Astrophysics and Astronomy Commons^™

Exploring Hidden Structure Of The Nearby Universe And The Limits And Capabilities Of Two Neutral Hydrogen Surveys, Monica Sanchez Barrantes

Physics & Astronomy ETDs

We can use the 21 cm neutral hydrogen (HI) emission line to detect galaxies in optically obscured regions, but it is also a faint line that is difficult to detect at higher redshifts. This work presents two HI surveys. The ALFAZOA Survey maps new and predicted large-scale structure across the Galactic plane, and finds a total of 217 completely new galaxies across both of the survey phases. The completeness limits for ALFAZOA Shallow and Deep are presented. Follow-up observations of confused galaxies in ALFAZOA using the VLA determine that confusion in this survey will not cause significant deviations for the …

Understanding Solar Wind Formation By Identifying The Origins Of In Situ Observations, Samantha Wallace

Physics & Astronomy ETDs

Over the past century, significant progress has made on the subjects of two fundamental unresolved questions in Heliophysics, namely 1) how is the solar corona heated to multi-million-degree temperatures, and 2) how is the solar wind formed, from its origin, to its release and acceleration. While the two are in many ways intertwined, this dissertation focuses on the latter. Our current understanding of solar wind formation has developed largely through relating the general origins of the observed solar wind on global spatial scales to the corresponding observed speed at 1 au. However, we are now at a point where long-standing …

Cherenkov Gamma Ray Detectors On High-Energy-Density Systems, Kevin Daniel Meaney

Physics & Astronomy ETDs

High energy density (HED) systems are some of the most extreme environments ever created by mankind. Systems with pressures greater than 1 MBar can only be created by a handful of devices on earth, often utilizing high intensity lasers or pulsed power machines. HED systems offer a view into an extreme form of matter only seen in stellar cores, supernovas and other powerful astrophysical systems. Creating HED systems on Earth offer the possibility, if the physics and technology can be matured, to one day create a fusion power plant. If a system is hot and dense enough, the fusion reaction …

Collective Neutrino Flavor Oscillations In Multiple Dimensions And Scales, Joshua D. Martin

Physics & Astronomy ETDs

Hot and dense astrophysical environments such as the early universe, core collapse novae and binary neutron star mergers generate dense neutrino gases which can sub- sequently have an important effect on processes which occur in these environments. In this thesis we will present the results from several numerical simulations of these gases particularly in cases which are relevant to core collapse supernovae. These simulations employ fewer imposed spatial symmetries than those used in earlier works, and provide insight into behavior which may be expected to occur in three key regions of the explosion. We observe that when the neutrino gas …

On The Complexity Of Boson Sampling Using Atoms In Optical Lattices, Gopikrishnan Muraleedharan

Physics & Astronomy ETDs

The extended Church-Turing thesis says that any computation that can be done by a physically realizable model of computers can be efficiently computed by the simplest model of classical computer, a Turing machine. Since the introduction of the concept of quantum computers, a central goal has been to find instances where the extended Church- Turing thesis fails. In the current noisy intermediate-scale quantum devices era, one looks for such instances that can be simulated on modest devices of small scale in the presence of noise. In this thesis, we work with one such problem, namely the Boson Sampling problem. We …

Investigation Of Membrane Protein Dynamics Using Correlative Single-Particle Tracking And Super-Resolution Microscopy Combined With Bayesian Inference Of Diusion In Arbitrary Landscapes, Hanieh Mazloom Farsibaf

Physics & Astronomy ETDs

Many experiments have shown that the diffusive motion of lipids and membrane proteins are slower on the cell surface than those in artificial lipid bilayers or blebs. One hypothesis that may partially explain this mystery is the effect of the cytoskeleton structures on the protein dynamics. To test this hypothesis, we designed a high-speed single particle tracking microscope and use a hybrid tracking and super-resolution approach on the same cell. We labeled the high-affinity FceRI receptor as a transmembrane protein and GPI-anchored proteins as an example of outer leaflet protein in Rat Basophilic Leukemia (RBL) cells and tracked these membrane …

Direct Observation Of Atomic Exchange During Surface Self-Diffusion, Matthew Aaron Koppa

Physics & Astronomy ETDs

The diffusion of adatoms across the (100) plane of iridium has been previously inferred to occur by an exchange mechanism based on site mapping. This study provides the first direct observation that surface self-diffusion can occur by exchange. Iridium enriched to ≥93% ¹⁹¹Ir was deposited onto an atomically clean and smooth Ir(100) plane as observed in an atom probe field ion microscope. Following thermally activated surface self-diffusion the adatom was field desorbed and mass analyzed. Observation of the ¹⁹³Ir isotope in one-half of the cases demonstrates conclusively that atomic exchange can occur during surface self-diffusion.

Dark Matter Production Beyond The Thermal Wimp Paradigm: An Exploration Of Early Matter Domination Scenarios, Jacek Ksawery Osinski

Physics & Astronomy ETDs

In the standard thermal history of the Universe, the energy density is dominated by radiation throughout the postinflationary era, until matter-radiation equality after big bang nucleosynthesis (BBN). However, we currently do not have any observational probes of the pre-BBN period, and radiation domination (RD) is therefore an assumption. Generic early Universe models predict the presence of additional components in the postinflationary Universe which can lead to periods of nonstandard evolution before the onset of BBN. A prominent example of such a period is a phase of early matter domination (EMD) in which the Universe undergoes matter-dominated expansion for a time, …

Using Natural Phenomena To Study The Ionosphere, Joseph Benjamin Malins

Physics & Astronomy ETDs

This dissertation explores novel techniques for observing the ionosphere using natural signals. The ionosphere is a region of plasma hundreds of kilometers above the Earth that affects communication and remote sensing applications across the world. Traditional techniques for observing the ionosphere involve using man made radio signals, either to reflect the signal at HF frequencies or to pass several signals through the ionosphere and compare the difference the ionosphere makes in the signals. However, such techniques are limited by the ability of equipment to produce these signals and by the numerous laws and regulations governing transmission of signals in the …

Electromagnetic Analysis Of Bidirectional Reflectance From Roughened Surfaces And Applications To Surface Shape Recovery, Julian Antolin Camarena

Physics & Astronomy ETDs

Scattering from randomly rough surfaces is a well-established sub area of electrodynamics. There remains much to be done since each surface and optical processes that may occur in within the scattering medium, and countless other scenarios, is different. There are also illumination models that describe lighting in a scene on the macroscopic scale where geometrical optics can be considered adequate. Of particular interest for us is the intersection of the physical scattering theories and the illumination models. We present two contributions: 1) A minimum of two independent images are needed since any opaque surface can be uniquely specified in terms …

Quantum Algorithms With Applications To Simulating Physical Systems, Anirban Ch Narayan Chowdhury

Physics & Astronomy ETDs

The simulation of quantum physical systems is expected to be an important application for quantum computers. The work presented in this dissertation aims to improve the resource requirements of quantum computers for solving simulation problems, by providing both novel quantum algorithms and improved implementations of existing ones. I present three main results that cover diverse aspects of simulation including equilibrium physics, the preparation of useful quantum states, and simulations based on classical stochastic processes. The results rely on established quantum algorithms and other recent techniques which I review. My first original contribution is a new quantum algorithm to sample from …

Searching For Supermassive Binary Black Holes And Their Gravitational Waves, Karishma Bansal

Physics & Astronomy ETDs

The recent discovery of gravitational waves (GWs) by the LIGO collaboration has opened a new observing window on the universe, but it is limited to the GWs in the frequency range of 10-1000 Hz. The main motivation of this thesis is to consider the possibility of detecting low frequency (nHz) GWs. In the pursuit of these waves, we need to understand their source of origin and build a detector with the required sensitivity. Low-frequency waves are expected as a result of coalescing binary supermassive black holes (SMBBHs). We hope to detect these waves in the near future using pulsar timing …

Studying The Properties Of Sf6 Gas Mixtures For Directional Dark Matter Detection, Randy J. Lafler

Physics & Astronomy ETDs

Although dark matter comprises approximately 85\% of the matter content of the universe, direct detection of dark matter remains elusive. As the available parameter space for dark matter candidates is pushed to lower and lower limits, the demand for larger, more sensitive detectors continues to grow. Although upscaling the detector improves the sensitivity, it greatly increases the cost and complexity of the experiment. Even after a dark matter signal is detected, there remains the possibility that an unknown background mimics the dark matter signal. Consequently, verifying the dark matter origin of a detection signal is an issue for any dark …

Circumstellar Sio Masers In The Bulge Asymmetries And Dynamical Evolution Survey, Michael Cullen Stroh

Physics & Astronomy ETDs

The Bulge Asymmetries and Dynamical Evolution (BAaDE) project aims to explore the complex structure of the inner Galaxy and Galactic Bulge, by using the 43 GHz receivers at the Karl G. Jansky Very Large Array (VLA) and the 86 GHz receivers at the Atacama Large Millimeter/submillimeter Array (ALMA) to observe SiO maser lines in red giant stars. The SiO maser transitions occur at radio frequencies, where extinction is negligible, thus allowing a dense sampling of line-of-sight velocities in the most crowded regions of the Milky Way.

The overall goal of this thesis is to characterize the SiO masers in the …

Studies On The Generation And Detection Of Orbital Angular Momentum Based On Beam-Shaping Techniques, Xijie Luo

Physics & Astronomy ETDs

Light carrying orbital angular momentum (OAM) has many applications ranging from optical manipulation, imaging and remote sensing, and optical communications, and can be used to perform fundamental studies in quantum mechanics and quantum information. Moreover, single photons with high-order OAM allow for increasing the amount of information carried per photon in quantum communication. This thesis describes the study of methods for the preparation and detection of OAM of light in high mode order by utilizing beam shaping techniques using spatial light modulators (SLMs). The quality of the generated high-order OAM mode is limited by optical aberrations which are induced by …

Compact Optical Frequency Standards For Future Applications Beyond The Laboratory, Kyle Martin

Physics & Astronomy ETDs

Atomic clocks provide one of the fundamental building blocks upon which modern telecommunications systems are constructed. Since the invention of the frequency comb in the early 2000s, laboratory frequency standards have quickly outpaced their compact counterparts. Compact clocks, however, have continued to leverage microwave transitions not yet exploring the advantages of an optical atomic clock. With the recent development of robust frequency combs compact optical clocks can now be realized. In this dissertation two atomic species are investigated for a compact atomic frequency standards. Both of these clocks are in different development stages but offer unique advantages. The optical rubidium …

Quantum Algorithms, Architecture, And Error Correction, Ciarán Ryan-Anderson

Physics & Astronomy ETDs

Quantum algorithms have the potential to provide exponential speedups over some of the best known classical algorithms. These speedups may enable quantum devices to solve currently intractable problems such as those in the fields of optimization, material science, chemistry, and biology. Thus, the realization of large-scale, reliable quantum-computers will likely have a significant impact on the world. For this reason, the focus of this dissertation is on the development of quantum-computing applications and robust, scalable quantum-architectures. I begin by presenting an overview of the language of quantum computation. I then, in joint work with Ojas Parekh, analyze the performance of …

Radon Measurement For Neutrinoless Double Beta Decay, Xavier Carlos Quintana

Physics & Astronomy ETDs

This thesis details the design and operation of a high-sensitivity radon detector for use in background radiation characterization and mitigation for the MAJORANA DEMONSTRATOR Neutrinoless Double Beta Decay Experiment and Large Enriched Germanium Experiment for Neutrinoless Double Beta Decay (LEGEND) Collaboration. Understanding and mitigating background radiation is especially important in searches for very rare nuclear processes, which utilize sensitive detectors. One such rare process is the yet-to-be-observed neutrinoless double beta decay. Observation of this process would imply that the neutrino is its own antiparticle, called a Majorana particle, violate lepton number, and provide experimental constraints on the masses and mixing …

Neutrino Flavor Conversions In Dense Media, Lei Ma

Physics & Astronomy ETDs

Neutrinos are abundantly produced in astrophysical environments such as core-collapse supernovae and binary neutron star mergers. Neutrino flavor conversions in the dense media play important roles in the physical and chemical evolutions of the environments. In this dissertation, I study two mechanisms through which neutrinos may change their flavors.

In the first mechanism, neutrinos can experience flavor conversions through interactions with oscillatory perturbations in matter distributions. I show that this mechanism can be understood intuitively as Rabi oscillations. I also derive criteria which can be used to determine whether such parametric resonances exist in a given environment.

In the second …

High-Throughput Automated Multi-Target Super-Resolution Imaging, Farzin Farzam

Physics & Astronomy ETDs

Super-resolution microscopy techniques developed through the past few decades enable us to surpass the classical diffraction limit of light, and thus open new doors to investigate the formerly inaccessible world of nanometer-sized objects. Most importantly, by using super-resolution microscopy, one can visualize sub-cellular structures in the range of 10 to 200 nm. At this range, we can investigate exciting problems in biology and medicine by visualizing protein-protein interactions and spatiotemporal analysis of structures of interest on the surface or inside cells. These techniques (collectively known as nanoscopy) have a high impact on understanding and solving biological questions. This dissertation starts …

Dispersive Quantum Interface With Atoms And Nanophotonic Waveguides, Xiaodong Qi

Physics & Astronomy ETDs

Strong coupling between atoms and light is critical for quantum information processing and precise sensing. A nanophotonic waveguide is a promising platform for realizing an atom-light interface that reaches the strong coupling regime. In this dissertation, we study the dispersive response theory of the nanowaveguide system as the means to create an entangling atom-light interface, with applications to quantum non-demolition (QND) measurement and spin squeezing.

We calculate the dyadic Green's function, which determines the scattering of light by atoms in the presence of a nanowaveguide, and thus the phase shift and polarization rotation induced on the guided light. The Green's …

Novel Nonlinear And Quantum Devices Based On Multimode Optical Fibers, Hamed Pourbeyram

Physics & Astronomy ETDs

In this dissertation, multimode optical fibers (MMFs) have been studied as a robust and practical platform for nonlinear optics and quantum optics applications, where by experimental investigations and theoretical calculations we present the quantum and nonlinear virtue of MMFs as a versatile tool for future applications. Our investigations can be summarized in three parts: At first, we have investigated stimulated Raman scattering (SRS) in a long MMF, where more than 20 orders of cascaded Raman peaks have been generated. Observation of beam clean-up despite the highly multimode nature of the fiber and such strong nonlinear interaction despite the large fiber …

Infrared Properties Of Stars In The Bulge Asymmetries And Dynamical Evolution Survey, Eddie Hilburn

Physics & Astronomy ETDs

The Bulge Asymmetries and Dynamical Evolution (BAaDE) survey is an SiO maser survey of 28,062 infrared-selected evolved stars primarily in the Galactic plane. By cross-matching the BAaDE target sources with nine different infrared catalogs, we have constructed a catalog with wavelength coverage from 0.71 to 80 m. Using this catalog, we fit the data for each source to a model spectral energy distribution (SED) generated with the radiation transport program DUSTY in order to obtain characteristics such as bolometric flux, source effective temperature, and the optical depth of the circumstellar envelope.

The overall goal of the BAaDE survey is to …

Quantum Phase Space Representations And Their Negativities, Ninnat Dangniam

Physics & Astronomy ETDs

A classical simulation scheme of quantum computation given a restricted set of states and measurements may be---occasionally, but only occasionally---interpreted naturally as a statistical simulation of positive quasi-probability distributions on a phase space. In this dissertation, we explore phase space representations for finite-dimensional quantum systems and their negativities beyond the usual analogues of the Wigner function.

The first line of study focuses on a characterization tool for valid quasi-probability distributions of (possibly mixed) quantum states. A quantum generalization of Bochner's theorem from classical probability theory simultaneously characterizes both the set of valid Wigner functions and the subset of positive ones. …

Cavity Enhanced Optical Refrigeration And Spectroscopy, Mohammadreza Ghasemkhani

Physics & Astronomy ETDs

This dissertation is mainly concerned with increasing the pump power absorption in optical refrigeration of solids and photo-acoustic spectroscopy of trace gases using optical cavities. Enhancing the absorption is key to reaching lower temperatures in optical refrigeration and achieving better sensitivity in photo-acoustic spectroscopy.

We have used intra-cavity and coupled-cavity absorption enhancement techniques to increase the absorption in Ytterbium doped Yttrium Lithium Fluoride (Yb³⁺:YLF) crystals. For this purpose, we have developed tunable high-power narrow-linewidth InGaAs/GaAs vertical external-cavity surface-emitting lasers (VECSELs) operating at 1020 nm, the optimal cooling wavelength for Yb:YLF. By inserting a 7% Yb:YLF sample inside the …

Gamma-Ray Metallic Magnetic Calorimeters With Nbta Passive Persistent Switches And Electroformed Au Absorbers, Ruslan Hummatov

Physics & Astronomy ETDs

Metallic Magnetic Calorimeters (MMCs) are low temperature particle detectors which can be used for a wide range of applications including high-resolution γ -ray spectroscopy. High energy resolution in γ -ray spectroscopy is desired for Non Destructive Assay (NDA) of nuclear material and improved measurements of nuclear data. Our group has been developing γ -ray MMCs that should ultimately provide energy resolution more than an order of magnitude better than the benchmark detector technology, high purity germanium detectors (HPGe). Two components of these MMCs have been developed as a part of this dissertation: an on-chip passive superconducting persistent current switch and …

Proposed Method For Measuring The Let Of Radiotherapeutic Particle Beams, Stephen D. Bello

Physics & Astronomy ETDs

The Bragg peak geometry of the depth dose distributions for hadrons allows for precise and effective dose delivery to tumors while sparing neighboring healthy tissue. Further, compared against other forms of radiotherapeutic treatments, such as electron beam therapy (EBT) or photons (x and \(\gamma\)-rays), hadrons create denser ionization events along the particle track, which induces irreparable damage to DNA, and thus are more effective at inactivating cancerous cells. The measurement of radiation's ability to inactivate cellular reproduction is the relative biological effectiveness (RBE). A quality related to the RBE that is a measurable physical property is the linear energy transfer …

Nanowire-Based Light-Emitting Diodes: A New Path Towards High-Speed Visible Light Communication, Mohsen Nami

Physics & Astronomy ETDs

Nano-scale optoelectronic devices have gained significant attention in recent years. Among these devices are semiconductor nanowires, whose dimeters range from 100 to 200 nm. Semiconductor nanowires can be utilized in many different applications including light-emitting diodes and laser diodes. Higher surface to volume ratio makes nanowire-based structures potential candidates for the next generation of photodetectors, sensors, and solar cells. Core-shell light-emitting diodes based on selective-area growth of gallium nitride (GaN) nanowires provide a wide range of advantages. Among these advantages are access to non-polar m-plane sidewalls, higher active region area compared to conventional planar structures, and reduction of threading …

Miniclean Dark Matter Experiment, Juijen Wang

Physics & Astronomy ETDs

Particle Dark Matter is a hypothesis accounting for a number of observed astrophysical phenomena such as the anomalous galactic rotation curves. From these astronomical observation, about 23% of the universe appears to consist of dark matter. Among the possible candidates for dark matter, a plausible one is a Weakly Interacting Massive Particle (WIMP). A particle with the required properties is beyond the standard model of particle physics. The MiniCLEAN experiment is single-phase liquid-argon detector instrumented with 92 photomultiplier tubes placed inside the cryogenic liquid with 4-pi coverage of a 500 kg (150 kg) target (fiducial) mass. For this experiment, PMT …

Molecular Tracers Of Star Formation Feedback In Nearby Galaxies, Mark Gorski

Physics & Astronomy ETDs

The energy and momentum injected into the ISM from stars has a drastic effect on the star formation history of a galaxy. This is called feedback. It is responsible for the inefficient collapse of the ISM into stars. The ``Survey of Water and Ammonia in Nearby Galaxies" (SWAN) is a survey of molecular line tracers in four nearby galaxies. By using molecular tracers of feedback, we provide insights into the star forming ecosystem of the galaxies NGC 253, IC 342, NGC 6946, and NGC 2146. These galaxies were chosen to span an order of magnitude in star formation rate and …