Physics Commons^™

Achieving Laser Wavelength Stability For Use In Neutral Atom Quantum Computing, Jennifer H. Rushing

Physics

Quantum computing may still be decades away from realization but the pieces necessary for the construction of the first quantum chip are beginning to come together. One piece still eluding researchers is the ability to address individual atoms within a scalable quantum chip structure. The resolution to this issue may be found in any one of several promising implementations, including the use of neutral atoms trapped in 2D optical lattices. One method of constructing such lattices, which has been shown to be computationally viable, employs the diffraction pattern just behind a circular aperture. Laser wavelength stability plays a crucial role …

Fast Super-Resolution With Affine Motion Using An Adaptive Wiener Filter And Its Application To Airborne Imaging, Russell C. Hardie, Kenneth J. Barnard, Raúl Ordóñez

Electrical and Computer Engineering Faculty Publications

Fast nonuniform interpolation based super-resolution (SR) has traditionally been limited to applications with translational interframe motion. This is in part because such methods are based on an underlying assumption that the warping and blurring components in the observation model commute. For translational motion this is the case, but it is not true in general. This presents a problem for applications such as airborne imaging where translation may be insufficient. Here we present a new Fourier domain analysis to show that, for many image systems, an affine warping model with limited zoom and shear approximately commutes with the point spread function …

Bi-Stability, Hysteresis, And Memory Of Voltage-Gated Lysenin Channels, Daniel Fologea, Eric Krueger, Yuriy I. Mazur, Christine Stith, Yui Okuyama, Ralph Henry, Greg J. Salamo

Physics Faculty Publications and Presentations

Lysenin, a 297 amino acid pore-forming protein extracted from the coelomic fluid of the earthworm E. foetida, inserts constitutively open large conductance channels in natural and artificial lipid membranes containing sphingomyelin. The inserted channels show voltage regulation and slowly close at positive applied voltages. We report on the consequences of slow voltage-induced gating of lysenin channels inserted into a planar Bilayer Lipid Membrane (BLM), and demonstrate that these pore-forming proteins constitute memory elements that manifest gating bi-stability in response to variable external voltages. The hysteresis in macroscopic currents dynamically changes when the time scale of the voltage variation is …

Characterization Of Enhanced Interferometric Gravitational Wave Detectors And Studies Of Numeric Simulations For Compact-Binary Coalescences, Larne Pekowsky

Physics - Dissertations

Gravitational waves are a consequence of the general theory of relativity. Direct detection of such waves will provide a wealth of information about physics, astronomy, and cosmology. A worldwide effort is currently underway to make the first direct detection of gravitational waves. The global network of detectors includes the Laser Interferometer Gravitational-wave Observatory (LIGO), which recently completed its sixth science run.

A particularly promising source of gravitational waves is a binary system consisting of two neutron stars and/or black holes. As the objects orbit each other they emit gravitational radiation, lose energy, and spiral inwards. This produces a characteristic ``chirp'' …

Searching For Gravitational Waves From Compact Binary Coalescence Using Ligo And Virgo Data, Collin Capano

Physics - Dissertations

This thesis describes current efforts to search for gravitational waves from compact binary coalescences (CBCs) by the LIGO Scientific Collaboration (LSC) and the Virgo Collaboration. We briefly review the physics of gravitational-wave emission and detection, describing how gravitational waves are emitted from "inspiraling" compact stellar mass objects and how the LSC and Virgo try to detect them using interferometers. Next we review the data-analysis principles used to search for potential signals in the detectors' noise. These principles are employed by ``ihope," which is the data-analysis pipeline used to search for CBCs. We describe each step in this pipeline and discuss …

Nonlinear Ordinary Differential Equations In Fluid Dynamics, John D. Ramshaw

Physics Faculty Publications and Presentations

The equivalence between nonlinear ordinary differential equations (ODEs) and linear partial differential equations (PDEs) was recently revisited by Smith, who used the equivalence to transform the ODEs of Newtonian dynamics into equivalent PDEs, from which analytical solutions to several simple dynamical problems were derived. We show how this equivalence can be used to derive a variety of exact solutions to the PDEs describing advection in fluid dynamics in terms of solutions to the equivalent ODEs for the trajectories of Lagrangian fluid particles. The PDEs that we consider describe the time evolution of non-diffusive scalars, conserved densities, and Lagrangian surfaces advected …

Electron Screening And Disorder-Induced Heating In Ultracold Neutral Plasmas, Mary Elizabeth Lyon

Theses and Dissertations

Disorder-induced heating (DIH) is a nonequilibrium, ultrafast relaxation process that occurs when laser-cooled atoms are photoionized to make an ultracold plasma. Its effects dominate the ion motion during the first 100 ns of the plasma evolution. Using tools of atomic physics we study DIH with ns time resolution for different plasma densities and temperatures. By changing the frequency of the laser beam we use to probe the ions, we map out the time evolution of the velocity distribution. We can compare this to a fluorescence simulation in order to more clearly determine the relationship between the fluorescence signal and the …

Electrical Detection Of Mechanical Resonance In Nanotubes And Semiconducting Nanowires, Doyl Dickel

All Dissertations

In recent years, there has been substantial interest in the development of microelectro-mechanical systems (MEMS) and even nanoelectro-mechanical systems (NEMS) for use in a wide variety of applications both as experimental tools (refs) and in a continuing effort to decrease the size and cost and increase the efficiency of electrical components. In particular, cantilevered nanometer beams have been a recent focus due to a number of interesting properties, including enhanced field emission, high tensile strength, and piezoelectric properties. The ability to accurately determine the electrical and mechanical properties of these cantilevers is paramount in assessing their feasibility as MEMS and …

An Embedded Atom Method Investigation Into The Lattice Dynamics Of Metallic Surfaces, Richard B. Wilson

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

The explosion in electronic devices over the last half century is a result of the successful development and application of theories that explain the physical properties of solids. For example, the theory of lattice vibrations developed in the first half of the 20^th century has had a huge impact on our ability to understand and design devices. The idea that atoms vibrate together in grouped vibrational modes, called phonons, has enabled scientists to quantify the impact that atomic motion has on mechanical, thermal, electrical, and optical properties. This has aided the creation of all sorts of useful technology ranging …

Prospects For Determination Of Thermal History After Inflation With Future Gravitational Wave Detectors, Sachiko Kuroyanagi, Kazunori Nakayama, Shun Saito

Physics Faculty Research & Creative Works

Thermal history of the Universe between inflation and big-bang nucleosynthesis has not yet been revealed observationally. It will be probed by the detection of primordial gravitational waves generated during inflation, which contain information on the reheating temperature as well as the equation of state of the Universe after inflation. Based on the Fisher information formalism, we examine how accurately the tensor-to-scalar ratio and reheating temperature after inflation can be simultaneously determined with space-based gravitational wave detectors such as the DECI-hertz Interferometer Gravitational-wave Observatory and the Big-Bang Observer. We show that the reheating temperature is best determined if it is around …

Thermal Correction To The Molar Polarizability Of A Boltzmann Gas, Ulrich D. Jentschura, Mariusz Puchalski, Peter J. Mohr

Physics Faculty Research & Creative Works

Metrology in atomic physics has been crucial for a number of advanced determinations of fundamental constants. In addition to very precise frequency measurements, the molar polarizability of an atomic gas has recently also been measured very accurately. Part of the motivation for the measurements is due to ongoing efforts to redefine the International System of Units (SI), for which an accurate value of the Boltzmann constant is needed. Here we calculate the dominant shift of the molar polarizability in an atomic gas due to thermal effects. It is given by the relativistic correction to the dipole interaction, which emerges when …

Highly Resistive And Ultrafast Fe‐Ion Implanted Ingaas For The Applications Of Thz Photomixer And Photoconductive Switch, J. H. Shin, K. H. Park, N. Kim, C. W. Lee, Eunsup Daniel Shim, Y. C. Kim, D. S. Yee, J. O. Kim, S. J. Lee, S. K. Noh

WCBT Faculty Publications

We develop highly‐resistive (i.e. low‐carrier‐density) and ultrafast Fe‐ion implanted InGaAs layers for the applications of THz photomixer and photoconductive switch. The measured Hall mobility, sheet resistance, carrier density, and carrier lifetime of the optimized 1.2‐μm‐thick Fe‐implanted InGaAs layer are 3.4×102 cm2/Vs, 0.24 MΩ, 6.5×1014 cm−3, and 0.13ps, respectively.

Prototype Automated Flow-Through Sensor For Measuring Waterborne Microbial Concentrations Using Bulk Fluorescence, Susan M. Savill

Graduate Masters Theses

Timely and inexpensive monitoring of microbial ecology in the world's water supplies is crucial to the study of environmental and human impact on water quality and the prevention of disease outbreaks. Current technology is lacking in its ability to accurately measure and predict the presence of possible disease pathogens in a timely and cost effective manner. This paper describes the construction and initial testing of an automated prototype water sensor intended to detect fluctuations in microbial density in real-time by using bulk fluorescence of SYBR Gold stained bacteria. The sensor is comprised of off-the-shelf hardware and an in-house designed and …

Interacting Stochastic Processes: From Viciousness To Caging To Force Chains, Shiliyang Xu

Physics - Dissertations

This thesis documents a quest to develop and study several novel interacting stochastic processes. As for the first example, we generalize a system of vicious random walkers in which the only interaction between any two random walkers is that when they intersect, both walkers are annihilated. We define a system of N vicious accelerating walkers with each walker undergoing random acceleration and compute the survival probability distribution for this system. We also define and study a system of N vicious Levy flights in which any two Levy flights crossing one another annihilate each other. The average mean-squared displacement of a …

Sufficient Conditions For Uniqueness Of The Weak Value, Justin Dressel, Andrew N. Jordan

Mathematics, Physics, and Computer Science Faculty Articles and Research

We review and clarify the sufficient conditions for uniquely defining the generalized weak value as the weak limit of a conditioned average using the contextual values formalism introduced in Dressel, Agarwal and Jordan (2010 Phys. Rev. Lett. 104 240401). We also respond to criticism of our work by Parrott (arXiv:1105.4188v1) concerning a proposed counter-example to the uniqueness of the definition of the generalized weak value. The counter-example does not satisfy our prescription in the case of an underspecified measurement context. We show that when the contextual values formalism is properly applied to this example, a natural interpretation of the …

Fabrication Of All-Inorganic Nanocrystal Solids Through Matrix Encapsulation Of Nanocrystal Arrays, Erich Kinder, Pavel Moroz, Geoffrey Diederich, Alexa Johnson, Maria Kirsanova, Alexander Nemchinov, Timothy O’Connor, Dan Roth, Mikhail Zamkov

Physics and Astronomy Faculty Publications

A general strategy for low-temperature processing of colloidal nanocrystals into all-inorganic films is reported. The present methodology goes beyond the traditional ligand-interlinking scheme and relies on encapsulation of morphologically defined nanocrystal arrays into a matrix of a wide-band gap semiconductor, which preserves optoelectronic properties of individual nanoparticles while rendering the nanocrystal film photoconductive. Fabricated solids exhibit excellent thermal stability, which is attributed to the heteroepitaxial structure of nanocrystal matrix interfaces, and show compelling light-harvesting performance in prototype solar cells.

Spectroscopic Studies Of Melamine At High Pressure, Martin Donald Galley

UNLV Theses, Dissertations, Professional Papers, and Capstones

We have performed mid- and far- Infra Red (IR) absorption, Raman spectroscopy, and angular dispersive x-ray diffraction (XRD) studies on melamine under high pressure and room temperature. We have verified the presence of two prior reported phase transitions, the first between 1-2 GPa, and the second between 7-9 GPa. We have also found evidence of a third unreported phase transition between 14-16 GPa, during which, there was a sudden disappearance of all low energy peaks (^-1 ) in both the Raman and IR spectra. The far-IR peak movement experiences a discontinuity as the rate of peak movement suddenly changes. …

The Relation Between Black Hole Mass And Host Spheroid Stellar Mass Out To Z~2, Vardha N. Bennert, Matthew A. Auger, Tommaso Treu, Jong-Hak Woo, Matthew A. Malkan

Physics

We combine Hubble Space Telescope images from the Great Observatories Origins Deep Survey with archival Very Large Telescope and Keck spectra of a sample of 11 X-ray-selected broad-line active galactic nuclei in the redshift range 1 < z < 2 to study the black-hole-mass-stellar-mass relation out to a look-back time of 10 Gyr. Stellar masses of the spheroidal component (M _sph, ) are derived from multi-filter surface photometry. Black hole masses (M _BH) are estimated from the width of the broad Mg II emission line and the 3000 Å nuclear luminosity. Comparing with a uniformly measured local sample and taking into account selection effects, we find evolution in the form M _BH/M _sph, (1 + z)^{1.96 …}

Quantum Many-Body Calculation Of Mixed-Parity Pairing In The Sr2ruo4 Superconductor Induced By Spin-Orbit Coupling, J. J. Deisz, Tim Kidd

Faculty Work

The unusual superconducting state in Sr₂RuO₄ has long been viewed as being analogous to a superfluid state in liquid ³He. Nevertheless, calculations based on this odd-parity state are presently unable to completely reconcile the properties of Sr₂RuO₄. Using a self-consistent quantum many-body scheme that employs realistic parameters, we are able to model several signature properties of the normal and superconducting states of Sr₂RuO₄. We find that the dominant component of the model superconducting state is of even parity and closely related to superconducting state for the high-T_{c …}

Mathematical Modeling Of Peristaltic Flow Of Chyme In Small Intestine, Daniel N. Riahi, Ranadhir Roy

Applications and Applied Mathematics: An International Journal (AAM)

Mathematical models based on axisymmetric Newtonian incompressible fluid flow are studied for the peristaltic flow of chyme in the small intestines, which is an axisymmetric cylindrical tube. The flow is modeled more realistically modeled by assuming that the peristaltic rush wave is a non-periodic mode composed of two sinusoidal waves of different wavelengths, which propagate at the same speed along the outer boundary of the tube. Both cases of flow in a tube and in an annulus that are modeled and investigated in the present paper correspond respectively to the cases of flow of chyme in the small intestine in …

The Singular Perturbation In The Analysis Of Mode I Fracture Based Upon A New Multiscale Theory, Kai-Bin Fu

Applications and Applied Mathematics: An International Journal (AAM)

A theory of fracture is presented that is based upon an extension of continuum mechanics to the nanoscale fracture through the incorporation of long-range intermolecular forces which correct bulk material descriptions near interfaces. To be consistent with the literature, constant surface energies are assigned to interfaces. In the analysis of mode I fracture for quasi-brittle material, it is observed that the incorporation of these long-range intermolecular forces predicts sharp fracture tip rather than blunt and avoids stress singularity. The details of the singular perturbation employed in this analysis are also presented.

The Power Series Solution Of Fingering Phenomenon Arising In Fluid Flow Through Homogeneous Porous Media, Kinjal Patel, M. N. Mehta, Twinkle R. Patel

Applications and Applied Mathematics: An International Journal (AAM)

The present paper deals with the approximate solution of the fingering phenomenon occurring when water is pushed into oil in homogeneous porous media with capillary mean pressure. The phenomenon is formulated mathematically as a water-oil double phase flow problem. The solution of the nonlinear partial differential equation of fingering phenomenon has been discussed in terms of the power series using appropriate boundary conditions for any timeT>0 . The solution is in ascending power series which represents saturation of injected fluid in fingering phenomenon & its graphical and numerical presentation is given in MATLAB coding.

Reflection Of Waves In Transversely Isotropic Thermoelastic Solid, Raj R. Gupta

Applications and Applied Mathematics: An International Journal (AAM)

The main objective of the present paper is to study the propagation of waves in the transversely isotropic medium in the context of thermoelasticity with GN theory of type-II and III. By imposing the boundary conditions on the components of displacement, stresses and temperature distribution, wave equation have been solved. Numerically simulated results have been plotted graphically with respect to frequency to evince the effect of anisotropy. Keywords: Thermoelasticity, transversely isotropic, reflection, plane wave AMS 2010 No.: 74JXX, 74F, 74B, 80A. 1. Introduction In last three decades, non-classical theories involving finite speed of heat transportation in elastic solids have been …

Stability Of Stratified Couple-Stress Dusty Fluid In The Presence Of Magnetic Field Through Porous Medium, Vivek Kumar

Applications and Applied Mathematics: An International Journal (AAM)

The combined effect of magnetic field and dust particles on the stability of a stratified couplestress fluid through a porous medium is considered. For stable stratification, the system is found to be stable for disturbances of all wave numbers. The magnetic field succeeds in stabilizing the potentially unstable stratifications for a certain wave-number range which were unstable in the absence of the magnetic field. Discussions of oscillatory and non-oscillatory modes are also made.

A New Algorithm For Solving Shortest Path Problem On A Network With Imprecise Edge Weight, Amit Kumar, Manjot Kumar

Applications and Applied Mathematics: An International Journal (AAM)

Nayeem and Pal (Shortest path problem on a network with imprecise edge weight, Fuzzy Optimization and Decision Making 4, 293-312, 2005) proposed a new algorithm for solving shortest path problem on a network with imprecise edge weight. In this paper the shortcomings of the existing algorithm, (Nayeem and Pal, 2005) are pointed out and to overcome these shortcomings a new algorithm is proposed. To show the advantages of the proposed algorithm over existing algorithm the numerical examples presented in (Nayeem and Pal, 2005) are solved using the proposed algorithm and obtained results are discussed.

Quantitative Comparison Of Late Effects Following Photon Versus Proton External-Beam Radiation Therapies: To Ward An Evidence-Based Approach To Selecting A Treatment Modality, Rui Zhang

Dissertations and Theses (Open Access)

Radiation therapy has been used as an effective treatment for malignancies in pediatric patients. However, in many cases, the side effects of radiation diminish these patients’ quality of life. In order to develop strategies to minimize radiogenic complications, one must first quantitatively estimate pediatric patients’ relative risk for radiogenic late effects, which has not become feasible till recently because of the calculational complexity. The goals of this work were to calculate the dose delivered to tissues and organs in pediatric patients during contemporary photon and proton radiotherapies; to estimate the corresponding risk of radiogenic second cancer and cardiac toxicity based …

First-Principles Studies On Physical And Chemical Properties Of Nanostructures, Menghao Wu

Department of Physics and Astronomy: Dissertations, Theses, and Student Research

The physical and chemical properties of decorated graphene and graphene ribbons, single-layer III-V systems, three-dimensional carbon and BN foam, and transition-metal-molecular sandwich nanowires have been investigated by first-principle calculations and their potential applications have been predicted. First, it is shown that zigzag graphene nanoribbons (ZGNRs) can be converted into half metal when their edges are decorated by some chemical functional groups, and the half-metalicity is induced by chemical potential difference between two edges when one edge is decorated by electron-donating group like –OH and the other edge is decorated by electron-accepting group like –F, -NH₂, -N(CH₃) …

Evaluation Of Deformable Image Registration For Improved 4d Ct-Derived Ventilation For Image Guided Radiotherapy, Richard Castillo

Dissertations and Theses (Open Access)

Recent treatment planning studies have demonstrated the use of physiologic images in radiation therapy treatment planning to identify regions for functional avoidance. This image-guided radiotherapy (IGRT) strategy may reduce the injury and/or functional loss following thoracic radiotherapy. 4D computed tomography (CT), developed for radiotherapy treatment planning, is a relatively new imaging technique that allows the acquisition of a time-varying sequence of 3D CT images of the patient's lungs through the respiratory cycle. Guerrero et al. developed a method to calculate ventilation imaging from 4D CT, which is potentially better suited and more broadly available for IGRT than the current standard …

Peristaltic Induced Flow Of A Two-Layered Suspension In Non-Uniform Channel, Amit Medhavi, Dharmendra Singh, Ajay S. Yadav, Ramesh S. Gautam

Applications and Applied Mathematics: An International Journal (AAM)

Peristaltic transport of a two-layered particulate suspension in a non-uniform channel has been investigated. The coupled differential equations for both the fluid and the particle phases in the central as well as in the peripheral layers have been solved and the expression for the flow rate, the pressure rise and the friction force has been derived. The results obtained are discussed both qualitatively and quantitatively in brief. The significance of the particle concentration as well as the peripheral layer has been well explained.

Morphological Features Of Elongated-Anisotropic Magnetosome Crystals In Magnetotactic Bacteria Of The Nitrospirae Phylum And The Deltaproteobacteria Class, Christopher T. Lefèvre, Mihály Pósfai, Fernanda Abreu, Ulysses Lins, Richard B. Frankel, Dennis A. Bazlinski

Physics

High resolution transmission electron microscopy was used to study the crystallographic habits of the elongated magnetite crystals, variously described as bullet-, tooth- or arrowhead-shaped, in two recently described, uncultured, magnetotactic bacteria belonging to the Nitrospirae phylum designated Candidatus Magnetoovum mohavensis strain LO-1, and Candidatus Thermomagnetovibrio paiutensis strain HSMV-1; and a cultured sulfate-reducing magnetotactic bacterium of the Deltaproteobacteria class of the Proteobacteria phylum designated strain AV-1. The elongation axes of the magnetosomes do not coincide with the easy magnetization axis (which is [111]) but they are parallel to [100] in LO-1 and AV-1 and parallel to [110] in HSMV-1. In all …