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Weak Measurement And Quantum Smoothing Of A Superconducting Qubit, Dian Tan

Arts & Sciences Electronic Theses and Dissertations

In quantum mechanics, the measurement outcome of an observable in a quantum system is intrinsically random, yielding a probability distribution. The state of the quantum system can be described by a density matrix (t), which depends on the information accumulated until time t, and represents our knowledge about the system. The density matrix (t) gives probabilities for the outcomes of measurements at time t. Further probing of the quantum system allows us to refine our prediction in hindsight. In this thesis, we experimentally examine a quantum smoothing theory in a superconducting qubit by introducing an auxiliary matrix E(t) which is …

Sequence Determinants Of The Individual And Collective Behaviour Of Intrinsically Disordered Proteins, Alexander S. Holehouse

Arts & Sciences Electronic Theses and Dissertations

Intrinsically disordered proteins and protein regions (IDPs) represent around thirty percent of the eukaryotic proteome. IDPs do not fold into a set three dimensional structure, but instead exist in an ensemble of inter-converting states. Despite being disordered, IDPs are decidedly not random; well-defined - albeit transient - local and long-range interactions give rise to an ensemble with distinct statistical biases over many length-scales. Among a variety of cellular roles, IDPs drive and modulate the formation of phase separated intracellular condensates, non-stoichiometric assemblies of protein and nucleic acid that serve many functions. In this work, we have explored how the amino …

Determining The Molecular Mechanisms Of Huntington’S Disease Through Multi-Scale Modeling, Kiersten Ruff

Arts & Sciences Electronic Theses and Dissertations

Huntington’s disease (HD) is associated with a mutational CAG repeat expansion within exon 1 of the huntingtin (Htt) gene. Post-transcriptional processing leads to the generation of N-terminal Htt protein fragments (Htt-NTFs), including those that encompass exon 1 (Httex1). Within Httex1, the CAG-repeat encoded polyglutamine (polyQ) tract is flanked N-terminally by a 17-residue amphipathic stretch (N17) and C-terminally by a 50-residue proline rich (PR) domain. Htt-NTFs, including Httex1, are among the smallest fragments that recapitulate HD pathology in mouse models. However, the direct link between Htt-NTFs with polyQ expansions and neurodegeneration that leads to HD remains unresolved. Despite being a monogenic …

Topics In Qcd At Nonzero Temperature And Density, Kamal Pangeni

Arts & Sciences Electronic Theses and Dissertations

Understanding the behavior of matter at ultra-high density such as neutron stars require the knowledge of ground state properties of Quantum chromodynamics (QCD) at finite chemical potential. However, this task has turned out to be very difficult because of two main reasons: 1) QCD may still be strongly coupled at those regimes making perturbative calculations unreliable and 2) QCD at finite density suffers from the sign problem that makes the use of lattice simulation problematic and it even affects phenomenological models. In the first part of this thesis, we show that the sign problem in analytical calculations of finite density …

Stellar And Interstellar Origins Of Meteoritic Nanodiamonds, Josiah Lewis

Arts & Sciences Electronic Theses and Dissertations

In 1987 presolar grains were first isolated from meteorites, opening up a new line of data about the stars that produced them. Based on anomalies in isotopic ratios, identification and classification of presolar grains has borne great fruit in understanding nucleosynthesis, stellar evolution, and mass loss from the stellar objects in which these grains originated: primarily, but not exclusively, supernovae and asymptotic giant branch stars.Meteoritic nanodiamonds were the first type of presolar grain identified, but more than three decades later, their origins remain unclear. Anomalies in the ratios of Xe isotopes carried by the nanodiamonds suggest the nanodiamonds formed from …

Nuclear Spin Alignment In Optically Pumped Semiconductors, Matthew M. Willmering

Arts & Sciences Electronic Theses and Dissertations

Nuclear magnetic resonance (NMR) has shown its ability to be a very informative analytical technique due to the ability to measure very small changes in the energy splittings due to the nuclei’s local environment. However, this ability is hindered by the low sensitivity of the experiment. Many methods have been postulated and implemented to enhance the sensitivity of NMR experiments; one of which is optically pumped NMR (OPNMR). In this dissertation, the usefulness and potential applications of OPNMR are presented. First, a doubly resonant OPNMR probe was fabricated in order to complete more advanced NMR techniques while optically pumping the …

Supercooled: An Equilibrium, Melting-Based, Energy Distribution Approach For Describing The Phenomenology Of Metastable Liquids, Nicholas Bryan Weingartner

Arts & Sciences Electronic Theses and Dissertations

The glass transition remains one of the great open problems of modern physics. This dissertation aims to increase understanding of this topic by studying the rich phenomenology of supercooled liquids, the metastable precursors to the glassy state. Principally, we aim to discover what underlying physics leads to the dramatic, non-Arrhenius increase of the viscosity and relaxation time of supercooled liquids, and what thermodynamic properties govern this physics. We propose a novel framework and associated viscosity function applicable to all supercooled liquids/glassy systems, and rigorously assess both the performance and implications of this model. We demonstrate that the theoretical framework uncovers …

Development Of A Long-Period Torsion Balance For Tests Of Einstein's Equivalence Principle And A Search For Normal Mode Torsional Oscillations Of The Earth, Michael David Abercrombie

Arts & Sciences Electronic Theses and Dissertations

This thesis describes the development of a torsion balance experiment designed to test Einstein's equivalence principle with unprecedented sensitivity, while also taking a novel approach to directly observe the normal mode torsional oscillations of the Earth. Accordingly, a model of the signal expected from a potential equivalence principle violation has been developed, as well as a multi-slit auto-collimating optical lever which possesses a resolution on the order of a nanoradian and a range of observation of 10 milliradians and is used to monitor the torsion balance. A torsion balance with a natural torsional frequency of ~104 Hz, signi_cantly below the …

Actin-Based Feedback Circuits In Cell Migration And Endocytosis, Xinxin Wang

Arts & Sciences Electronic Theses and Dissertations

In this thesis, we study the switch and pulse functions of actin during two important cellular processes, cell migration and endocytosis. Actin is an abundant protein that can polymerize to form a dendritic network. The actin network can exert force to push or bend the cell membrane. During cell migration, the actin network behaves like a switch, assembling mostly at one end or at the other end. The end with the majority of the actin network is the leading edge, following which the cell can persistently move in the same direction. The other end, with the minority of the actin …

Investigation Of Lung Structure-Function Relationships Using Hyperpolarized Noble Gases, Robert P. Thomen

Arts & Sciences Electronic Theses and Dissertations

Magnetic Resonance Imaging (MRI) is an application of the nuclear magnetic resonance (NMR) phenomenon to non-invasively generate 3D tomographic images. MRI is an emerging modality for the lung, but it suffers from low sensitivity due to inherent low tissue density and short T₂*. Hyperpolarization is a process by which the nuclear contribution to NMR signal is greatly enhanced to more than 100,000 times that of samples in thermal equilibrium. The noble gases ³He and ¹²⁹Xe are most often hyperpolarized by transfer of light angular momentum through the electron of a vaporized alkali metal to the noble …

A Molecular Dynamics Study Of The Structure-Dynamics Relationships Of Supercooled Liquids And Glasses, Ryan Joseph Soklaski

Arts & Sciences Electronic Theses and Dissertations

Central to the field of condensed matter physics is a decades old outstanding problem in the study of glasses – namely explaining the extreme slowing of dynamics in a liquid as it is supercooled towards the so-called glass transition. Efforts to universally describe the stretched relaxation processes and heterogeneous dynamics that characteristically develop in supercooled liquids remain divided in both their approaches and successes. Towards this end, a consensus on the role that atomic and molecular structures play in the liquid is even more tenuous. However, mounting material science research efforts have culminated to reveal that the vast diversity of …

Topics In Lattice Gauge Theory And Theoretical Physics, Javad Komijani

Arts & Sciences Electronic Theses and Dissertations

This dissertation contains two completely independent parts.

In Part 1,

I investigate effective field theories and their applications in lattice gauge theory.

Quantum chromodynamics (QCD) as a part of the standard model (SM) describes the physics of quarks and gluons.

There are several numerical and analytical methods to tackle the QCD problems.

Lattice QCD is the dominant numerical method.

Effective field theories,

on the other hand, provide analytic methods to describe the low-energy dynamics of QCD.

To use the effective theories in lattice QCD,

I develop chiral perturbation theory for heavy-light mesons with staggered

quarks---an implementation of fermions on lattice. …

Enhanced Magnetism In Dy And Tb At Extreme Pressure, Jinhyuk Lim

Arts & Sciences Electronic Theses and Dissertations

At ambient pressure all lanthanide metals order magnetically at temperatures at or below ambient. The magnetic ordering is known to result from the indirect exchange interaction between localized 4f magnetic moments mediated by the surrounding conduction electrons, the so-called Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction. With the RKKY interaction the magnetic ordering temperature To is expected to be proportional to the de Gennes factor which is a function of the Landé g factor gJ and the total angular momentum J. For example, Gd has the highest value of To, 292 K, at ambient pressure as it has the largest de Gennes factor of …

Thermophysical Properties And Structural Evolution Of Supercooled Metallic Liquids, Matthew Blodgett

Arts & Sciences Electronic Theses and Dissertations

Metallic glasses (and glasses in general) offer unique material properties compared to their crystalline counterparts. Yet the physics of the glass transition remain poorly understood. By examining the evolution of properties in the liquid as it is cooled toward the glass transition we hope to discern how they relate to glass formation.

Of particular interest is the concept of kinetic fragility, first defined in terms of the viscosity behavior near the glass transition, and what it means for a high temperature liquid to be “fragile” or “strong.” This dissertation presents several studies of metallic liquids using the electrostatic levitation technique. …

Correlated Nanosims, Tem, And Xanes Studies Of Presolar Grains, Evan Edward Groopman

Arts & Sciences Electronic Theses and Dissertations

The objective of this thesis is to describe the correlated study of individual presolar grains via Nano-scale Secondary Ion Mass Spectrometry (NanoSIMS), Transmission Electron Microscopy (TEM), and Scanning Transmission X-ray Microscopy (STXM) utilizing X-ray Absorption Near Edge Structure (XANES), with a focus on connecting these correlated laboratory studies to astrophysical phenomena. The correlated isotopic, chemical, and microstructural studies of individual presolar grains provide the most detailed description of their formation environments, and help to inform astrophysical models and observations of stellar objects.

As a part of this thesis I have developed and improved upon laboratory techniques for micromanipulating presolar grains …

Neural Processing In The Three Layer Turtle Visual Cortex, Jeffrey Steven Pobst

Arts & Sciences Electronic Theses and Dissertations

In this thesis we investigate neural processing in turtle visual cortex. To this end, we characterize the nature of both spontaneous, ongoing neural activity as well as activity evoked by visual stimulation. Data are collected from whole brain eye-attached preparations, recording with extracellular and intracellular electrodes. We investigate the activity of action potentials as well as the slower local field potential activity.

To investigate response properties, we explore spatial properties of receptive fields, temporal properties of spontaneous and evoked activity, response adaptation, and correlations between different types of activity as well as between activity recorded in different regions.

To study …

Kinematic Modeling Of The Determinants Of Diastolic Function, Leonid Shmuylovich

Arts & Sciences Electronic Theses and Dissertations

Multiple modalities are routinely used in clinical cardiology to determine cardiovascular function, and many of the indexes derived from these modalities are causally interconnected. A correlative approach to cardiovascular function however, where indexes are correlated to disease presence and progression, fails to fully capitalize on the information content of the indexes.

Causal quantitative modeling of cardiovascular physiology on the other hand offers a predictive rather than accommodative approach to cardiovascular function determination. In this work we apply a kinematic modeling approach to understanding diastolic function. We discuss novel insights related to the physiological determinants of diastolic function, and define novel …

Tuning Electronic Correlation With Pressure, Gilberto Fernandes Lopes Fabbris

Arts & Sciences Electronic Theses and Dissertations

Strongly correlated electron systems display some of the most exotic ground states in condensed matter. In this thesis high pressure is used to tune the degree of electron correlations in systems of current interest. Their electronic and structural properties were investigated at high pressure using x-ray spectroscopy and scattering as well as transport techniques in a diamond anvil cell. The interplay between short- and long-range structural order, one-dimensional charge ordering, and superconductivity was studied in La_1.875Ba_0.125CuO₄. At ambient pressure, this material displays charge ordering at the onset of a low temperature structural phase transition, …

Comparison Of Conventional And Bayesian Analysis For The Ultrasonic Characterization Of Cancellous Bone, Amber Groopman

Arts & Sciences Electronic Theses and Dissertations

This dissertation investigates the physics underlying the propagation of ultrasonic waves in cancellous bone. Although quantitative ultrasound has the potential to evaluate bone quality even better than the current gold standard X-ray based modality, its clinical utility has been hampered by the incomplete understanding of the mechanisms governing the interaction between ultrasound and bone. Therefore, studies that extend the understanding of the fundamental physics of the relationship between ultrasound and trabecular bone tissue may result in improved clinical capabilities.

Ultrasonic measurements were carried out on excised human calcaneal specimens in order to study the effects of overlapping fast and slow …

X-Ray Polarimetry With X-Calibur, Qingzhen Guo

Arts & Sciences Electronic Theses and Dissertations

ABSTRACT

X-Ray Polarimetry with X-Calibur

by

Qingzhen Guo

Doctor of Philosophy in Physics, Washington University in St. Louis,

September, 2014. Professor Henric Krawczynski, Chair

X-ray polarimetry is a prime tool to investigate the unexplored compact sources and to provide crucial information that other techniques can not produce. By measuring the degree and orientation of the polarization of radiation from a cosmic source, unique inferences about the morphology and the magnetic field structure can be made.

Krawczysnki's group at Washington University is working on a uniquely sensitive scattering polarimeter, X-Calibur, to be used in the focal plane of a focusing X-ray …

Various Geometric Aspects Of Condensed Matter Physics, Zhenyu Zhou

Arts & Sciences Electronic Theses and Dissertations

Geometric aspect of condensed matter has arouse a lot of interests in recent years. The idea of Berry phase is highly appreciated in various systems. We explored the geometric features of two specific electron systems, fractional quantum Hall (FQH) states and d-wave superconducting states. For FQH states, we propose a two body operator which generates the geometric change of Laughlin state in the guiding center degrees of freedom on torus. This operator therefore generates the adiabatic evolution between Laughlin states on regular tori and the quasi-one-dimensional thin torus limit. For d-wave superconducting model, we study the local and topological features …

Biological Applications Of Extraordinary Electroconductance And Photovoltaic Effects In Inverse Extraordinary Optoconductance, Lauren C. Tran

Arts & Sciences Electronic Theses and Dissertations

The Extraordinary Electroconductance (EEC) sensor has been previously demonstrated to have an electric field sensitivity of 3.05V/cm in a mesoscopic-scale structure fabricated at the center of a parallel plate capacitor. In this thesis, we demonstrate the first successful application of EEC sensors as electrochemical detectors of protein binding and biological molecule concentration. Using the avidin derivative, captavidin, in complex with the vitamin biotin, the change in four-point measured resistance with fluid protein concentration of bare EEC sensors was shown to increase by a factor of four in the presence of biomolecular binding as compared to baseline. Calculations for approximate field …

Effective 1d Language For Fractional Quantum Hall States, John Flavin

Arts & Sciences Electronic Theses and Dissertations

In the theory of the fractional quantum Hall effect, much attention is paid to the correspondence between fractional quantum Hall wave functions and conformal blocks in certain rational conformal field theories (CFT). This correspondence is powerful, enabling the calculation of the fractional statistics of a state that would be difficult if not impossible to calculate directly from the wave functions. But it is, in general, conjectural, remaining without microscopic justification in many cases of interest, and involves heavy mathematical machinery. We detail an alternative method to calculate Abelian and non-Abelian fractional statistics, the coherent state method. The method relies on …