Quantum Physics Commons^™

Josephson Junctions: Fabrication And Applications For The Axion Dark Matter Experiment, Jonah M. Sachs

Senior Honors Papers / Undergraduate Theses

The observation of axions could revolutionize the world of physics. Through microwave frequency cavity readout of the photons associated with these axions, the ADMX project at WashU utilizes multiple different forms of the Josephson junction (JJ), a superconductive circuit element. The physics behind the JJ are essential to understanding its operation for resonant cavity readout in addition to parametric amplification. Parametric amplifiers produced using JJs can approach the signal-to-noise ratio set by quantum mechanics, and prove essential for the amplification chain used by the ADMX experiment for axionic detection. The limits of these amplifiers are set by the noise tuning …

Optical Spring Tracking For Enhancing Quantum-Limited Interferometers, Scott M. Aronson

LSU Doctoral Dissertations

Gravitational waves were first predicted by Albert Einstein in 1916. Calculations in the 1970s by Rainer Weiss showed an interferometer of sufficient size could realistically detect gravitational waves, which led to a grant by the National Science Foundation (NSF). With steady progress and over decades of funding by the NSF, the construction of two full scale 4km interferometers was approved and began construction in 1994. This project, coined LIGO the Laser Interferometer Gravitational-wave Observatory, came to be a worldwide collaboration of scientists dedicated to the discovery and study of gravitational waves. In 2015, both LIGO detectors detected a coincident inspiral …

How Do We Observe Relational Observables?, Emily Adlam

Mathematics, Physics, and Computer Science Faculty Articles and Research

In theories with a diffeomorphism symmetry, such as general relativity and canonical quantum gravity, it is often proposed that the empirical content is encoded in relational observables. But how do relational observables actually make contact with experience? I argue that this question can only be answered by providing a schematization of the observer which is appropriate for the context of a diffeomorphism-invariant theory. I suggest that this may require us to move away from a ‘passive awareness’ conception of consciousness towards a more agential conception, because there is a clear sense in which an embodied agent must experience herself as …

Artificially Intelligent Maxwell's Demon For Optimal Control Of Open Quantum Systems, Paolo A. Erdman, Robert Czupryniak, Bibek Bhandari, Andrew N. Jordan, Frank Noé, Jens Eisert, Giacomo Guarnieri

Mathematics, Physics, and Computer Science Faculty Articles and Research

Feedback control of open quantum systems is of fundamental importance for practical applications in various contexts, ranging from quantum computation to quantum error correction and quantum metrology. Its use in the context of thermodynamics further enables the study of the interplay between information and energy. However, deriving optimal feedback control strategies is highly challenging, as it involves the optimal control of open quantum systems, the stochastic nature of quantum measurement, and the inclusion of policies that maximize a long-term time- and trajectory-averaged goal. In this work, we employ a reinforcement learning approach to automate and capture the role of a …

Measurement Time Of Weak Measurements On Large Entangled Systems, Truong-Son P. Văn, Andrew N. Jordan, David W. Snoke

Mathematics, Physics, and Computer Science Faculty Articles and Research

It is well established that starting only with strong, projective quantum measurements, experiments can be designed to allow weak measurements, which lead to a random walk between the possible final measurement outcomes. However, one can ask the reverse question: starting with only weak measurements, can all the results of standard strong measurements be recovered? Prior work has shown that some results can be, such as the Born rule for the probability of measurement outcomes as a function of wave intensity. In this paper, we show that another crucial result can be reproduced by purely weak measurements, namely, the collapse of …

Layout-Aware Quantum Circuitry And Algorithmic Extensions To Grover's Algorithm, Ali Al-Bayaty

Dissertations and Theses

Lov K. Grover introduced, in 1996, Grover's algorithm as a quantum search algorithm to find all solutions for quantum oracles representing classical problems. My research observed that the Grover diffusion operator of Grover's algorithm gives wrong solutions when Boolean oracles are designed in some logical structures. Therefore, I invented the new "controlled-diffusion operator" for Boolean oracles as a new approach for Grover's algorithm that always correctly solves the problem of Grover's algorithm.

Another important problem in quantum computing is designing reliable and cost-effective quantum gates using reversible binary logic. In classical logic design, the stage of logic design can be …

Quantum Control And Simulation Using Hamiltonian Engineering In Solid-State Nmr, Linta Joseph

Dartmouth College Ph.D Dissertations

Lattices of dipolar coupled nuclear spins in natural crystals are large, interacting quantum systems -- ideal platforms to simulate non-equilibrium many-body dynamics. Using the magnetic resonance toolkit, which includes Dynamic Nuclear Polarization (DNP), Hamiltonian engineering, and multiple-quantum Nuclear Magnetic Resonance (NMR) experiments, we study aspects of coherent control, manipulation, and readout of the complex dynamics of the spin system in NMR quantum simulation.

First, applying Hamiltonian engineering sequences, we control the system evolution. Specifically, we use a combination of numerical simulations and NMR experiments on adamantane to evaluate and compare the performance of several known sequences that aim to suppress …

The Metaphysics Of Time Within Physics, Mohamed Ahmed

Theses and Dissertations

The starting point of this thesis is to shed some light on the metaphysical nature of time by reflecting on the physics of time. The aim of this approach is not to [dis]prove or defend a metaphysical position but rather to elucidate the metaphysical position that underlies [or is compatible with] our best scientific theories. This task will be demanding, not only because our best theories may carry different interpretations of their underlying temporal structure but also because there seems to be a conceptual conflict/incompatibility between the notion of time in relativity and quantum mechanics, which are the two major …

Critical Behavior Ofthedilutedquasi-Onedimensionalquantum Ising Model, Logan Bradley Sowadski

Masters Theses

We explore the phase transition in the diluted quasi-one-dimensional quantum Ising model. We begin by giving an introduction to the Ising model followed by derivations of the properties and observables. A brief overview of Monte-Carlo simulations is also given focusing on two algorithms that make simulations for physically realizable systems possible, the Metropolis and Wolff algorithms. We finally discuss the concept of random disorder in the system and the effects this can have on the bulk of the system.

These concepts are then directly applied to a quasi-one-dimensional Ising model. Motivated by recent experiments on the spin-chain material cobalt niobate, …

A Fault-Tolerant Exchange-Coupled Spin-Ensemble Qubit At Elevated-Temperatures, Aniruddha Chakraborty

Theses and Dissertations

This thesis introduces a novel qubit architecture: the ferromagnetic exchange-coupled spin ensemble qubit (E-qubit), designed to address the noise-induced instability. In this work, the time evolution of the ensemble’s density matrix is studied using the Liouville–von Neumann equation. To benchmark against a single-spin qubit, the gate fidelity of an E-qubit is computed in the presence of thermal noise. Coherence time is also analyzed under identical thermal condition and a linear scaling is observed with qubit size . The results show that, at 6 K , the gate fidelity error (0.7 % ) of the seven- spin ensemble is an order …

Quantum-Mechanical Definition Of The Classical Scalar Potential In Schrödinger-Pauli And Schrödinger Theory, Viraht Sahni

Publications and Research

According to the Bohr correspondence principle, the external temporal scalar potential in the classical equation of motion is replicated in quantum theory as a multiplicative operator. An equivalent quantum-mechanical definition of the scalar potential in Schrödinger-Pauli/Schrödinger theory is provided. The potential is a known universal functional of the wave function. At each instant of time, it is the work done in a conservative “classical” field representative of internal properties of the system: Pauli and Coulomb correlations, kinetic effects, the density, the Lorentz force, an internal magnetic component, and the current density response. The Hamiltonians are thus rewritten in a …

Mathematics And Determinism: Chaos, Quantum Mechanics, And The Limits Of Predictive Structure, Jackson T. Salumbides

CMC Senior Theses

This thesis examines the relationship between mathematics and determinism by analyzing how chaos theory, quantum mechanics, and formal mathematical limits challenge traditional conceptions of predictability and causal structure. Chaos theory shows that deterministic systems can exhibit practical unpredictability due to sensitivity to initial conditions. Quantum mechanics introduces probabilistic outcomes that complicate deterministic interpretation, though alternative frameworks such as Bohmian mechanics and superdeterminism attempt to restore determinism at conceptual cost. Additionally, results from mathematical logic, including Gödel’s incompleteness theorems and Turing’s undecidability, demonstrate intrinsic limitations on what can be deduced or computed, even in fully deterministic systems. By synthesizing these areas, …

Constructing Hamiltonians Using A Wannier Basis Set To Study Localized Electronic Interactions Using A Variational Quantum Eigensolver, Matthew D. Bruenning

Graduate Theses/Dissertations

In this study, I demonstrate how Wannier basis sets can be used to construct a tight binding Hamiltonian that is localized in real space. This Hamiltonian can then be studied using the Variational Quantum Eigensolver (VQE), which is able to extract the minimized energy of the system. Unlike Bloch functions, Wannier functions are localized in real space, allowing each Hamiltonian element to represent orbital overlaps between neighboring atomic orbitals. This locality enables a substantial reduction in the Hamiltonian’s size by including only the orbital projections that contribute meaningfully to localized interaction energies, such as those involved in adsorption. As a …

Interactions And Applications Of Optical Angular Momentum In Magneto-Optical Material, Seth R. Nelson

Dissertations, Master's Theses and Master's Reports

This dissertation explores the interactions and applications of optical angular momentum within magneto-optical materials. Beginning with a theoretical and experimental analysis of multiple reflection and refraction phenomena within magneto-optical material. We derive and verify the dependence of refractive indices on optical spin angular momentum and magneto-optical magnetization, resulting in nonreciprocal elliptical and linear polarization beam splitting effects and wavevector discretization. We fabricate a magnetless slab waveguide isolator with minimal optical loss. Extending our study to optical orbital angular momentum, we introduce a perturbation to the electronic transition model in bismuth-substituted iron garnets. We demonstrate that this perturbation leads to nonreciprocal …

Qcd Factorization With Multihadron Fragmentation Functions, T. C. Rogers, M. Radici, A. Courtoy, T. Rainaldi

Physics Faculty Publications

Important aspects of quantum chromodynamics (QCD) factorization theorems are the properties of the objects involved that can be identified as universal. One example is that the definitions of parton densitiesand fragmentation functions for different types of hadrons differ only in the identity of the nonperturbative states that form the matrix elements, but are otherwise the same. This leads to independence of perturbativecalculations on nonperturbative details of external states. It also lends support to interpretations ofcorrelation functions as encapsulations of intrinsic nonperturbative properties. These characteristics have usually been presumed to still hold true in fragmentation functions even when the observed nonperturbative …

Measurement Of Spin-Density Matrix Elements In Δ⁺⁺ (1232) Photoproduction, F. Ayzal, C. S. Akondi, M. Albrecht, M. Amaryan, S. Arrigo, V. Arroyave, A. Asaturyan, A. Austregesilo, Z. Baldwin, F. Barbosa, J. Barlow, E. Barringa, R. Barsotti, D. Barton, V. Baturin, V. V. Berdnikov, T. Black, W. Boeglin, M. Boer, W. J. Briscoe, T. Britton, S. Cao, E. Chudakov, G. Chung, P. L. Cole, O. Cortes, V. Crede, M. M. Dalton, D. Darulis, A. Deur, S. Dobbs, A. Dolgolenko, M. Dugger, R. Dzhygadlo, D. Ebersole, M. Edo, H. Egiyan, T. Erbora, P. Eugenio, A. Fabrizi, C. Fanelli, S. Fang, J. Fitches, A. M. Foda, S. Furletov, L. Gan, H. Gao, A. Gardener, A. Gasparian, D. I. Glazier, C. Gleason, V. S. Goryachev, B. Grube, J. Guo, L. Guo, J. Hernandez, K. Hernandez, N. D. Hoffman, D. Hornidge, G. Hou, P. Hurck, A. Hurley, W. Imoehl, D. G. Ireland, M. M. Ito, I. Jaegle, N. S. Jarvis, T. Jeske, M. Jing, R. T. Jones, V. Kakoyan, G. Kalicy, V. Khachatryan, C. Kourkoumelis, A. Laduke, I. Larin, D. Lawrence, D. I. Lersch, H. Li, B. Liu, K. Livingston, G. J. Lolos, L. Lorenti, V. Lyubovitskij, R. Ma, D. Mack, A. Mahmood, H. Marukyan, V. Matveev, M. Mccaughan, M. Mccracken, C. A. Meyer, R. Miskimen, R. E. Mitchell, K. Mizutani, V. Neelamana, L. Ng, E. Nissen, S. Oreśić, A. I. Ostrovidov, Z. Papandreou, C. Paudel, R. Pedroni, L. Pentchev, K. J. Peters, E. Prathr, S. Rakshit, J. Reinhold, A. Remington, B. G. Ritchie, J. Ritman, G. Rodriguez, D. Romanov, K. Saldana, C. Salgado, S. Schadmand, A. M. Schertz, K. Scheuer, A. Schick, A. Schmidt, R. A. Schumacher, J. Schwiening, N. Septian, P. Sharp, X. Shen, M. R. Shepherd, J. Sikes, A. Smith, E. S. Smith, D. I. Sober, A. Somov, S. Somov, J. R. Stevens, I. I. Strakovsky, B. Sumner, K. Suresh, V.V. Tarasov, S. Taylor, A. Teymurazyan, A. Thiel, T. Viducic, T. Whitlatch, N. Wickramaarachchi, Y. Wunderlich, B. Yu, J. Zarling, Z. Zhang, X. Zhou, B. Zihlmann

Physics Faculty Publications

We measure the spin-density matrix elements (SDMEs) of the Δ⁺⁺ (1232) in the photoproduction reaction 𝛾p→π−Δ⁺⁺(1232) with the GlueX experiment in Hall D at Jefferson Lab. The measurement uses a linearly–polarized photon beam with energies from 8.2 to 8.8 GeV and the statistical precision of the SDMEs exceeds the previous measurement by three orders of magnitude for the momentum transfer squared region below 1.4 GeV². The data are sensitive to the previously undetermined relative sign between couplings in existing Regge-exchange models. Linear combinations of the extracted SDMEs allow for a decomposition into natural and unnatural–exchange amplitudes. We find that the …

Nonperturbative Aspects Of The Electromagnetic Pion Form Factor At High Energies, K. Quirion, C. Fernandez-Ramirez, V. Mathieu, G. Montaña, R. J. Perry, A. Pilloni, A. Rodas, V. Shastry, W. A. Smith, A. P. Szczepaniak, D. Winney

Physics Faculty Publications

The structure of hadronic form factors at high energies and their deviations from perturbative quantum chromodynamics provide insight on nonperturbative dynamics. Using an approach that is consistent with dispersion relations, we construct a model that simultaneously accounts for the pion wave function, gluonic exchanges, and quark Reggeization. In particular, we find that quark Reggeization can be investigated at high energies by studying scaling violation of the form factor.

Background-Field Method And Qcd Factorization, Ian Balitsky

Physics Faculty Publications

One method for deriving a factorization for QCD processes is to use successive integration over fields in the functional integral. In this approach, we separate the fields into two categories: dynamical fields with momenta above a relevant cutoff, and background fields with momenta below the cutoff. The dynamical fields are then integrated out in the background of the low-momentum background fields. This strategy works well at tree level, allowing us to quickly derive QCD factorization formulas at leading order. However, to extend the approach to higher loops, it is necessary to rigorously define the functional integral over dynamical fields in …

Avenues For A Number Density Interpretation Of Dihadron Fragmentation Functions, T. Rogers, A. Courtoy

Physics Faculty Publications

In this letter, we reassess the underlying physics of the number sum rule for dihadron fragmentation functions. We will argue that, currently, there are no settled constraints on what constitutes a valid number density interpretation for multihadron fragmentation functions. Imposing overly restrictive criteria might lead to misinterpretating the data. Most importantly, and on the basis of phenomenological analyses, the slightly varying definitions used in previous work are not excluded from possessing legitimate number density interpretations (up to the usual issues with ultraviolet divergences and renormalization), so long as they are paired with appropriate factorization theorems. We advocate for further theoretical …

Quantum Computation Of Su(2) Lattice Gauge Theory With Continuous Variables, Victor Ale, Nora M. Bauer, Raghav G. Jha, Felix Ringer, George Siopsis

Physics Faculty Publications

We present a quantum computational framework for pure SU(2) lattice gauge theory, using continuous variables instead of discrete qubits to represent the infinite-dimensional Hilbert space of the gauge fields. We consider a ladder as well as a two-dimensional grid of plaquettes, detailing the use of gauge fixing to reduce the degrees of freedom and simplify the Hamiltonian. We demonstrate how system dynamics, ground states, and energy gaps can be computed using the continuous-variable approach to quantum computing. Our results indicate that it is feasible to study non-Abelian gauge theories with continuous variables, providing new avenues for understanding the real-time dynamics …