Physics Commons^™

Theoretical Framework Of Exchange Coupled Tripartite Spin Systems With Magnetic Anisotropy And Predictions Of Spin And Electronic Transport Properties For Their Use In Quantum Architectures, Eric Switzer

Electronic Theses and Dissertations, 2020-

There has been significant interest in spin systems involving two or more coupled spins as a single logical qubit, particularly for scalable quantum computing architectures. Recent realizations include the so-called singlet-triplet qubits and coupled magnetic molecules. An important class of coupled-spin systems, the three-spin paradigm for spin greater than 1/2, has not yet been fully realized in scalable qubit architectures. In this thesis, I develop the theoretical framework to investigate a class of tripartite spin models for realistic systems. First, I model a spin 1/2 particle (e.g., an electron) and two spin 1 particles (in a dimer arrangement) coupled with …

Theoretical Analysis Of Charge Conduction And Rectification In Self-Assembled-Monolayers In Molecular Junctions, Francis Adoah

Electronic Theses and Dissertations, 2020-

As electrical devices shrink to the atomic scale, it is expected that Moore's law will soon be obsolete for semiconductor devices. In 1974, Avriam and Ratner predicted that organic devices could replace semiconductor technology, leading to extensive research on molecular-based organic devices. This dissertation delves into the theoretical frameworks used to examine the transport in molecular junctions and aims to enhance our comprehension of charge transport and conduction properties. The studies presented in this thesis illustrates that a molecule's alteration by just a single atom can change it from an insulator to a conductor, and also that, by fine-tuning the …

Due Tomorrow, Do Tomorrow: Measuring And Reducing Procrastination Behavior Among Introductory Physics Students In An Online Environment, Zachary Felker

Electronic Theses and Dissertations, 2020-

This work is focused on the measurement and prevention of procrastination behavior among college level introductory physics students completing online assignments in the form of mastery-based online learning modules. The research is conducted in two studies. The first study evaluates the effectiveness of offering students the opportunity to earn a small amount of extra credit for completing portions of their homework early. Unsupervised machine learning is used to identify an optimum cutoff duration which differentiates taking a short break during a continuous study session from a long break between two different study sessions. Using this cutoff, the study shows that …

Reflective Planar Optics With Cholesteric Liquid Crystal For Near-Eye Displays, Yannanqi Li

Electronic Theses and Dissertations, 2020-

Display market has undergone dramatic changes as the near eye displays (NED) are gaining increasing attention because they offer a deeper level of human-computer interaction with the advancement of electronic devices and computer sciences. The NEDs can be presented in two ways: virtual reality (VR) and augmented reality (AR). The former is completely immersive while the latter combines the digital information with the surrounding scenes. Although several VR headsets have been commercialized for consumers and AR products for prosumers because of their high cost, but there is still a long way to go to satisfy the strict requirements of human …

Integrated Frequency Combs For Applications In Optical Communications & Microwave Photonics, Chinmay Shirpurkar

Electronic Theses and Dissertations, 2020-

This dissertation reviews the advancements made in chip-scale optical frequency combs and their applications towards optical communications and optical to RF links. We review different chip-scale comb sources and in particular, chip-scale Kerr microresonator frequency combs. Then, we establish the theoretical background in nonlinear optics which allows the formation and stabilization of Kerr solitons in nonlinear cavities. We also discuss the concept of optical injection locking and in particular, multi-tone injection locking which precedes the idea of regenerative harmonic injection locking. We then go on to show the experimental work involved in soliton generation and characterization. We show efforts towards …

High-Dynamic-Range And High-Efficiency Near-Eye Display Systems, En-Lin Hsiang

Electronic Theses and Dissertations, 2020-

Near-eye display systems, which project digital information directly into the human visual system, are expected to revolutionize the interface between digital information and physical world. However, the image quality of most near-eye displays is still far inferior to that of direct-view displays. Both light engine and imaging optics of near-eye display systems play important roles to the degraded image quality. In addition, near-eye displays also suffer from a relatively low optical efficiency, which severely limits the device operation time. Such an efficiency loss originates from both light engines and projection processes. This dissertation is devoted to addressing these two critical …

Multi-Kilowatt Fiber Laser Amplifiers And Hollow-Core Delivery Fibers, Matthew Cooper

Graduate Thesis and Dissertation 2023-2024

High-power fiber lasers have emerged as a cornerstone in the realm of laser technology. Characterized by their exceptional efficiency, ruggedness, and versatility, fiber lasers are experiencing widespread use in manufacturing, medical, defense, science, and in long range sensing. Unfortunately, high-power applications require strict spatial and spectral performance characteristics to be maintained, which has yet to be perfected.

This dissertation discusses the power scaling of ytterbium-doped fiber laser amplifiers, presenting three significant advancements. First, a novel photonic lantern-based method is introduced for real-time monitoring of laser beam modal content and beam quality. Initial tests highlight the photonic lantern's efficiency in predicting …

Low Energy Photon Detection, Tianyi Guo

Graduate Thesis and Dissertation 2023-2024

Detecting long wave infrared (LWIR) light at room temperature has posed a persistent challenge due to the low energy of photons. The pursuit of an affordable, high-performance LWIR camera capable of room temperature detection has spanned several decades. In the realm of contemporary LWIR detectors, they can be broadly classified into two categories: cooled and uncooled detectors. Cooled detectors, such as MCT detectors, excel in terms of high detectivity and fast response times. However, their reliance on cryogenic cooling significantly escalates their cost and restricts their practical applications. In contrast, uncooled detectors, exemplified by microbolometers, are capable of functioning at …

A Theoretical Study Of Elementary Processes In Interstellar Plasma, Joshua Forer

Graduate Thesis and Dissertation 2023-2024

Interstellar plasma — interstellar clouds in particular — play an important role in determining the structure and evolution of galaxies. Understanding the time evolution of such plasmas requires knowledge of the chemical processes that drive their dynamics. Two processes are studied in this dissertation: radiative electron attachment (REA) via dipole-bound states (DBSs) and dissociative recombination (DR). Of the several hundred molecules detected in the interstellar medium, only eight anions have been detected: CN-, C3N-, C5N-, C7N-, C4H-, C6H-, C8H-, and C10H-. Their production mechanism is not well known; REA was suggested as a possible formation pathway, but previous theoretical studies …

Optical Characterization Of Liquids: Refractive Index And Raman Gain Coefficient Measurements, Cesar A. Lopez-Zelaya

Graduate Thesis and Dissertation 2023-2024

Novel technologies capable of generating wavelengths not accessible with typical laser gain media have been among the primary drivers of the field of nonlinear optics. Here, we are interested in the linear and nonlinear properties of liquids beyond the visible spectrum, motivated in part by their use as core materials in optical fibers. Given their dispersion, nonlinearities, transparency, and ability to be mixed, liquids show potential for exploiting in-fiber nonlinear phenomena for developing the new generation of low cost, size, weight, and power wavelength-agile fiber-laser sources. For the design, modeling, and experimental realization of these liquid-core fiber laser sources, proper …

Dna Capture And Translocation Through Nanopore, Swarnadeep Seth

Graduate Thesis and Dissertation 2023-2024

This thesis investigates DNA dynamics and translocation through nanopores using Brownian dynamics (BD) simulations, offering insights into sequencing technologies, DNA marker detection, and accurate barcoding utilizing solid-state nanopore platforms. First, we in silico study the intricate process of capture and translocation in a single nanopore. Our simulation reveals a high probability of hairpin loop formation during the capture process. However, attaching a charged tag to one end of DNA improves multi-scan rates and enhances unidirectional translocations. We use modulating voltage biases to multi-scan a lambda-phage dsDNA with oligonucleotide flap markers (tags) through a single and double nanopore system. Our study …

Compact And High Optical Efficiency Near-Eye Displays With Liquid Crystal Flat Optics, Junyu Zou

Electronic Theses and Dissertations, 2020-

Since the concepts of augmented reality (AR) and virtual reality (VR) were introduced, they have attracted people's attention worldwide, both in the industry and research areas. As the most promising hardware architecture that can bring AR/VR into daily life, near eye displays (NEDs) have been studied and investigated heavily over the past half-century, especially the concept of "Metaverse" introduced by some top companies in recent years. However, the form factor and optical efficiency are two major bottlenecks for the current NEDs before they can become the major platform. Liquid crystal (LC) flat optics have several advantages, including compact, high diffraction …

Understanding The Pressure-Sinkage Relationship For Simulated Lunar Regolith And Implications On Bearing Capacity And Trafficability, Catherine A. Millwater

Honors Undergraduate Theses

The intent of this thesis is to explore the pressure-sinkage relationship for simulated lunar regolith (simulant). The simulants used in this experiment emulate the lunar highlands (LHS-1) and the lunar mare (LMS-1). The ultimate ability of a terrain or regolith to support a load without shear failure is vital to the planning and construction of permanent infrastructure. This relationship can be measured by applying a normal load to the regolith until shear failure, from which allowable and ultimate bearing capacity can be deduced. An understanding of the pressure-sinkage of lighter loads on the higher ‘fluffy' layer of regolith is of …

Observation Of Gapless Nodal-Lines In A Rare-Earth-Based Compound, Robert Smith

Honors Undergraduate Theses

This thesis aims to contribute to the understanding of quantum materials by employing a combination of experimental techniques, such as angle-resolved photoemission spectroscopy and magnetic and transport measurements. Further collaborative support in the form of first-principles calculations is included and discussed in tandem. In this thesis, a lanthanide-based semimetal of the ZrSiS type, is investigated. Multiple nodal lines which remain gapless are observed along the X-R direction of the Brillouin zone. We also present a nodal line that is observed further below the Fermi level and aligned in the G-M direction; this nodal line appears to be sensitive to light …