Quantum Physics Commons^™

Informationally-Optimal Measurements On Single-Qubit Systems, Adam V. Preston

Electronic Theses & Dissertations (2024 - present)

This thesis will focus on deriving informationally-optimal quantum state tomographic measurements on single-qubit systems, with the definition of informationally optimal to be defined as those measurements which maximize the average information gain. The informationally-optimal measurements that will be covered include projective measurements (formally building off of the work of [1] and putting it on firm, information-theoretic foundations), and more general types of quantum measurements called directional (also known as rank-one) positive operator-valued measure (POVM) measurements, and, finally, adaptive directional POVM measurements.

For projective measurements, we build on the work of Wootters and Fields ([1]) and show, via analytical methods and …

On Quantum Processes And The Epistemic Constraints, Varun Immanuel Premkumar Immanuel

Electronic Theses & Dissertations (2024 - present)

This doctoral dissertation on the foundations of quantum theory tells the story of a conceptual protagonist I have called “Epistemic Constraint.” Here, epistemic constraints are the definite, intersubjectively agreeable, ordinary-language conditions under which experiments are described.

The usual formulation of the quantum measurement problem, which I call the Schrodingerian measurement problem, has the structure of an anomaly: if we take quantum theory at face value, we expect no definite values, and yet we see definite values in experiments. The responses to this problem have been either to solve it or to dissolve it. These responses, which have taken the form …

Tracking A Precessing Quantum Spin System: Extracting Data From Quantum Systems Using Bayesian Analysis, John Kaminski

Electronic Theses & Dissertations (2024 - present)

The parameters that govern the evolution of a quantum system can be determined by making measurements on an ensemble of identically-prepared systems. However, there are times when we are unable to recreate the experiment and want to measure physical parameters from just a single particle. For example, we may wish to measure the mass to charge ratio of a particle based on its track through a bubble chamber. Recent research [11, 12, 16] has suggested that classical behavior, defined as phenomenon that does not violate macroscopic realism, does not arise simply as a consequence of a quantum system of many …

Scalable Single-Erbium Telecom Qudits With Record Room-Temperature Quantum Coherence In Silicon-Based Nanostructures, Alexander Kaloyeros

Electronic Theses & Dissertations (2024 - present)

Advancing quantum information science demands solid-state quantum systems that maintain long quantum coherence at elevated temperatures while supporting scalable, CMOS-compatible fabrication and telecom C-band operation. No existing platform has simultaneously achieved these requirements, as state-of-the-art demonstrations of coherent control of erbium ions, with an intrinsic telecom-band optical transition, have been confined to cryogenic temperatures below < 10 K under controlled vacuum conditions. This thesis introduces a new paradigm in which materials science and engineering provides the enabling pathway to quantum coherence.

A foundry-compatible nanofabrication approach, paired with targeted materials engineering, is developed to realize a new class of CMOS-scalable quantum system: arrays of spatially isolated single-erbium-ion qudits (five-level systems) embedded in silicon-based (e.g., silicon carbide (SiC) and SiC_xO_y) hollow nanopillars (HNPs). Non-lithographically …

Entropic Dynamics Approach To The Classical Limit Of Quantum Mechanics: Decoupling Of The Center Of Mass Motion For A Mesoscopic Particle, Fatimah Judayba

Electronic Theses & Dissertations (2024 - present)

In the Entropic Dynamics (ED) approach, quantum mechanics is derived from the principles of entropic inference and information geometry. The ED approach differs from other interpretations by making a clear commitment to distinguishing which variables are ontic (real) and which are epistemic. The classical limit for the center of mass (CM) coordinate is achieved for a large number of particles, M →∞, while Planck’s constant ℏ remains finite. Typically, the emergence of the classical limit requires decoherence through interactions with the external environment. In this work, we investigate whether the classical behavior of the CM coordinate in a mesoscopic system …

Entropic Foundation Of Finance And Physics: Securities Price Dynamics And Quantum Theory, Mohammad Abedi

Electronic Theses & Dissertations (2024 - present)

In many scientific and financial contexts, we must reason and make predictions under conditions of incomplete information. This dissertation develops Entropic Dynamics (ED) as a unified framework for deriving dynamical laws directly from principles of inference. Within this approach, probability distributions represent states of knowledge, and their evolution is determined through entropy maximization subject to relevant constraints. This leads to a novel concept of entropic time and a formulation of dynamics as an inferential process. In this talk, I will present how ED provides a common foundation across multiple domains. In physics, quantum dynamics for particles and scalar fields in …

Further Results On Learning Quantum Measurement Classes: Quantum Pac Model For Povm Hypothesis Classes, Arka Prabha Das

Electronic Theses & Dissertations (2024 - present)

This thesis investigates the problem of learning from quantum systems, where each example consists of a quantum state paired with a classical outcome. The task centers on choosing an effective measurement rule from a fixed set to enable accurate prediction of the classical outcome from the quantum state. A central focus lies in understanding whether joint measurement strategies that cannot be separated into local operations offer a real benefit in terms of the number of examples needed for successful learning. We examine conditions under which a non-separable measurement within a given hypothesis class achieves strictly better sample complexity bounds compared …

Development Of Group Iii-V Quantum Confinement-Enabled Detectors: Bias-Tunable Quantum Well Infrared Photodetector (Qwip) And Quantum Dot Scintillation Detector (Qdsd), Gyana R. Biswal

Electronic Theses & Dissertations (2024 - present)

This dissertation discloses the physics, fabrication, characterization, and analysis of two novel types of group III-V semiconductor detectors relying on quantum confinement of carriers, namely voltage-tunable quantum well infrared photodetectors (QWIP) and a high-yield ultrafast quantum dot scintillation detector (QDSD). Both QWIP and QDSD heterostructures presented here were grown on 3” GaAs (001) substrates using molecular beam epitaxy (MBE).

A major part of the dissertation focuses on development of the voltage-tunable QWIPs targeting detection in the mid-wave infrared region (MWIR) (3μm -5μm) and long-wave infrared region (LWIR) (8μm -12μm) with control of sensitivity by the applied bias. The QWIPs utilize …

Issues And Challenges In Silicon Based Quantum Computing, Rafia Ayub

Electronic Theses & Dissertations (2024 - present)

Silicon-based quantum computing has emerged as a promising platform for scalable and fault-tolerant quantum information processing. This thesis investigates the use of silicon quantum dots as qubits, addressing a key limitation in their implementation—charge noise and decoherence. We explore the physical and electronic properties of silicon quantum dots, focusing on their coherence times, tunability, and compatibility with existing semiconductor fabrication technologies. Through theoretical analysis and numerical simulations, we examine the impact of material imperfections and propose strategies to mitigate decoherence effects, thereby enhancing qubit stability. Additionally, we discuss potential pathways for integrating silicon quantum dots into large-scale quantum architectures. Our …

Integrable Deformations, T-Dualities And Higher Order Corrections In String Theory, Parita Shah

Electronic Theses & Dissertations (2024 - present)

This thesis explores the interplay of hidden symmetries and dualities in string theory, with a particular emphasis on the role of T-duality. As a fundamental symmetry of string theory, T-duality offers a powerful lens through which one can study integrability, solution-generating techniques, and quantum corrections, all essential aspects of modern string theoretic frameworks.

A central focus of this work is the application of the duality covariant formalism of Double Field Theory (DFT) to address problems involving integrable deformations and higher-order quantum corrections. We examine how generalized integrable models can be embedded into DFT and how the formalism captures hidden symmetries …

Informational Principles And Structures In Quantum Theory, Yang Yu

Electronic Theses & Dissertations (2024 - present)

This thesis examines the concept of information within the realm of quantum physics, investigating the nuanced relationship between information and physical laws as applied to quantum systems. With no consensus on a single definition of information in the physical sciences, our exploration is partitioned into two significant studies, each addressing distinct aspects of information in quantum contexts.

In the first study, we concentrate on the information that can be obtained from measurement results on identical quantum systems. The traditional approach of using Shannon entropy is limited due to its applicability primarily to discrete probability distributions. By incorporating a Bayesian update …