Quantum Physics Commons^™

Computational Analysis Of Proton Conductivity Factors In Grotthuss-Style Mechanisms, Brock Dyer

Physics and Astronomy Honors Papers

The mechanism and fundamental molecular properties involved in proton conduction are discussed. Four calculable properties are presented: the proton affinity, binding energy (between protonated and neutral forms), intramolecular tautomerization barrier, and proton hopping barrier. An overview of the computational methods used in this thesis, including an introduction to the many-body Schrödinger equation and Density Functional Theory, as well as a look at Plane-Wave Density Functional Theory and Gaussian-Type Orbital Density Functional Theory are presented. 4,5-dimethyl-[1,2,3]-triazole is used as a model system, with 10 variations being generated with varying amounts and positions of fluorine substitution on the methyl groups. Preliminary calculations …

Multiparticle Quantum Plasmonics: Fundamentals And Applications, Mingyuan Hong

LSU Doctoral Dissertations

Quantum plasmonics explores the interaction between light and collective charge oscillations at metal-dielectric interfaces, enabling strong light confinement and enhanced quantum effects at the nanoscale. While traditional quantum optics has primarily focused on single-photon systems, an intermediate regime exists between classical and single-photon optics - multiparticle (or multiphoton) quantum optics. In this regime, classical light sources, when analyzed through techniques such as photon-number-resolving (PNR) detection and projective measurement, can reveal nontrivial quantum correlations. This thesis investigates how multiparticle quantum plasmonics harnesses these correlations to control quantum statistical properties, enhance coherence, and enable novel applications in quantum technologies.

In this thesis, …

Analyticity And Supershift With Regular Sampling, Fabrizio Colombo, Irene Sabadini, Daniele C. Struppa, Alain Yger

Mathematics, Physics, and Computer Science Faculty Articles and Research

The notion of supershift (in itself a generalization of the notion of superoscillation arising in quantum mechanics) expresses the fact that the sampling of a function in an interval allows to compute the values of the function far from the interval. In this paper, we study the relation between supershift and real analyticity. We use a classical result due to Serge Bernstein to show that real analyticity for a complex-valued function implies a strong form of supershift. On the other hand, we use a parametric version of a result by Leonid Kantorovitch to show that the converse is not true. …

Fiber Bundles Of The Complex Projective Space And Their Relation To Quantum Physics, Emily Wessman

Student Research Symposium

The complex projective space CPⁿ is the space of lines through the origin in Cⁿ⁺¹ with an equivalence relation defined by Z ~ λZ' for λ ∈ C*. We define the points under the equivalence relation as homogeneous coordinates, represented by [Z₀ : Z₁ : ... Z_n]. Since all Z,sub>i cannot equal zero, we can find a unique set of n coordinates (z₁,...,z_n) such that [Z₀ : Z₁ : ... : Z_n] ~ [1 : z₁ : ... : z_n] where z …

32 - Nested Two Level Decomposition For Quantum Computing, Andrew Maciejunes, John Stenger, Dan Gunlycke, Nikos Chrisochoides

Undergraduate Research Symposium

Abstract—We present a two-level decomposition strategy for solving the Vehicle Routing Problem (VRP) using the Quantum Approximate Optimization Algorithm (QAOA). A Problem-Level Decomposition (PLD) partitions a 9-node (72-qubit) VRP into smaller Traveling Salesman Problem (TSP) instances. Each TSP is then further simplified via Circuit-Level Decomposition (CLD), enabling execution on near-term quantum devices. Our approach achieves up to 90% reductions in circuit depth and qubit count. These results demonstrate the feasibility of solving VRPs previously too complex for quantum simulators and provide early evidence of potential quantum utility.

Optimizing Fisher Information In Quantum Technology, Bran Purvis

LSU Doctoral Dissertations

Fisher information is a statistical metric whose inverse represents a lower bound on the variance of an unbiased estimator. Naturally, in order to make the best estimates of a given unknown parameter, one would desire to find ways to minimize the value of this lower bound. Thus, the Fisher information can also be used to compare the quality of different estimators for a given parameter: whichever estimator has a lower value for its Fisher information must also provide better estimates. The same holds true in the framework of quantum information theory, where an analog to the Fisher information, dubbed quantum …

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 …

Large Negative Magnetoresistance In The Off-Stoichiometric Topological Semimetal Prsbxte2-X, Gokul Acharya, Krishna Pandey, M. M. Sharma, Jian Wang, Santosh Karki Chhetri, Md Rafique Un Nabi, Dinesh Upreti, Rabindra Basnet, Joshua Sakon, Jin Hu

Physics Faculty Publications and Presentations

Magnetic topological materials LnSbTe (Ln = lanthanide) have attracted intensive attention because of the presence of interplay between magnetism, topological, and electron correlations depending on the choices of magnetic Ln elements. Varying Sb and Te composition is an efficient approach to control structural, magnetic, and electronic properties. Here, we report on the composition-dependent properties in PrSbxTe2-x. We identified the tetragonal-to-orthorhombic structure transitions in this material system and very large negative magnetoresistance in the x = 0.3 composition, which might be ascribed to the coupling between magnetism and transport. Such unusual magnetotransport enables PrSbxTe2-x topological materials as a promising platform for …

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 …

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.

Frustrated Quantum Magnetism: The Interplay Of Isotropic And Anisotropic Interactions With Application To Α-Rucl3, Evan M. Wilson

UNF Graduate Theses and Dissertations

We investigate how anisotropic spin interactions, including Dzyaloshinskii–Moriya and Kitaev terms, manifest across quantum spin systems ranging from a single S = 1/2 dimer to molecular spin clusters and layered magnetic materials. Beginning with an exact analysis of the spin dimer, we demonstrate how singlet–triplet mixing induced by Dzyaloshinskii–Moriya interaction directly influences both thermodynamic observables and inelastic neutron scattering spectra. These microscopic fingerprints are then extended to trimer, tetramer, and tetrahedron geometries, where field-induced phase transitions and heat capacity anomalies reveal the interplay between isotropic Heisenberg and anisotropic Kitaev exchanges. In the frustrated zigzag honeycomb lattice, we show that a …

From Plasmonics To Superfluorescence: Engineering Light- Matter Interactions For Quantum Optical Phenomena, Aaron J. Wildenborg

Dissertations, Master's Theses and Master's Reports

This work presents different ways to engineer light-matter interactions by using nanostructures to exploit quantum-optical phenomena. First, sodium (Na) is predicted to be an ideal plasmonic material due to its ultra-low optical losses from the visible to the near-infrared (NIR). However, Na has practical limitations due to its high chemical reactivity. Using a scalable fabrication method for Na plasmonic nanostructures by combining phase-shift photolithography and a thermo-assisted spin-coating process, we produced nano-pit arrays of varying periodicities (300-600 nm), supporting tunable surface plasmon polariton (SPP) modes spanning visible to NIR. These structures demonstrated SPP resonances as narrow as 9.3 nm, with …

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, …