Physics Commons^™

Quantics Tensor Trains: The Study Of A Continuous Lattice Model And Beyond, Aleix Bou Comas

Dissertations, Theses, and Capstone Projects

This four-chapter dissertation studies the efficient discretization of continuous variable functions with tensor train representation. The first chapter describes all the methodology used to discretize functions and store them efficiently. In this section, the algorithm tensor renormalization group is explained for self-containment purposes. The second chapter centers around the XY model. Quantics tensor trains are used to describe the transfer matrix of the model and compute one and two-dimensional quantities. The one dimensional magnitudes are compared to analytical results with an agreement close to machine precision. As for two dimensions, the analytical results cannot be computed. However, the critical temperature …

A Causal Inference Approach For Spike Train Interactions, Zach Saccomano

Dissertations, Theses, and Capstone Projects

Since the 1960s, neuroscientists have worked on the problem of estimating synaptic properties, such as connectivity and strength, from simultaneously recorded spike trains. Recent years have seen renewed interest in the problem coinciding with rapid advances in experimental technologies, including an approximate exponential increase in the number of neurons that can be recorded in parallel and perturbation techniques such as optogenetics that can be used to calibrate and validate causal hypotheses about functional connectivity. This thesis presents a mathematical examination of synaptic inference from two perspectives: (1) using in vivo data and biophysical models, we ask in what cases the …

Exciton Dynamics, Interaction, And Transport In Monolayers Of Transition Metal Dichalcogenides, Saroj Chand

Dissertations, Theses, and Capstone Projects

Monolayers Transition metal dichalcogenides (TMDs) have attracted much attention in recent years due to their promising optical and electronic properties for applications in optoelectronic devices. The rich multivalley band structure and sizable spin-orbit coupling in monolayer TMDs result in several optically bright and dark excitonic states with different spin and valley configurations. In the proposed works, we have developed experimental techniques and theoretical models to study the dynamics, interactions, and transport of both dark and bright excitons.

In W-based monolayers of TMDs, the momentum dark exciton cannot typically recombine optically, but they represent the lowest excitonic state of the system …

Nonlinear Processes In Room Temperature Exciton-Polaritons, Prathmesh Deshmukh

Dissertations, Theses, and Capstone Projects

Strong light-matter coupling in solid state systems is an intriguing process that allows one to exploit the advantages of both light and matter. In this context, microcavities have become essential platforms for studying the strong coupling regime, where hybrid light-matter states known as exciton-polaritons form, leading to enhanced light matter interaction, modified material properties, and novel quantum phenomena. In this thesis, we explore the phenomenology of exciton-polaritons in strained TMD microcavities, 2D perovskites, fluorescent proteins and organic dyes encompassing thermalization, polariton lasing, and the observation of nonlinear effects.

Transition metal dichalcogenides (TMDs) have emerged as a remarkable class of two- …

Quantifying Temperature-, Pressure-, And Nuclear Quantum Effects On Hydrophobic And Hydrophilic Water-Mediated Interactions, Justin T. Engstler

Dissertations, Theses, and Capstone Projects

Water-mediated interactions (WMIs) are responsible for diverse processes in aqueous solutions, including protein folding and nanoparticle aggregation. WMI may be affected by changes in temperature and pressure, and hence, they can alter chemical/physical processes that occur in aqueous environments. Traditionally, attention has been focused on hydrophobic interactions while, in comparison, the role of hydrophilic and hybrid (hydrophobic–hydrophilic) interactions have been mostly overlooked. Here, we study the role of T and P on the WMI between nanoscale (i) hydrophobic–hydrophobic, (ii) hydrophilic–hydrophilic, and (iii) hydrophilic–hydrophobic pairs of (hydroxylated/non-hydroxylated) graphene-based surfaces. We find that hydrophobic, hydrophilic, and hybrid interactions are all sensitive to …

Centrality Effects On Heavy-Flavor Quark Production And Invariant Yield In Phenix Proton–Gold Collisions At Center-Of-Mass Energy 200 Gev, And Assembly, Testing, Calibration, And Installation Of The Sphenix Hadronic Calorimeters, Daniel Richford

Dissertations, Theses, and Capstone Projects

Hadrons created in heavy-ion collisions interact with the open color-charge of the quark-gluon plasma through their constituent quarks. The medium imparts substantial modifications to heavy-flavor hadrons' momentum spectra. For collisions of small systems, the centrality of those collisions affects both the production of heavy-quarks and the medium modifications that the heavy-quarks experience. This analysis uses the PHENIX detector at the Relativistic Heavy Ion Collider, which collected data from proton--gold collisions in 2015, with a trigger to preference the collection of the five-percent most-central collisions. This analysis uses the distance-of-closest-approach of electron tracks to study semileptonic decays from charm and bottom …

Dynamics Of Spin And Charge Of Color Centers In Diamond Under Cryogenic Conditions, Richard G. Monge

Dissertations, Theses, and Capstone Projects

Individual quantum systems in semiconductors are currently the most sought-after platform for applications in quantum science. Most notably, the nitrogen-vacancy (NV) center in diamond features a defect deep within the electronic bandgap, making it amenable for precise manipulation to help pave the way to perform fundamental quantum physics experimentation. The NV center also offers long coherence times and versatile spin-dependent fluorescent properties, making it an ideal candidate for a nanoscale magnetometer. Furthermore, multi-color excitation offers deterministic charge state manipulation. While ambient operation has been key to their appeal, bringing NVs to cryogenic conditions opens new opportunities for alternate forms of …

The Role Of Nuclear Quantum Effects In Supercooled Water And Amorphous Ice, Ali H. Eltareb

Dissertations, Theses, and Capstone Projects

Water is one of the most important substances on Earth and plays a fundamental role in numerous scientific and engineering applications. Interestingly, water behaves much differently than other liquids. For example, water shows an anomalous density maximum at 277 K, the solid phase (ice) is less denser than the liquid, and its thermodynamic response functions, such as the specific heat C_P and isothermal compressibility κ_T, also increase anomalously upon cooling. In the glassy state, water can exist in two different forms, low-density and high-density amorphous ice (LDA and HDA). While water has been scrutinized for many centuries, …

Phase Transitions And Thermal Stability Of The Magnetic Dual Chiral Density Wave Phase In Cold, Dense Qcd, William G. Gyory

Dissertations, Theses, and Capstone Projects

The correct description of strongly interacting matter at extreme densities and low temperatures remains poorly understood. We analyze the magnetic dual chiral density wave (MDCDW) phase, an inhomogeneous chiral condensate that arises in cold, dense quark matter in a magnetic field. We first review the background theory and derive the free energy of the condensate. Then we show how the phase transitions can be studied using a generalized Ginzburg-Landau expansion, and we derive a convenient all-orders formula for the coefficients. Using these tools, we compute the order parameters, critical temperature, and threshold temperature over a range of chemical potentials and …

Tunable Linear And Nonlinear Metasurfaces Based On Hybrid Gold-Graphene Plasmons, Matthew Feinstein

Dissertations, Theses, and Capstone Projects

Optical Metasurfaces are planar structures that are patterned with subwavelength structures and are very thin compared to the wavelength of light. Despite their thinness, these structured materials can strongly interact with incident light to effect the functionalities of conventional optical components, such as rotation of the polarization state, beam steering, lensing, spectral filtering, and holography, to name a few. Metasurfaces can also facilitate nonlinear optical effects, such as the mixing of beams at different frequencies to generate a beam at a new frequency.

The ability to alter the behavior of a metasurface during operation is highly desired for applications such …

Hydrodynamic And Physicochemical Interactions Between An Active Janus Particle And An Inactive Particle, Jessica S. Rosenberg

Dissertations, Theses, and Capstone Projects

Active matter is an area of soft matter science in which units consume energy and turn it into autonomous motion. Groups of these units – whether flocks of birds, bacterial colonies, or even collections of synthetically-made active particles – may exhibit complex behavior on large scales. While the large-scale picture is of great importance, so is the microscopic scale. Studying the individual particles that make up active matter will allow us to understand how they move, and whether and under what circumstances their activity can be controlled.

Here we delve into the world of active matter by studying colloidal-sized (100 …

The Study Of Excitons In 2d Novel Materials And Their Van Der Waals Heterostructures In The Magnetic Field, Anastasia Spiridonova

Dissertations, Theses, and Capstone Projects

This research focuses on the direct and indirect excitons in Rydberg states in monolayers, bilayers, and van der Waals heterostructures composed of 2D semiconductors in the presence of the external magnetic field. In our work, we report binding energies of direct and indirect excitons in Rydberg states, the energy contribution from the magnetic field to the binding energies of magnetoexcitons, and diamagnetic coefficients (DMCs) of magnetoexcitons.

We study isotropic materials: transition metal dichalcogenides, TMDCs (WSe₂, WS₂, MoSe₂, MoS₂), and Xenes (silicene, germanene, stanene), and anisotropic materials: phosphorene and transition metal trichalcogenides, TMTCs …

Characterization Of Boreal-Arctic Vegetation Growth Phases And Active Soil Layer Dynamics In The High-Latitudes Of North America: A Study Combining Multi-Year In Situ And Satellite-Based Observations, Michael G. Brown

Dissertations, Theses, and Capstone Projects

This dissertation examined the seasonal freeze/thaw activity in boreal-Arctic soils and vegetation physiology in Alaska, USA and Alberta, Canada, using in situ environmental measurements and passive microwave satellite observations. The boreal-Arctic high-latitudes have been experiencing ecosystem changes more rapidly in comparison to the rest of Earth due to the presently warming climatic conditions having a magnified effect over Polar Regions. Currently, the boreal-Arctic is a carbon sink; however, recent studies indicate a shift over the next century to become a carbon source. High-latitude vegetation and cold soil dynamics are influenced by climatic shifts and are largely responsible for the regions …

Dynamics In Designed Elastins And Enzymes, Jonathan M. Preston

Dissertations, Theses, and Capstone Projects

In this dissertation I present experimental results on the structure and dynamics of elastin, an elastomeric extracellular component in vertebrates that, in mammals, provides structure and elasticity to the circulatory system, lungs, skin and joints. These experiments, using a set of designed elastin like proteins with properties analogous to the natural protein, show that elastin is highly disordered and connect this disorder to its mechanism of assembly and elasticity. In addition, I also present preliminary work on imparting flexibility into a set of computationally designed metalloenzymes to broaden the range of catalytic activities they perform.

One-Loop Corrections To Dihadron Production In Dis At Small X, Filip Bergabo

Dissertations, Theses, and Capstone Projects

We calculate the one-loop corrections to dihadron production in Deep Inelastic Scattering (DIS) at small x using the Color Glass Condensate formalism. We show that all UV and soft singularities cancel while the collinear divergences are absorbed into quark and anti quark-hadron fragmentation functions. Rapidity divergences lead to JIMWLK evolution of dipoles and quadrupoles describing multiple-scatterings of the quark anti-quark dipole on the target proton/nucleus. The resulting cross section is finite and can be used for phenomenological studies of dihadron angular correlations at small x in a future Electron-Ion Collider (EIC).

Beam-Based Target Alignment For Mu2e, Helenka Casler

Dissertations, Theses, and Capstone Projects

The Mu2e Experiment is a precision experiment at Fermi National Accelerator Laboratory, searching for charged lepton flavor violation (CLFV) in the conversion of a muon to an electron in the presence of an atomic nucleus. In order to achieve the expected single-event sensitivity of 3 × 10^-17 , Mu2e will require an intense muon beam, generated via pion decay. These pions are the product of a proton beam striking a radiatively-cooled tungsten target. In order to maximize pion production and prevent target failure, the beam will have to be aligned with the target center to within 0.5 mm. The …

Revealing The Three-Dimensional Magnetic Texture With Machine Learning Models, Shihua Zhao

Dissertations, Theses, and Capstone Projects

Revealing three-dimensional (3D) magnetic textures with vector field electron tomography (VFET) is essential in studying novel magnetic materials with topologically protected spin textures potentially being used in the next-generation semiconductor industry. In this dissertation, we use machine learning (ML) models to reconstruct 3D magnetic textures from electron holography (EH) data.

We can feed the EH data, a series of two-dimensional (2D) phasemaps, into a neural network (NN) architecture directly or feed the EH data into a conventional VFET and then feed the reconstructed results into a NN. Thus, perceptive NN, either a simple convolutional neural network (CNN) or Unet architecture, …

A Quantum Approach To Language Modeling, Constantijn Van Der Poel

Dissertations, Theses, and Capstone Projects

This dissertation consists of six chapters. . . Chapter 1: We introduce language modeling, outline the software used for this thesis, and discuss related work. Chapter 2: We will unpack the transition from classical to quantum probabilities, as well as motivate their use in building a model to understand language-like datasets. Chapter 3: We motivate the Motzkin dataset, the models we will be investigating, as well as the necessary algorithms to do calculations with them. Chapter 4: We investigate our models’ sensitivity to various hyperparameters. Chapter 5: We compare the performance and robustness of the models. Chapter 6: We conclude …

Astrophysics, Cosmology And Particle Phenomenology At The Energy Frontier, Jorge Fernandez Soriano

Dissertations, Theses, and Capstone Projects

This dissertation consists of two parts, treating significantly separated fields. Each part consists on several chapters, each treating a somewhat isolated topic from the rest. In each chapter, I present some of the work developed during my passage through the graduate program, which has mostly been published elsewhere.

Part I – Cosmic Rays and Particle Physics

• Chapter 1: In this chapter we present an introduction to the topic of cosmic ray physics, with an special focus on the so-called ultra high energy cosmic rays: their potential origins, effects during their propagation between their sources and Earth, the different techniques used …

Using Protonation Microstates And Hydrogen Bond Networks To Track Proton Transfer Pathways In Complex I, Umesh Khaniya

Dissertations, Theses, and Capstone Projects

Complex I, NADH-ubiquinone oxidoreductase, is the first enzyme in the mitochondrial and bacterial aerobic respiratory chain. It pumps four protons through four transiently open pathways from the high pH, negative, N- side of the membrane to the positive, P-side driven by the exergonic transfer of electrons from NADH to a quinone. Three protons transfer through subunits descended from Mrp antiporters, while the fourth, E-channel is unique. Because of the complex possible paths thorough the many buried polar residues and lack of high-resolution crystal structure, the path for protons through the E-channel is elusive.

In this dissertation, the E-channel proton pumping …

Nmr Characterization Of Novel Materials For Battery Electrolyte Applications, Sahana Bhattacharyya

Dissertations, Theses, and Capstone Projects

The extensive application of renewable and non-renewable energy storage devices in commercial products and services and the global warming have created significant motivations to accelerate research in battery technology. In addition, the risk factors generated by the high heat generation and flammability of the batteries are being addressed by inventing new renewable or non-renewable energy resources that do not release greenhouse gases into the atmosphere. This thesis discusses the applications of Nuclear Magnetic Resonance (NMR) Spectroscopy in characterizing and understanding novel battery materials as potential battery electrolytes. Works discussed include: the variable temperature characterization of water-based solid polymer electrolyte for …

Driven Dipolaritons In Van Der Waals Transition Metal Dichalcogenide Heterostructures: Properties And Applications, Patrick Serafin

Dissertations, Theses, and Capstone Projects

The need for advances in optical computation leads us toward the investigation of novel methods of re-routing light in optical circuits. The behavior and properties of electrically driven exciton-dipolaritons in van der Waals transition metal dichalcogenides are investigated as a platform for realizing working elements of a polaritronic transistor. In this work, we consider exciton-dipolaritons, which are three-way superposition of cavity photons, direct excitons, and indirect excitons in a bilayer semiconducting system embedded in an optical microcavity. We start by providing motivation for our study of polaritons and then survey the fundamental properties of exciton-dipolaritons. We also survey the basic …

Control Of Nonlinear Properties Of Van Der Waals Materials, Rezlind Bushati

Dissertations, Theses, and Capstone Projects

Van der Waals materials are a broad class of materials that exhibit unique optoelectronic properties. They provide a rich playground for which they can be integrated into current on-chip devices due to their nanometer-scale size, and be utilized for studying fundamental physics. Strong coupling of emitters to microcavities provides many opportunities for new exotic physics through the formation of hybrid quasi-particles exciton-polaritons. This thesis
focuses on exploring and enhancing nonlinearity of van der Waals materials through strongly coupling to microcavities. By taking advantage of the stacking order of TMDs, we show intense second-harmonic generation from bulk, centrosymmetric TMD systems. In …

The Separation Of Charm And Bottom Decays Measured In P+Au Collisions At 200 Gev, Zhiyan Wang

Dissertations, Theses, and Capstone Projects

It has long been observed experimentally, from previous heavy-flavor electron measurements, that heavy quarks are subject to substantial modifications of their momentum spectrum. Using the PHENIX detector at the Relativistic Heavy Ion Collider (RHIC), measurements of the production of open heavy flavor hadrons with charm and bottom quarks in p+Au collisions at 200 GeV are studied and presented in this thesis. Distance of closest approach analysis of electron tracks is used to study the semileptonic decay electrons from charm and bottom hadrons. The results include invariant yield and fraction of bottom electrons. In addition to the p+p and Au+Au collisions’ …

Magnetic Field Effects On The Physics Of Neutron Stars, Aric A. Hackebill

Dissertations, Theses, and Capstone Projects

In the context of neutron stars (NS), dense-magnetized quark and hadron models have been well studied under the assumption that the system's pressures are isotropic. However, the pressures determined from semi-classical statistical averaging of the energy momentum tensor in the presence of a uniform background magnetic field are anisotropic with different pressures arising along and perpendicular to the magnetic field direction. Since large magnetic fields are expected to be present in the interior of NS, it is important to understand the roll the pressure anisotropy plays. While considering the pressure anisotropy, we revisit some important calculations in NS physics.

We …

Electron Transport In Quantum Systems With Interaction, Sara Abedi

Dissertations, Theses, and Capstone Projects

No abstract provided.

Engineering Rare-Earth Based Color Centers In Wide Bandgap Semiconductors For Quantum And Nanoscale Applications, Gabriel I. López-Morales

Dissertations, Theses, and Capstone Projects

For many years, atomic point-defects have been readily used to tune the bulk properties of solid-state crystalline materials, for instance, through the inclusion of elemental impurities (doping) during growth, or post-processing treatments such as ion bombardment or high-energy irradiation. Such atomic point-defects introduce local ‘incompatible’ chemical interactions with the periodic atomic arrangement that makes up the crystal, resulting for example in localized electronic states due to dangling bonds or excess of electrons. When present in sufficient concentrations, the defects interact collectively to alter the overall bulk properties of the host material. In the low concentration limit, however, point-defects can serve …

Removal Of Anisotropic Background From Neutral Pion And Tagged Direct Photon–Hadron Correlations Of Au+Au 200 Gev Collisions, Zachary Rowan

Dissertations, Theses, and Capstone Projects

A reaction plane dependent event mixing technique is developed to remove the collective background from two particle correlation measurements in heavy ion collisions. The method eliminates the need for any external flow measurements and is well suited for studying the path length dependence of particle production in quark-gluon plasma. Central to mid-central, as well as in vs out-of-plane, per neutral pion trigger integrated away-side hadron yield comparisons are made. Results suggest a significant path length dependent partonic energy loss in the medium. A tagging method is also introduced to measure the direct photon yield for various collision criteria. Direct photon …

The Interaction Of Different Primary Producers And Physical And Chemical Dynamics Of An Urban Shallow Lake, Majid Sahin

Dissertations, Theses, and Capstone Projects

An artificial urban shallow lake, Prospect Park Lake (PPL), is situated on a terminal moraine in Brooklyn New York, and supplied with municipal water treated with ortho-phosphates. The constant input of the phosphate nutrient is the primary source of eutrophication in the lake. The numerous pools along the water course houses various aquatic phototrophs, which influence the water quality and the state of the system, driving conditions into favoring the survival of their species. In the first half of the dissertation, the focus of the project is on analyzing how the different primary producers in different regions of PPL affect …

Stability Of Two-Dimensional Magnetic Skyrmions, Amel Derras-Chouk

Dissertations, Theses, and Capstone Projects

Magnetic skyrmions are whirls formed by magnetic moments in a crystal. They have attracted attention largely due to their topological protection, which provides an avenue for technology like next-generation memory storage. The idea of topologically protected solutions of a quantum field theory was originally proposed by Tony Skyrme when he developed a model to explain the stability of hadrons in particle physics. His work has extended far beyond his original intent to several areas of condensed matter physics. Here we focus on skyrmions in magnetic materials.

Skyrme's original theory modeled excitations which exist in three spatial dimensions, a requirement for …