Bulletin of the American Physical Society
20th Annual Meeting of the APS Northwest Section
Volume 64, Number 9
Thursday–Saturday, May 16–18, 2019; Western Washington University, Bellingham, Washington
Session D2: Condensed Matter II |
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Chair: John Neumeier, Montana State University Room: Viking Union 567 |
Friday, May 17, 2019 3:30PM - 4:00PM |
D2.00001: Optimal control for quantum information processing and quantum simulations Invited Speaker: Armin Rahmani Adiabatic evolution is central to many near-term approaches to information processing and quantum-assisted simulations (e.g., quantum annealing for computational optimization and braiding of non-Abelian anyons for topological quantum computing). However, slower processes needed for adiabaticity require longer time scales, over which the system may decohere or suffer noise-induced antiadiabaticity. Fast optimally controlled nonadiabatic dynamics, based on the Pontryagin’s minimum principle, can help overcome these difficulties. Here, we discuss novel applications of optimal control to variational quantum algorithms, quantum optimization algorithms, simulation of many-body ground states, and braiding noisy Majorana zero modes. [Preview Abstract] |
Friday, May 17, 2019 4:00PM - 4:12PM |
D2.00002: Novel Application of a Gaussian Model of the Band-Edge in the Study of Defect Dynamics in ZnO Thin Film Amrah Canul, Dinesh Thapa, Jeffrey Lapp, Jesse Huso, Leah Bergman The Urbach model and band-edge analysis in UV-Vis absorption spectra has been at the forefront of investigations into the defect physics of ZnO thin films and many other materials. A unique combination of differential and deconvolution analysis shows that the basic Urbach model is not sufficient to accurately model the differential band-edge in ZnO thin film. To do so, we employ the small addition of a Gaussian term to the basic Urbach model. With this Gaussian model, we extract directly from the spectra parameters such as the unperturbed band-edge, $E_{o}$, and the spread in bandgap energies due to the defect distribution, $w$. We provide substantial experimental support for defining the physical parameters as such, including independent XRD studies. Furthermore, we illustrate an application of this model and analytical approach in the study of defect dynamics in ZnO. Through a series of annealing treatments we show strong evidence for activation of grain growth at 400 C. Finally, we show the distinct separation of ZnO thin film thermo-optical properties, band-edge redshifting and broadening into an amorphous and a crystalline regime. [Preview Abstract] |
Friday, May 17, 2019 4:12PM - 4:24PM |
D2.00003: Mg$_{\mathrm{x}}$Zn$_{\mathrm{1-x}}$O metastable alloy films: growth and properties. Dinesh Thapa, Jesse Huso, Jeffrey Lapp, Amrah Canul, Matthew McCluskey, Leah Bergman MgxZn1-xO, where x is the composition, is a vital semiconductor alloy system that can span bandgaps in a deep UV range of 3.3 to 7.5 eV. The alloy films were grown far from thermodynamic equilibrium condition in a metastable state, thus knowledge of their thermal stability is a key issue for applications at elevated temperature. The thermal stability of the films was studied via post-growth annealing. Structural and optical properties of both as-grown and annealed films were studied using XRD and transmission spectroscopy. The as-grown films were found to exhibit a single wurtzite phase up to Mg composition x$=$0.57 and single cubic phase for x $\ge $ 0.75. However, the film for x $=$ 0.68 was found to be in the mixed phase. The existence of single wurtzite phase as-grown films with high Mg composition is discussed in terms of the low growth temperature and small lattice constant of the wurtzite relative to the cubic structure. The annealing studies showed that single phase wurtzite films were thermally stable up to x $=$ 0.25, while the annealed cubic films were stable for x $\ge $ 0.83. [Preview Abstract] |
Friday, May 17, 2019 4:24PM - 4:36PM |
D2.00004: An upper bound to gas delivery via pressure-swing adsorption in nanoporous materials Jordan Pommerenck, Cory Simon, David Roundy The transportation sector accounts for 38\% of US energy-related carbon dioxide emissions and generates toxic air pollution (particulate matter, ozone, NO$_x$, SO$_x$, carbon monoxide, volatile organic compounds) . Alternative transportation fuels, such as natural gas or hydrogen, are therefore critical to mitigate climate change and improve air quality. Both natural gas and hydrogen (gas) possess a very low volumetric energy density compared to (liquid) gasoline. Consequently, under storage space constraints in passenger vehicles, they must be densified such as through physical adsorption on nanoporous materials in order to drive a reasonable distance on a full tank of fuel. The US Department of Energy (DOE) set storage targets for adsorbed natural gas and hydrogen onboard light vehicles. To assess the feasibility of these targets, we provide a theoretical upper bound on the density of natural gas and hydrogen that can be stored in and delivered by nanoporous materials via a pressure swing. We conclude that, while the DOE storage targets are theoretically possible, the material would require a void fraction that is outside the range of void fractions in known materials exhibiting sufficient interactions with the gas. [Preview Abstract] |
Friday, May 17, 2019 4:36PM - 4:48PM |
D2.00005: Retardation of the field in a weakly compressible fluid Ildoo Kim We discuss the retardation of the velocity field in a weakly two-dimensional fluid channel, in specific the flowing soap film channel. It is previously known that in this system the velocity field is strongly correlated to the thickness field and that the thickness field propagate at the Marangoni wave speed. We produce simple vortex streets in flowing soap films to show that the vortex structure changes depending on the speed of the mean flow $u$ and the speed of Marangoni wave $v_M$. The spacing ratio of the vortex street decreases as $u/v_M\rightarrow1$, and the dependence is characterized by the factor $1/(1+u/v_M)$. [Preview Abstract] |
Friday, May 17, 2019 4:48PM - 5:00PM |
D2.00006: Development of a Characterization Method for Determining Material Behavior of Mechanically Tested Additive Manufacturing Material by Time-Resolved Infrared Radiometry Md Salah uddin, Brahmananda Pramanik Additive manufacturing (AM) is a widely used manufacturing process for producing complex geometric functional parts. It is a rapid prototyping technology that fabricates three-dimensional object under computer control by joining material layer-by-layer. AM method is widely applied in aerospace, automotive, and medical industries. Time-resolved infrared radiometry (TRIR) is a non-destructive testing method for investigating material. Recently, the application of TRIR method to AM material receives attention to many researchers. We applied the TRIR method for characterizing mechanically tested AM materials. We developed a model for determining material parameters for mechanically deformed specimens for characterizing the time-temperature relationship. [Preview Abstract] |
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