio simulations to study the uptake of noble gases (He, Ne, Ar) into solid silicates. We calculate defect energies of incorporation both at vacancies and at interstitial positions in the solid and use these energies to estimate the total uptake of the noble gases into the crystal as a function of temperature. Such concentrations are found to be very low (10^{3 }and 10^{10 }ppm) for He up to Ar respectively with the noble gases incorporated predicted to be more favorable at intrinsic vacancies or interstitials sites. We also look at the diffusion of these elements within the lattice and estimate activation energies for such processes. Our results support the hypothesis that noble gases have very low solubilities in bulk solid minerals. 

G70.00341: Complicated diffusions of dense hydrogen in accurately predicted liquidliquid phase transition Jiayu Dai, Zengxiu Zhao We present results of extensive calculations of the liquidliquid phase transition (LLPT) in dense liquid hydrogen by pathintegral molecular dynamics simulations. The satisfactory nonlocal density functional rVV10 and the hybrid functional PBE0 are used to improve the description of electronic structure of hydrogen. Within density functional theory calculations, we report the best consistent results to the quantum Monte Carlo and coupled electronion Monte Carlo results so far of the LLPT in dense liquid hydrogen. The critical point at temperature between 1500 K and 2000 K is estimated according to the equation of state. Interestingly, we find that the selfdiffusion coefficients of dense liquid hydrogen exhibit complicated behaviors in the vicinity of the transition point, which can be used as a criterion to diagnose the phase transition, and the firstorder LLPT and metallization of dense hydrogen do not occur simultaneously. 

G70.00342: WITHDRAWN ABSTRACT


G70.00343: A Stochastic approach to thermal DFT Yael Cytter, Daniel Neuhauser, Eran Rabani, Roi Baer Despite progress in observational astronomy, some elements such as the internal composition of planets are still not wellunderstood. A root cause is our limited understanding of matter under extreme conditions (MEC)  pressures in the GPaTPa range and temperatures (T) up to 10^{5} K. Due to the difficulty in preparing MECs, the experimental input is limited, and ab initio calculations are sometimes the only source of information. The KohnSham density functional theory (KSDFT) seems as a reliable and useful tool for obtaining information on MEC. Calculations in finite temperatures, however, are expensive due to the large number of fractionally occupied KS orbitals involved. A stochastic method developed recently^{[1],[2]}, appears to be a fitting approach to this problem. By performing a stochastic trace, the KS Hamiltonian is directly obtained from the density, resulting in a scaling of T^{}^{1}. 

G70.00344: External Electric Field Driving the Ultralow Thermal Conductivity of Silicene Guangzhao Qin, Ming Hu Manipulation of thermal transport (pursuing ultrahigh or ultralow thermal conductivity) is on emerging demands, since heat transfer plays a critical role in enormous practical implications, such as efficient heat dissipation in nanoelectronics and heat conduction hindering in solidstate thermoelectrics. It is well established that the thermal transport in semiconductors and insulators (phonons) can be effectively modulated by structure engineering or materials processing. However, almost all the existing approaches involve altering the original atomic structure, which would be frustrated due to either irreversible structure change or limited tunability of thermal conductivity. Motivated by the inherent relationship between phonon behavior and interatomic electrostatic interaction, we comprehensively investigate the effect of external electric field, a widely used gating technique in modern electronics, on the lattice thermal conductivity (k). Taking twodimensional silicon (silicene) as a model system, we demonstrate that, by applying electric field (E_{z} = 0.5 V/Å) the thermal conductivity of silicene can be reduced to a record low value of ~0.091 W/mK. Our study paves the way for robustly tuning phonon transport in materials without altering the atomic structure. 

G70.00345: QUANTUM INFORMATION, CONCEPTS, AND COMPUTATION


G70.00346: Yield Analysis of Superconducting Qubit Fabrication in KRISS Gwanyeol Park, Jiman Choi, Gahyun Choi, SoonGul Lee, Kibog Park, Woon Song, Yonuk Chong In order to achieve scalable quantum circuits, largescale qubit fabrication capability is essential. We have been working on superconducting transmon qubits, and in this study we will present our process' yield analysis on our waferscale qubit fabriation. Our qubit fabrication uses 3 inch wafers, either sapphire or silicon, and tunnel junctions are made by twoangle evaporation using the Dolan bridge. We checked the tunnel resistances on the wafer at room temperature and we typically get 5 to 6 % standard deviation across the wafer. For targeting, we usually get resistance within 10 % of the target value. We also have a couple of outliers on the wafer, typically less than 5 out of ~100 junctions, in which we need improvements. There are many control parameters to improve the yield and spread, so in the end we will discuss the substrate cleaning, ebeam patterning, deposition and oxidation conditions, which are to be controlled tightly in order to get a robust large scale fabrication process of the Josephson junctions. 

G70.00347: Superconducting qubitqutrit circuit: A toolbox for efficient quantum gates Thomas Bækkegaard, Lasse Bjørn Kristensen, Niels Jakob Loft, Christian Kraglund Andersen, David Petrosyan, Nikolaj T Zinner We propose a superconducting circuit which implements an effective tunable spin chain consisting of a qutrit (threelevel system) coupled to two qubits (spin1/2). 

G70.00348: Enhancement in the crossresonant gate performance Xuexin Xu, Mohammad H. Ansari In this poster we describe how the performance of two qubit gates in a superconducting circuits made of capacitive shunted flux qubits and transmons sharing interaction with a bus resonator, can get boosted up as the direct result of capacitive direct coupling between the qubits. For this aim we consider circuit parameters that allow small capacitive coupling between qubits and after quantizing the circuit Hamiltonian within the dispersive regime we make comparison the gate performance with a typical all transmon circuit. 

G70.00349: Hole spins in Ge/Si nanowires Florian NM Froning, Mirko Rehmann, J Ridderbos, Matthias Brauns, Floris Zwanenburg, Ang Li, Erik P. A. M. Bakkers, Dominik Zumbuhl, Floris Braakman Single hole spins confined in quantum dots (QDs) in Ge/Si core/shell nanowires (NWs) combine several properties which make them potentially very unique qubits. The natural abundance of nonzero nuclear spins in both Si and Ge is small and can be further reduced to a negligible amount by isotopic purification. Furthermore, hole spins have no contact hyperfine interaction due to their ptype wavefunction. These properties make hole spin qubits in Si and Ge resilient against dephasing via interaction with nuclear spins. 

G70.00350: Emission of entangled photons via the biexciton formation and decay in core/shell nanoplatelets Matthew Otten, Xuedan Ma, Patrick Serafin, German Kolmakov, Stephen K Gray Quasitwodimensional nanoplatelets (NPLs) possess fundamentally different excitonic properties from zerodimensional quantum dots including exceptionally narrow spectral features and large lateral carrier mobility. We numerically study carrier dynamics of individual CdSe/CdS NPLs in an optical microcavity and find the emitted photon statistics using the density matrix formalism. We find that, due to formation of biexcitons in an NPL and their subsequent decay, the emitted pairs of cavity photons are entangled at temperatures below 20 K. Under favorable conditions the photon pair can be nearly maximally entangled with the relative photon pair population ~0.5. We also show that secondorder photon correlation (g^{(2)}) can be used as a measure of the photon pair entanglement. At temperatures higher than 20 K, the photon entanglement is suppressed due to dephasing caused by thermal fluctuations. Finally, we discuss possible experiments, in which the NPL generated photon pair entanglement can be observed, as well as potential applications in integrated quantum photonics. 

G70.00351: State Recognization of qubits in TwoDimensional Quantum Dots Arrays with Machine learning Ali Rad Application of quantum dot is not limited to a onedimensional array. For the purpose of quantum computation, we need to deal with a twodimensional array of quantum dots. The technical difficulty of largescale and higher dimensional arrays of quantum dots lies a the grow of parameter space substantially with the number of qubits. fortunately, we are able to use machine learning techniques to recognize the pattern of dots and find the tune parameters more efficiently 

G70.00352: Measurement and advances in hybrid quantum system with P1 centers and superconducting qubits Zhiling Wang, Tianqi Cai, Xiyue Han, Maodong Gao, Hongyi Zhang, Yipu Song, Luming Duan A hybrid quantum system which contains spin ensembles, superconducting resonators and superconducting qubits, has been proposed as a way to realize quantum computer. In the first part of this poster, we coupled substitutional nitrogen centers (P1 centers) in diamond to a superconducting resonator with Zeeman effect. We observed a fast relaxation of spin population on the millisecond scale, which is much faster than the intrinsic spin longitudinal relaxation of P1 centers. By pumpprobe experiments we attributed this process to a cross relaxation among different hyperfine splitted spin subensembles. In the second part, we demonstrate iSWAP gate and CR gate by using a 5qubit quantum processor. The qubit anharmonicity is enhanced by using a parallel capacitor, meanwhile the qubit is still operated in transmon regime. Furthermore, we have proposed a new architecture of scalable superconducting qubits based on ring network structures. This design can efficiently avoid breakpoints of superconducting patterns and significantly improve the robustness of intraconnections of qubits. We will demonstrate a quantum processor based on this architecture, to implement a faulttolerant operating scheme with fourteen transmon qubits, which support reliable logical qubits and universal gates. 

G70.00353: Heralded Bell State of Dissipative Qubits Using Classical Light Xin Zhang, Harold U Baranger Maximally entangled twoqubit states (Bell states) are one of the most exotic states in the quantum world and have important applications from testing quantum foundations to quantum information processing. Here we show that a Bell state can be generated using classical light by coupling two qubits to a onedimensional (1d) waveguide. Even though the steady state of the qubits is a trivial product state with no coherence or entanglement, continuous monitoring unravels the steady state nontrivially such that a Bell state is generated in its trajectories and heralded by a reflected photon. This provides a particularly sharp illustration that information gained by measuring an open quantum system can affect its physical state and lead to surprising and useful results. Further, the specific role of information in our system is explored by including imperfect photon detection as a source of information loss. 

G70.00354: Floquetengineered quantum state preparation in a noisy qubit Eric Boyers, Mohit Pandey, David K Campbell, Anatoli S Polkovnikov, Dries Sels, Alexander Sushkov The ability to manipulate quantum states is important to many areas of quantum science including quantum simulation and computation. Adiabatic evolution is a common strategy for preparing quantum states, but it is slow and susceptible to decoherence. Existing methods for speeding up adiabatic evolution require complex multiqubit gates or are difficult to construct for manyqubit systems. Our approach for constructing approximate fastforward (FF) protocols uses the tools of Floquet engineering utilizing only the interactions in the original Hamiltonian. We apply this approach to a two level system and demonstrate it experimentally using the electronic spin of a Nitrogenvacancy center in diamond. We show that our Floquetengineered FF protocol performs comparably to the conventional FF protocol, achieving target state preparation with an upper bound on infidelity (1F) of 0.01 at the 1σ level. We study the performance of our protocol when external noise acts on the qubit and find that it is significantly more robust than the conventional FF protocol. 

G70.00355: Quantum interpolation for digital quantum simulation Jordan Hines, YiXiang Liu, Ashok Ajoy, Paola Cappellaro Quantum simulation enables understanding complex dynamics with experimentally implementable dynamics. Digital quantum simulation enabled by Trotter expansion finds many applications due to its flexibility and universality. However, Trotter expansion higher than second order requires complicated coefficients that are hard to implement in experiment. Here we present Quantum Interpolation, a new exponential product second order approximation of exponential operators, motivated by realistic experimental limitations. We show that Quantum Interpolation has higher fidelity than the most commonly used second order Trotter expansion without any complicated coefficients. We also present the application of Quantum Interpolation in nano nuclear magnetic resonance imaging. 

G70.00356: Spooky Action at a Distance is Not SpookyIt Is Knowledge: Combining Entanglement And Negative Observation To Show How The EinsteinPodolskyRosen Experiment Works, Not Just How It Doesn’t Work Douglas Snyder EPR considered positive measurement (where there is a physical interaction between the measuring device and the particle measured). EPR did not consider that knowledge is responsible for the effect of one of the entangled particles on the other entangled particle. If they had considered negative measurement (where there is no physical interaction between a measuring device and the particle measured), they would have deduced that knowledge is responsible for the effect of a negative measurement on one particle on the other particle. They would have seen that knowledge is also responsible in the case of positive measurements, that the essence of a positive measurement is that it supplies information just as negative measurements do. A sample experiment has been presented to show how the above points work in practice. Implications for the relationship between knowledge and reality are presented. The term “reality” is substituted for “physical reality” since physical reality is not independent of knowledge. 

G70.00357: Does Unitarity Necessitate That an Entanglement Cannot be Destroyed Until a Measurement of 1 of the Entangled Particles is Made? The Answer Is No. Douglas Snyder The generally held view is that an entanglement of two particles cannot be broken until a measurement is made on one of the entangled particles. One reason given for the above thesis is unitarity. Great empirical evidence does indicate the importance of unitarity in the evolution of the wave function itself and also for the mathematical processes for making a measurement prediction. Both unitarity in wave function evolution before measurement and also the mathematical processes for making measurement predictions are supported by great empirical evidence. The view of entanglement that it cannot be broken until a measurement is made on one of the entangled particles is an extension of the view that a wave function is not destroyed until a measurement associated with the wave function is made. It is proposed that one lose or destroy an entangled particle and any whichway information the particle holds (and that the particle supplies to the other entangled particle before any measurements are made) through the use of a large system interacting with the particle to be destroyed. Whether or not the entangled particles is destroyed in the manner noted is correlated to different distributions of the other entangled particle. 

G70.00358: A singleworld consistent interpretation of quantum mechanics from fundamental time and length uncertainties Luis Pedro GarciaPintos, Rodolfo Gambini, Jorge Pullin Within unitary quantum mechanics there exist global protocols that allow to verify that no definite event an outcome to which a probability can be associated occurs. Instead, states that start in a coherent superposition over possible outcomes always remain as a superposition. We show that, when taking into account fundamental errors in measuring length and time intervals, that have been put forward as a consequence of a conjunction of quantum mechanical and general relativity arguments, there are instances in which such global protocols no longer allow to distinguish whether the state is in a superposition or not. All predictions become identical as if one of the outcomes occurs, with probability determined by the state. We use this as a criteria to define events, as put forward in the Montevideo Interpretation of Quantum Mechanics, analizing in detail the occurrence of events in the case of a particle in a superposition of two different locations. We argue that our approach provides a consistent (C) singleworld (S) picture of the universe, thus allowing an economical way out of the limitations imposed by a recent theorem by Frauchiger and Renner showing that having a selfconsistent singleworld description of the universe is incompatible with quantum theory. 

G70.00359: Review Article on Quantum Entanglement & Growing Quantum Information Aditya Chinchole, Shubham Reddy This paper presents the study on quantum entanglement till date, its applications and the research going on in the quantum communication field.It highlights the work on quantum Satellite "Micius" and the future scope of quantum communication. Quantum Information science is also discussed broadly. EPR paradox and Bell inequalities, quantum measurement theory and conceptual work in quantum interpretations mainly many worlds interpretation and Niels Bohr's copenhagen interpretation are also covered. Future applications of the quantum entanglement including the quantum computers is displayed in this paper. 

G70.00360: Universe’s Order Based on the Quantum Disorder Hassan Gholibeigian One of the central challenge in physics is to understand how the ordered systems in macro scales in the universe can arise and how these systems can be characterized from disordered quantum systems in depth of the matter. 

G70.00361: Counterfactual Assessment of The Quantum Zeno Effect Onofrio Russo, Oktay H Gokce We consider counterfactual measurements of the decay process for an unstable quantum mechanical system. In particular, there is a region during the decay process for which frequent observations or measurements of the initial decay states result in a delay in the decay time. The phenomenon is referred to as the quantum Zeno effect. We contend that this can be achieved counterfactually. 

G70.00362: Topological Ordering in the Majorana Toric Code Ananda Roy, Alexander Ziesen, Fabian Hassler At zero temperature, a twodimensional lattice of Majorana zero modes on mesoscopic superconducting islands has a Z2_{ }topologicallyordered toric code phase. Recently, a Landau field theory was proposed for this system that describes its phases and the different phasetransitions separating them. The system is in the toric code phase as a Mott insulator and a charge2e superconductor. However, the topological ordering is absent in the chargee superconducting phase. While the field theories for the different phasetransitions were obtained in the earlier work, the signatures of topological ordering in the different phases were not investigated in detail. This is the goal of the current work. We describe a lattice gauge theory of the Majorana toric code in terms of a U(1) matter field coupled to an emergent Z2_{ }gauge field. Subsequently, we use a generalized Wilsonloop orderparameter, namely, the equaltime FredenhagenMarcu order parameter, to distinguish between the different phases. Furthermore, we calculate perturbatively the energy gap of the toric code in the presence of Cooperpair tunneling. Our results are relevant for the current efforts to experimentally realize the Majorana toric code. 

G70.00363: Analyzing the Toric Code using HighTemperature Series Expansions Benedikt Andreas Placke, Ananda Roy, Nikolas Breuckmann The decoding of several topological quantum codes (TQC) can be mapped onto statistical physics models (SPM). In this mapping, a successful decoding of the error syndrome of the TQC corresponds to a certain phase of the corresponding SPM. The errorcorrection performance of several TQCs have been analyzed using Monte Carlo (MC) simulations. 

G70.00364: The RyuTakayanagi Formula from Quantum Error Correction: An Algebraic Treatment of the Boundary CFT Helia Kamal In recent years, an interpretation of the Antide Sitter/Conformal Field Theory (AdS/CFT) correspondence in the language of quantum error correction has been developed. This language shines light on several puzzling features of the correspondence and has therefore played a crucial role in advancing our understanding of AdS/CFT. In particular, in a recent work by Daniel Harlow, it is shown that subalgebra quantum erasurecorrecting codes with complementary recovery naturally give rise to a version of quantumcorrected RyuTakayanagi formula that captures the physics of AdS/CFT. In his interpretation, Harlow considers a Von Neumann algebra on the bulk, but assumes a simple tensor product structure on the boundary Hilbert space. In this work, we developed the mathematical framework for extending Harlow's results to the more physical case where a Von Neumann algebra is also given on the boundary CFT. We showed that the resulting code more accurately captures the properties of AdS/CFT. 

G70.00365: Quantum machine learning for electronic structure calculations Rongxin Xia, Sabre Kais Considering recent advancements and successes in the development of efficient quantum algorithms for electronic structure calculations—alongside impressive results using machine learning techniques for computation—hybridizing quantum computing with machine learning for the intent of performing electronic structure calculations is a natural progression. Here we report a hybrid quantum algorithm employing a restricted Boltzmann machine to obtain accurate molecular potential energy surfaces. By exploiting a quantum algorithm to help optimize the underlying objective function, we obtained an efficient procedure for the calculation of the electronic ground state energy for a small molecule system. Our approach achieves high accuracy for the ground state energy for H_{2}, LiH, H_{2}O at a specific location on its potential energy surface with a finite basis set. With the future availability of largerscale quantum computers, quantum machine learning techniques are set to become powerful tools to obtain accurate values for electronic structures. 

G70.00366: Quantum Linear Regression With Regularization Xiaokai Hou, Xi He, Chufan Lv, Dingding Wen, Xiaoting Wang The problem we are trying to solve in this article is how to execute linear regression algorithm with regularization based on quantum mechanics system. In the field of machine learning, linear regression is a powerful tool modeling input and output variables using the least squares function of linear equations. And regularization is a technical method to solve the overfitting phenomenon which can be caused when the training data is lack or not universal. The approach we mainly adopt to transform classical linear regression to quantum version is to construct Hamiltonian containing the training data information. And via HHL algorithm and swap test, we can accomplish the training process and also make a prediction with input variable state. Compared with classical analogue, the quantum linear regression algorithm demonstrates quadratic speed up. 

G70.00367: Decomposable Coherence and Quantum Fluctuation Theorems Erick Hinds Mingo, David Jennings How can one define work on a quantum system without requiring the existence of a classical agent manipulating macroscopic equipment? To answer this question, we formulate the problem as can be done in Newtonian mechanics  by introducing a `weight system' with strict global energy conservation. By allowing a system in an arbitrary pure quantum state to interact with a weight system prepared in a well defined state, we are able to study the structure of `coherent energy transfers'. We then define a coherent work process and show that this is related to the notion of decomposability of a classical random variable. Maintaining the nomenclature, we introduce the notion of decomposable coherence. Furthermore, we show that coherent work processes can only map coherent states to coherent states, and they become classical work processes in a conservative potential as h goes to 0. 

G70.00368: An iterative variational algorithm for optimization on nearterm quantum devices Omid Khosravani Hybrid quantumclassical optimization algorithms have recently attracted interest for applications in the noisy intermediatescale quantum devices (NISQ) era of quantum computing. However, as it has been recently shown by Jarrod McClean et. al. (arXiv:1803.11173v1), many such algorithms could suffer from the issue of Barren Plateaus even at shallow depth circuits, which corresponds to the phenomenon of vanishing of gradients in training classical deep neural networks. Here we introduce a variational method which restricts the entropy of the batch Hamiltonian per circuit complexity and propose an algorithm that attempts to avoid this issue by iteratively recombining the solutions while approaching an optimal solution. Finally we compare the performance of our algorithm with existing variational and quantum approximate optimization algorithms. 

G70.00369: Separating Quantum and Classical Entropies: A unified treatment of quantum and classical information Amro Dodin, Adam P. Willard Information in open quantum systems can be influenced by the presence of classical and quantum sources of uncertainty, complicating the quantification of the information encoded in such systems. By considering classical distributions on quantum state space, quantum and classical uncertainty can be separated, allowing for the simultaneous treatment of quantum (von Neumann) and classical (Shannon) entropies. In this presentation, a method for simultaneously quantifying quantum and classical entropies of quantum ensembles will be presented and the manner in which quantum operations (e.g. measurements and dynamical channels) transform one form of entropy into another will be discussed. 

G70.00370: Superadiabatic quantum friction suppression in finitetime thermodynamics Shujin Deng, Aurelia Chenu, Pengpeng Diao, Fang Li, Shi Yu, Ivan Coulamy, Adolfo Del Campo, Haibin Wu Optimal performance of thermal machines is reached by suppressing friction. Friction in quantum thermodynamics results from fast driving schemes that generate nonadiabatic excitations. The farfromequilibrium dynamics of quantum devices can be tailored by shortcuts to adiabaticity to suppress quantum friction. We experimentally demonstrate frictionfree superadiabatic strokes with a trapped unitary Fermi gas as a working substance and establish the equivalence between the superadiabatic mean work and its adiabatic value. 

G70.00371: Optimal Quantum Approximate Optimization Algirithm: Success Probability and Runtime Dependence on Circuit Depth Murphy Yuezhen Niu, Sirui Lu, Isaac Chuang Due to its simplicity, universality and optimality, quantum approximate optimization algorithm~(QAOA) has been considered a useful nearterm algorithm for conducting classical optimization and quantum simulation. We answer an open question of how the success probability and runtime of QAOA depend on the quantum circuit depth by focusing on a specific problem: state transfer in onedimensional spin chain. We provide an analytic proof on the success probability scaling by leveraging the spectral property of the XY Hamiltonian. We show both analytically and numerically a Grover like quadratic dependence on the circuit depth in the short circuit depth limit and an exponential scaling in the large circuit depth limit. We prove the perfect state transfer needs O(N) time using LiebRobinson bound for a spin chain of length N and confirm this numerically. 

G70.00372: Locally accurate matrix product state approximations with constant bond dimension for ground states of gapped 1D models Alexander Dalzell, Fernando Brandao The numerical success of the DMRG method has been explained by the observation that it can be recast as a variational algorithm over the set of matrix product states (MPSs) with a specified bond dimension. The bond dimension need only increase like a polynomial in the number of sites on the 1D chain to guarantee that some element of the MPS manifold represents a good approximation to the ground state of a given gapped local Hamiltonian. But DMRG is often successful even for very small values of the bond dimension. We provide a partial justification for this success by showing that the MPS bond dimension may be kept constant as the number of sites increases if one desires an approximation that is good only in a local sense, that is, the reduced density matrix of the true ground state is close to that of the approximating MPS when all but a constant segment of the chain is traced out. While a similar result was known for matrix product operator (MPO) approximations, MPSs are superior to MPOs as an ansatz for variational algorithms since verifying that a certain MPO is positive (and thus represents a valid quantum state) is difficult, whereas MPSs do not have this issue. 

G70.00373: Quantum enhanced metrology with noise assistance and error correction Yu Chen, Haidong Yuan Quantum metrology has seen various important applications in science and engineering, ranging from atomic frequency estimation to gravitational wave detection. It has been shown that quantum resources can outperform their classical counterparts as regard to improving the precision of parameter estimation. However, there is inevitable difficulty in manipulating a quantum system because the system keeps leaking out information to the environment that it is coupled to, making superiority brought by the ``quantumness" disappear beyond decoherence time. Therefore, it is critical to protect the system from noise, which can be achieved by means of adding control signals. 

G70.00374: Dark matter search with the Cosmic Axion Spin Precession Experiment (CASPEr) Deniz Aybas The nature of dark matter is an open question in fundamental physics. The Cosmic Axion Spin Precession Experiment (CASPEr) is a laboratory scale search for the axion as a dark matter candidate [D. Budker, et al., Phys. Rev. X 4, 021030]. The range of axionlike dark matter masses to which CASPEr is sensitive extends from feV to μeV with sensitivity beyond current astrophysical limits. CASPEr uses Nuclear Magnetic Resonance (NMR) techniques and precision magnetic sensors, such as Superconducting Quantum Interference Devices (SQUIDs). The current status and preliminary results of CASPEr will be presented. 

G70.00375: Josephson Metamaterial with a Tunable Kerr Constant Matthew Bell, Wen Ting Hsieh Superconducting circuits rely heavily on the nonlinearity inherent in Josephson Junctions. The magnitude of this nonlinearity can be set either at fabrication or tuned with a superconducting quantum interference device (SQUID). Generally, the sign of the Kerr coefficient in the cosine energy phase relation for Josephson junctions cannot be tuned. Here we will present a unit cell design of a metamaterial which allows the Kerr coefficient to be tuned over a wide range in magnitude and can even change sign from positive to negative. Experimental results will be presented showing agreement with theory for the Josephson chain. We will also demonstrate how this metamaterial can be applied to recent efforts in realizing large superinductors and efficient travelingwave parametric amplifiers (TWPA), two applications which have heavily relied on series arrays of Josephson junctions. 

G70.00376: Practical algorithm for determining Hamiltonian identifiability Xiaoyang Huang, Roberto Gauna, Akira Sone, Paola Cappellaro We demonstrate a practical algorithm for determining the identifiability of Hamiltonian parameters with local accessibility. We consider the problem of estimating the parameters of the Hamiltonian of onedimensional spin chain systems with nearestneighbor interaction and assume that we only have access to a single quantum probe coupled to the target system. We demonstrate a practical implementation of Hamiltonian identifiability by the eigensystem realization algorithm and Gröbner basis. Furthermore, we also provide a practical code to estimate the Hamiltonian parameters from the experimental results. XH and RG equally contributed to this work. 

G70.00377: RoomTemperature Quantum NonDemolition Measurement Enhanced by Machine Learning Mo Chen, YiXiang Liu, Paola Cappellaro Projective measurements of qubits are a key resource for quantum computation. For qubits based on NitrogenVacancy centers in diamond at roomtemperature, projective measurement has been achieved using quantum nondemolition measurement schemes enabled by an ancillary qubit. In this scheme, the nuclear spin (qubit) state is repetitively read out by a mapping to the NV electronic spin (ancillae) until the photon number distribution from one qubit state is distinguishable from the other in a single shot. High readout fidelity requires a few to tens of thousands of repetitive readouts. This, unfortunately, imposes a heavy time overhead to any quantum algorithms. The readout time is on the same order of the decoherence time of the best physical qubit in the system, preventing feed forward protocols. In this work, we describe a method to improve the single shot readout fidelity using machine learning with information already recorded, but traditionally discarded in the experiment. Hence, our method does not impose an additional experimental time penalty. Combined with photonic structures that enhance photon collection efficiency, we expect this technique will enable roomtemperature feed forward quantum information processing. 

G70.00378: Integrated Fibre Detection Architectures for Distributed Quantum Magnetometry Christopher Foy, Shai Maayani, Dirk R. Englund, Yoel Fink Distributed magnetic sensing over large distances is of interest for a diverse range of applications including remote detection of ferrous metals, geophysics, and biosensing. Unfortunately, the capability to measure magnetic fields over large distance is unrealized. Here, we address this problem by introducing a diamond spin magnetometer directly embedded into an optical fibre alongside highperformance optoelectronic devices. Our magnetometer relies on the translation of an ensemble of nitrogen vacancy (NV) centers in microdiamonds within a microfluidic channel. The NV’s spindependent fluorescence is detected by embedded Si photodiodes. This device allows for distributed magnetic field measurements along a 300 meterlong fibre with a DC sensitivity of 81 nT Hz1/2. We will discuss next steps and the deployment of this technology. 

G70.00379: Singlephoton switching inside a polarizatcavityionselective Jeremy Flannery, Michal Bajcsy We propose a scheme for singlephoton switching that employs the phenomenon of vacuum induced transparency (VIT) and an ensemble of a threelevel atoms in a polarizationselective cavity. In this system, light of one polarization (H) couples to one of the atomic transitions with high singleatom cooperativity, while the orthogonal polarization (V) couples to the other atomic transition. When both a weak probe and the cavity mode are resonant with their respective transitions, the otherwise opaque system becomes transparent to the probe through VIT. 

G70.00380: Timeresolved probing of manybody states in circuitQED systems Kirill Shulga, Ihor Vakulchyk, Mikhail Fistul, Yasunobu Nakamura CircuitQED quantum simulators based on superconducting circuits provide a tool to study manybody phenomena in strongly interacting qubit systems. In this work, we perform experimental studies of timeresolved dynamics of superconducting qubit arrays embedded in a superconducting resonator. We demonstrate an occurrence of manybody Rabi oscillations and complex dynamics in the dispersive and the resonant regimes. At variance with single qubit Rabi oscillations, the manybody Rabi oscillations emerge as the amplitude of applied microwave pulse exceeds the critical value. The magnetic field tunable crossover between manybody and single particle Rabi oscillations is obtained. We also experimentally explore a possibility to realize a time crystalline order in an array of superconducting qubits by applying periodic sequence of pulses with excitation of nonequilibrium states in the system. 

G70.00381: Fast dispersive, Purcellfiltered measurement and reset using smooth and simple analytic pulse shapes Lukas F Buchmann, Felix Motzoi, Christian Dickel We present a dispersive, measurement pulse shaping technique that allows for arbitrarily fast quantum nondemolition, singlequadrature measurements of nonlinear systems and unconditionally leaves the measurement resonator empty. Leftover cavity population from short measurements with square or composite digital pulses can be suppressed using instead simple smooth pulse shapes from an analogous family of DRAG shapes; here, it can be derived exactly for arbitrarily many measured modes. The results are easily generalizable, including singleshot, singlequadrature, measurements of multiqubit and multistate (leakage) systems. One can also straightorwardly incorporate Purcell filter cavities, which can be depopulated simultaneously via the same technique. Finally, we show how to apply the technique to cascaded cavity networks, e.g. for fast remote entanglement generation, or in nondispersive singlephoton networks, and discuss applicability to singe flux quantum (SFQ) readout. 

G70.00382: Deep LearningBased Prediction and Optimal Sequential Measurement of a Quantum Dot Dominic Lennon, Hyungil Moon, Michael Osborne, Leon Camenzind, Liuqi Yu, Dominik Zumbuhl, George Andrew Davidson Briggs, Edward Laird Spin qubits defined in quantum dots are promising for creating a scalable quantum computer. However, they are timeconsuming to characterise, and as the size of these systems increases, this task will become intractable without the aid of automation. We present a machine learning algorithm that decides where to measure next and demonstrate it operating on a real quantum dot device in realtime. The algorithm utilises a probabilistic deepgenerative model to make reconstructions of a full current map given partial measurement and information theory to select the most informative measurements to perform next. 

G70.00383: Tunnelingnoiseinduced spin dephasing of two electrons in an arbitrarily detuned double quantum dot Peihao Huang Recent progress enables operations of a twoqubit gate for two electron spin qubits in a double quantum dot (DQD), which is an important step towards scalable semiconducting quantum computing. In an asymmetric DQD, it has been shown that 1/f chargenoiseinduced tunneling noise can dominate spin decoherence under condition relevant in a twoqubit experiment. Here, we study spin decoherence due to 1/f charge noise for two electrons in a DQD with arbitrary detuning. We show that, in a symmetric DQD, chargenoiseinduced tunneling noise can have a profound contribution compare to detuning noise, where the contribution of detuning noise is vanished due to the destructive interference while the contribution of tunneling noise remains finite. We study the spin decoherence for various detuning and tunneling and discuss its consequence on the figure of merit of a twoqubit gate. 
(Author Not Attending)

G70.00384: 12photon entanglement and scalable scattershot boson sampling with optimal entangled photon pairs from parametric downconversion HanSen Zhong, Yuan Li, Wei Li, LiChao Peng, ZuEn Su, Yi Hu, YuMing He, Xing Ding, Weijun Zhang, Hao li, Lu Zhang, Zhen Wang, Lixing You, Jun Zhang, XiLin Wang, Li Li, YuAo Chen, NaiLe Liu, ChaoYang Lu, JianWei Pan Spontaneous parametric downconversion (SPDC), one of the most popular entanglement source, enable thousands of quantum optics experiment during the past few decades. We have been devoted on optimizing the property of SPDC. One of the major task is to design a near perfect SPDC entanglement source with high indistinguishability and high efficiency simultaneously. Recently, an SPDC entangled photon pair source of which the heralding efficiency is 97% and the indistinguishability is 96% has been developed. 

G70.00385: Investigating the Effectiveness of MeasurementDeviceIndependent Quantum Key Distribution with Weak Coherent Pulses Annika Dugad, Joseph Chapman, Andrew Conrad, Paul G Kwiat, Daniel J Gauthier Quantum key distribution (QKD) is a quantum cryptographic task that allows a random secret key to be generated and communicated between two parties in the presence of an eavesdropper. Although QKD systems are theoretically foolproof and completely secure according to the laws of quantum mechanics, many security loopholes have been found in practice. Measurementdeviceindependent quantum key distribution (MDIQKD) improves upon previous QKD systems by removing all detector sidechannels, therefore rendering many of the loopholes obsolete. However, in order to successfully implement MDIQKD, the sources (representing the two communicating parties) must be indistinguishable. We will be implementing MDIQKD with two independent sources of light coming from attenuated laser pulses, or resonant cavity LEDs; as a result, the sources will be rigorously tested and characterized to determine how indistinguishable they truly are. 

G70.00386: Why We Should Be Skeptical of Quantum Computing Alan M. Kadin It is widely believed that quantum computing is on the threshold of practicality, with performance that will soon surpass that of classical computing. On the contrary, it is argued that both the present and the future of quantum computing may be highly uncertain, for the following reasons: 

G70.00387: Singlechannel Hadamard gate through singlephoton Raman Scattering in Chiral Quantum Nanophotonics Zihao Chen, Yao Zhou, JungTsung Shen Hadamard gate (Hgate) is indispensable to constitute complete sets of logic gates for universal quantum computing. Practical implementations can be classified into atom and photonbased. While atombased techniques are rather mature by employing consecutive electromagnetic pulses to drive qubit rotations on Bloch sphere, it is of limited coherent time, and may not be compatible with photonbased quantum communication protocol in scalable quantum internet blueprint. Henceforth, photonbased implementations may play significant roles, which are typically realized by using linear optical elements. However, such schemes require different photonic channels to accommodate binary qubits, thus resulting in limited spatial utility. 

G70.00388: Quantum computing methods for electronic states of the water molecule Teng Bian, Daniel Murphy, Rongxin Xia, Ammar Daskin, Sabre Kais We compare recently proposed methods to compute the electronic state energies of the water molecule on a quantum computer. The methods include the phase estimation algorithm based on Trotter decomposition, the phase estimation algorithm based on the direct implementation of the Hamiltonian, direct measurement based on the implementation of the Hamiltonian and a specific variational quantum eigensolver, Pairwise VQE. We explain how each method works and compare the simulation results in terms of gate complexity and the number of measurements. In conclusion, among methods based on the phase estimation algorithm, the second order direct method provides the most efficient circuit implementations in terms of the gate complexity. With large scale quantum computation, the second order direct method seems to be better for large molecule systems. Moreover, Pairwise VQE serves the most practical method for nearterm applications on the current available quantum computers. Finally, the possibility of extending the calculation to excited states and resonances is discussed. This work is posted on arXiv: Quantum computing methods for electronic states of the water molecule. 

G70.00389: Quantum Bernoulli Factories in a Classical Setting Thomas Hebdige, David Jennings Recently a novel quantum advantage over classical information processing has been developed in the context of randomness processing, under the title of “Bernoulli factories”. Bernoulli Factories find modern application in classical Bayesian statistics, such as in genetics when one encounters intractable likelihood functions. However, since quantum Bernoulli factories are more powerful than their classical counterparts, an open question is if this advantage can be exploited within the classical setting. Here we present work towards an implementation of a quantum Bernoulli factory on nearterm quantum devices, and contrast this formalism with the quantum resampling protocol of Webb & Kitaev. 

G70.00390: Scaling Hypothesis of Spatial Search on Fractal Lattice Using Quantum Walk Shohei Watabe, Shu Tamegai, Rei Sato, Tetsuro Nikuni We investigate a quantum spatial search problem on a fractal lattice. A recent study for the Sierpinski gasket and tetrahedron made a conjecture that the dynamics of the search on a fractal lattice is determined by spectral dimension for the optimal oracle calls, and not by the fractal dimension [A. Patel and K. S. Raghunathan, Phys. Rev. A 86, 012332 (2012)]. We tackle this problem for the Sierpinski carpet, and we find that our simulation result may support the conjecture. We also propose a scaling hypothesis of oracle calls for the quantum amplitude amplification in a fractal lattice, which is given by the Euclidean dimension, fractal dimension, spectral dimension, and the scale factor of a fractal lattice. We have confirmed that our scaling hypothesis holds in the Sierpinski carpet, gasket, and tetrahedron. 

G70.00391: Quantum Theory of Entanglement and Brain Physics Shantilal Goradia Despite decades of hard work by PenroseHameroff Hypothesis (ORCH OR) about consciousness, the hypothesis is not universally accepted. We formulate our hypothesis dubbed as “orchestrated subjective experience (ORCH SE)” based on our theory of quantum gravity (explaining the abundance of dark matter) to address the subject disconnect in our recent article, “Quantum Theory of Entanglement and Brain Physics,” in an open minded, OPEN ACCESS Journal of Clinical Reviews and Case Reports 2018, Volume 3, Issue 7. Since dark matter exists in the universe, there is no reason why it would not be present in the brain, to some extent. 

G70.00392: FLUID DYNAMICS


G70.00393: ABSTRACT WITHDRAWN


G70.00394: Pulsatile Flow Through MultiCoupled Idealized Renal Tubules: FluidStructure Interaction and Dynamics Pathologies Niksa Praljak, Andrew H Resnick Kidney tubules are known to have flowsensing structures, yet information about the flow itself is very fragmentary. Our aim is to generate a biomechanical model for analyzing fluid flow within an elastic kidney tubule when the driving pressure is pulsatile. We created finiteelement numerical models of coupled kidney tubules and determined the flow dynamics and wall stresses over a range of driving frequencies and wall compliances. The results form a basis for including elastohydrodynamic coupling by neighboring tubules via the interstitium. As well, the results analyze how elastic tubules interact with different frequency phases that alter the hydrodynamics of the fluid in the interior and exterior. Overall, we are interested in exploring the idea of ‘dynamics pathology’ to better understand the progression of certain kidney diseases, for example, Polycystic Kidney Disease. 

G70.00395: Foam films and liquid bridges formed by aqueous sodium naphthenate solutions Chrystian Ochoa, Elizabeth John, Jelena Dinic, Vivek Sharma Sodium Naphthenates found in crude oils can act as surfactants and selfassemble in aqueous solutions to form micelles and liquid crystals. Understanding and controlling the drainage kinetics of thin films is an important problem that underlies the stability, lifetime and rheology of petroleum foams and emulsions. Here, we show that foam films formed by aqueous solutions of sodium naphthenates exhibit stepwise thinning or stratification. We utilize Interferometry, Digital, Imaging, Optical Microscopy protocols, previously developed by our group, to investigate the drainage and stratification in micellar foam films (< 100 nm) with high spatial (thickness < 10 nm) and temporal resolution (< 1 ms). We determine how the concentration of added sodium naphthenates influences the nanoscopic topography, stratification kinetics and step size of foam films. Finally, we show that visualization and analysis of capillarydriven thinning and pinchoff dynamics of the columnar neck in an asymmetric liquid bridge created by drippingontosubstrate (DoS) of sodium naphthenate solutions can be used for characterizing the change in shear viscosity, extensional viscosity and microstructure in such surfactant solutions. 

G70.00396: Holographic Rheology of Viscoelastic Fluids in Microfluidic Geometries Siddhartha Gupta, Siva A Vanapalli To explore the kinematics and rheology of viscoelastic flows it is critical to map threedimensional (3D) velocity fields. The 3D flow information can be used for understanding phenomena such as elasticitydriven instabilities, slip and shearbanding. Digital holography microscopy (DHM) with particle tracking velocimetry (PTV) is an interferometry technique which can provide realtime 3D flow information by recording holograms of the flow. We demonstrate the robustness of holography in characterizing the kinematics of polymeric and Newtonian fluids in rectilinear channels, contractionexpansion and curved microchannels, which provide for shear, extensional and curvilinear flow behavior respectively. Using DHMPTV, we recover the full 3D velocity field which is in good agreement with analytical results and flow simulations. Additionally, we demonstrate a digital holography driven rheology (DHR) approach for quantifying shear viscosity curves of complex fluids in thinslit geometries. The DHR approach does not make apriori assumptions about material properties and is thus independent of slip which has been found to affect narrow gap rheology. In sum, we conclude that digital holography microscopy has powerful applications for investigation of complex fluids in complex geometries. 

G70.00397: Effects of nanoparticles on the stability of polymer fibers Taejin Kwon, Bong June Sung Soft matters in confinement may deform easily upon small perturbation. Especially, polymer fibers are unstable due to a large surface area. Recent studies showed that the addition of nanoparticles (NPs) could control the stability of polymer fibers. It remains elusive how NPs would affect the disruption of polymer fibers. In this work, we perform molecular dynamics simulations for polymer fibers with NPs of different interaction types. We prepare unstable polymer fibers that disrupt into globules. We find that upon the addition of NPs, the disruption of fibers is hindered and the breakup time (τ_{b}) of polymer fibers increases. We find that polymer fibers with NPs are more likely to retain their morphology. The free energy barrier between the fiber and the globule would increase due to NPs. The mechanism for the stability differs for the different interaction types of NPs. When the interaction between polymers and NPs is attractive (nonattractive), τ_{b} increases (decreases) with a decrease in temperature. We show that different spatial arrangement of NPs leads to the different temperature dependence of τ_{b}. 

G70.00398: Experimental Investigation of Droplets Impacting on Inclined Heated Surfaces with Varying Wettability Qiang Ma, Xiaomin Wu Droplets impacting on heated surfaces is a common phenomenon in spray cooling, which can remove very high heat flux. Since the surface wettability has a significant effect on the heat transfer performance by directly changing the droplet spreading, rebounding and boiling behaviors, it has drawn much attention. However, the surface roughness changes simultaneously when changing the surface wettability in most researches. Thus, the influence factors of wettability and roughness are coupled. In this work, the test surfaces were fabricated by spraycoating a thin film on the aluminum substrates and the roughness of each surface is small enough. Therefore, the influence of wettability on droplets impacting on inclined heated surfaces have been experimentally studied. The experiments were carried out with different inclination of 0^{o}, 30^{o} and 60^{o}, with different surface temperature from 100^{o}C to 400^{o}C and with different surface contact angle of 10^{o}, 78^{o}, 95^{o} and 122^{o}. The droplet spreading, rebounding and boiling behaviors have been observed by a high speed camera. The droplet spreading factors, advancing and receding contact angles have been measured and the droplet boiling regimes have been identified. 

G70.00399: Simulation of Droplet Impact on a Spherical Surface Xin Liu, Xuan Zhang, Jingchun Min Droplet impact phenomenon is widely found in nature, production and life. Due to the complexity of the actual surface structures, the droplet may impact not only on a flat surface but also on surfaces of various shapes and the one typical example is a sphere. In this study, the droplet impact process on a spherical surface is simulated using the VOF multiphase model coupled the dynamic contact angle model, which is compared with our experimental data to verify the model. Based on this model, the impact processes of droplets with different We numbers on spherical surfaces with different diameters and contact angles are simulated. The results indicate that the maximum spreading factor increases significantly with the increase of We and the decrease of contact angle while it is little influenced by the sphere diameter. The droplet may break up at the spreading or receding stage during the whole impact process. Compared with impacting on the flat surface, the droplet is more likely to break up when impacting on a sphere due to the gravity and the critical We number for breaking up is smaller. The droplet breakingup diagram is obtained, which provides reference for the droplet impact study. 

G70.00400: Coalescence Dynamics of NearCritical Sulfur Hexaflouride in Microgravity Christian Hawkins, Ana Oprisan, Daniel A Beysens, Yves Garrabos, Carole Lecoutre Critical fluids have a variety of applications from manufacturing hightech materials to industrial lubrication and extracting oils from foods. Phase separation of critical fluids cannot be studied on earth due to the increase in compressibility near the critical point and stratification of fluids by density in gravity. We used direct imaging to record snapshots of phase separation that takes place in sulfur hexafluoride (SF6) in weightlessness conditions on the International Space Station (ISS). The system was at liquidvapor equilibrium slightly below the critical temperature and further cooled down by a 0.2mK quench that produced a new phase separation. Both full view and microscopic views of the direct observation cell were analyzed to determine the evolution of the radii distributions. In addition, in microscopic view, we measured the diameter of droplets and bubbles in the system throughout multiple coalescence events leading to further support of the coalescenceinducedcoalescence model. 

G70.00401: Strategies for Microparticle Manipulation by Rectified Inertial Forces Siddhansh Agarwal, Bhargav Rallabandi, Sascha Hilgenfeldt Oscillating interfaces in a liquid give rise to inertial effects that manifest as multiple physical phenomena on slower (steady) time scales, including streaming flow and force actuation on immersed particles. While these effects have traditionally been treated separately, we develop a timescale separation formalism that puts streaming motion of fluid elements and rectified motion of particles on the same footing. 

G70.00402: Throughput enhancement of parallel step emulsifier devices by shearfree and efficient nozzle clearance Elad Stolovicki, roy ziblat, David A Weitz Step emulsification is an attractive method for production of monodisperse drops. Its main advantage is the ability to parallelize many step emulsifier nozzles to achieve high production rates. However, step emulsification is sensitive to any obstructions at the nozzle exit. At high production rates, drops can accumulate at nozzle exits, disturb the formation of subsequent drops and impair monodispersity. As a result, parallelized step emulsifier devices typically do not work at maximum productivity. Here a design is introduced that parallelizes hundreds of step emulsifier nozzles, and effectively removes drops from the nozzle exits. The drop clearance is achieved by an open collecting channel, and is aided by buoyancy and does not apply shear on forming drops. The clearance method avoids the use of a continuous phase flow for drop clearance. The method works well for a wide range of drops, sizing from 30 to 1000 µm at production rates of 0.03 and 10 L per hour and achieved by 400 and 120 parallelized nozzles respectively. 

G70.00403: WITHDRAWN ABSTRACT


G70.00404: Experimental investigation into a nanoparticle based direct absorption solar oscillating heat pipe Haie Yang, Haichuan Jin, Guiping Lin, Dongsheng Wen Nanoparticlebased volumetric solar absorption has been shown to be an effective technique to realize efficient solar harvesting. However, most of such systems under study are stationary and cannot realize solar energy transport, which limits their potential applications to a large extent. A novel idea of using directive absorptive nanofluids in oscillating heat pipes (OHP) is investigated in this work, which would achieve efficient solar energy capture and transportation simultaneously without the use of any additional pumping power. The influence of a variety of parameters such as nanoparticle type, nanoparticle concentration, nanofluids filling ratio and solar radiation intensity on the performance of OHPs are investigated. Very high effective thermal conductivity is observed. It is found that strong absorption of solar energy, efficient vapor generation inside the OHP and proper configuration of the OHP should be responsible for the efficient operation of this system. 

G70.00405: Fluidic wrench: Precise control over the position and orientation of anisotropic colloids using fluid flow Dinesh Kumar, Anish Shenoy, Songsong Li, Charles Schroeder A grand challenge in the field of directed assembly is to precisely assemble chemically and structurally distinct anisotropic particles into functional hierarchical structures. Such complex assembly schemes will require precise control over both the position and orientation of individual rods. In this work, we demonstrate simultaneous control over the 2D centerofmass position and orientation of anisotropic colloidal particles using only fluid flow. We use a 4channel microfluidic device with a modelpredictive control scheme to generate a flow pattern that translates and rotates rodlike particles from their initial state to a final desired position and orientation. Unlike alternative techniques that exploit intrinsic material properties of particles (e.g. index of refraction, magnetic properties, surface charge) to control position and orientation, our method imposes no restrictions on the physical or chemical properties of the particles, and hence, can be used for rods of any material and size, assuming they can be imaged. Moving forward, this approach could be further engineered to achieve fluidicdirected assembly of asymmetric objects on a meso to microscale level. 

G70.00406: Microporosity Evolution and PowderPowder Interaction in Selective Laser Melting Process Jiqin Li, Lu Li, TaiHsi Fan Additive manufacturing in aerospace and biomedical applications is challenging due to the need of superior quality and liability of end products. A critical concern about the process is the formation of surface defects due to incomplete melting of powders and gas trapping between powders, which significantly weakens the mechanical performance of the raw products. Better understanding of the process dynamics can help to mitigate the defects and determine process control parameters. We present phasefield modeling of the powderpowder interaction and the formation of micropores during selective laser melting of pure titanium powders. The solidliquid phase transition is coupled with thermal transport, capillary flow, and liquidgas interfacial deformation. The change of morphology and the evolution of pores highly depend on the interplay of the fusion dynamics, configuration of powders, and laser control parameters. 

G70.00407: Gravity and Flow Effects on Coarsening Dynamics in CrystalLiquid Mixtures TaiHsi Fan, Jiqin Li, Elizabeth Soha Coarsening of crystals can be driven by cooling, Ostwald ripening, or interfacial kinetics in crystalliquid mixtures. The relevant phenomena appear in many manufacturing processes involving metals and alloys, or nonmetallic materials. The degree of coarsening determines the size of crystals and microstructural pattern, and thus understanding coarsening dynamics is important in controlling the uniformity of microstructure and properties of the end products. We present a phasefield theoretical framework to investigate coarsening dynamics in symmetric and asymmetric binary systems. The phase transition and microstructure evolution are coupled with fluid flow, trajectory motion of the crystals, thermophysical properties of the materials, interfacial energy, and the relevant heat and mass transport phenomena. Specifically, we focus on crystal morphology and the fluid flow induced by density variation and gravity acceleration. The flow and collective motion of crystals also influence the heat and mass transfer around the interstitial space between crystals and should be resolved simultaneously. The theoretical analysis and 2d computational results based on spectral method will be presented. 

G70.00408: Geometry and Topology of Collective 2D Vortex Dynamics Alexander Bogatskii, Pavel Wiegmann We consider the coarsegrained dynamics of many quantized chiral vortices on a 2D surface. 

G70.00409: Ellipsometric Characterization of Monolayer MoSe_{2} from 31 to 300K Hoang Tung Nguyen, Han Gyeol Park, Tae Jung Kim, Van Long Le, Farman Ullah, Yong Soo Kim, MaengJe Seong, YoungDong Kim The layered transition metal dichalcogenides (TMDCs) has recently gained significant interest due to their distinctive physical properties. Molybdenum diselenide (MoSe_{2}) is well known as one of transition metal dichalcogenides, which suggests promise as a potential substitute for silicon in stateoftheart transistors, sensors, and photodetectors. A systematic study on temperature dependence of the dielectric function and critical point energies of MoSe_{2} is therefore strongly needed. 

G70.00410: Anisotropic Phononic Bandgap Formation of NanoDicolloid Crystals Hojin Kim, Eric M Furst, George Fytas Selfassembly of colloidal nanoparticles form periodic building blocks and the fabricated crystalline structures exhibit useful photonic and phononic properties because of the periodicity of their structure. Such phononic properties are broadly applicable in technologies such as hypersonic and thermal cloaking materials, heat management systems, and metamaterials. To guide the propagation of acoustic waves to targeted direction, we investigate the potential of selfassembled anisotropic colloidal particles. Colloidal crystals consisted of nanodicolloids are fabricated using directed selfassembly technique under electric field and their hypersonic phonon spectra are measured by Brillouin light scattering (BLS). The anisotropy of dicolloidal particle shape enables crystals to have different periodicity depending on the direction of phonon propagation. We show that the fabricated crystals have anisotropic phononic bandgaps due to both hybridization and Bragg scattering. 

G70.00411: ABSTRACT WITHDRAWN

Follow Us 
Engage
Become an APS Member 
My APS
Renew Membership 
Information for 
About APSThe American Physical Society (APS) is a nonprofit membership organization working to advance the knowledge of physics. 
© 2020 American Physical Society
 All rights reserved  Terms of Use
 Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 207403844
(301) 2093200
Editorial Office
1 Research Road, Ridge, NY 119612701
(631) 5914000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 200452001
(202) 6628700