Quantum Physics Commons^™

Topics In Three-Dimensional Imaging, Source Localization And Super-Resolution, Zhixian Yu

Physics & Astronomy ETDs

The realization that twisted light beams with helical phasefronts could carry orbital angular momentum (OAM) that is in excess of the photon's spin angular momentum (SAM) has spawned various important applications. One example is the design of novel imaging systems that achieve three-dimensional (3D) imaging in a single snapshot via the rotation of point spread function (PSF).

Based on a scalar-field analysis, a particular simple version of rotating PSF imagery, which was proposed by my advisor Dr. Prasad, furnishes a practical approach to perform 3D source localization using a spiral phase mask that generates a combination of Bessel vortex beams. …

Experimental Evidence Supportive Of The Quantum Dna Model, F. Matthew Mihelic

Faculty Publications

The DNA molecule can be modeled as a quantum logic processor in which electron spin qubits are held coherently in each nucleotide in a logically and thermodynamically reversible enantiomeric symmetry, and can be coherently conducted along the pi-stacking interactions of aromatic nucleotide bases, while simultaneously being spin-filtered via the helicity of the DNA molecule. Entangled electron pairs can be separated by that spin-filtering, held coherently at biological temperatures in the topologically insulated nucleotide quantum gates, and incorporated into separate DNA strands during DNA replication. Two separate DNA strands that share quantum entangled electrons can be mitotically divided into individual cells, …

Unbounded Derivations Of C*-Algebras And The Heisenberg Commutation Relation, Lara M. Ismert

Department of Mathematics: Dissertations, Theses, and Student Research

This dissertation investigates the properties of unbounded derivations on C*-algebras, namely the density of their analytic vectors and a property we refer to as "kernel stabilization." We focus on a weakly-defined derivation δ_D which formalizes commutators involving unbounded self-adjoint operators on a Hilbert space. These commutators naturally arise in quantum mechanics, as we briefly describe in the introduction.

A first application of kernel stabilization for δ_D shows that a large class of abstract derivations on unbounded C*-algebras, defined by O. Bratteli and D. Robinson, also have kernel stabilization. A second application of kernel stabilization provides a sufficient condition …

Free Electron Sources And Diffraction In Time, Eric R. Jones

Department of Physics and Astronomy: Dissertations, Theses, and Student Research

The quantum revolution of the last century advanced synergistically with technology, for example, with control of the temporal and spatial coherence, and the polarization state of light. Indeed, experimental confirmation of the quirks of quantum theory, as originally highlighted by Einstein, Podolsky, and Rosen, through Bohm, and then Bell, have been performed with photons, i.e., electromagnetic wave packets prepared in the same quantum states. Experimental tests of quantum mechanics with matter wave packets have been limited due to challenges in preparing all of the packets with similar quantum states. While great strides have been made for trapped atoms and Bose-Einstein …

Topological Insulating States In Photonics And Acoustics, Xiang Ni

Dissertations, Theses, and Capstone Projects

Recent surge of interest in topological insulators, insulating in their interior but conducting at the surfaces or interfaces of different domains, has led to the discovery of a variety of new topological states, and their topological invariants are characterized by numerous approaches in the category of topological band theory. The common features shared by topological insulators include, the topological phase transition occurs if the bulk bandgap is formed due to the symmetries reduction, the topological invariants exist characterizing the global properties of the material and inherently robust to disorder and continuous perturbations irrespective of the local details. Most importantly, these …

The Nature Of The Heisenberg-Von Neumann Cut: Enhanced Orthodox Interpretation Of Quantum Mechanics, Ashok Narasimhan, Deepak Chopra, Menas Kafatos

Mathematics, Physics, and Computer Science Faculty Articles and Research

We examine the issue of the Heisenberg-von Neumann cut in light of recent interpretations of quantum eraser experiments which indicate the possibility of a universal Observer outside space-time at an information level of existence. The delayed-choice aspects of observation, measurement, the role of the observer, and information in the quantum framework of the universe are discussed. While traditional double-slit experiments are usually interpreted as indicating that the collapse of the wave function involves choices by an individual observer in space-time, the extension to quantum eraser experiments brings in some additional subtle aspects relating to the role of observation and what …

Induced Quantum Dot Probe For Material Characterization, Yun-Pil Shim, Rusko Ruskov, Hilary M. Hurst, Charles Tahan

Faculty Research, Scholarly, and Creative Activity

We propose a non-destructive means of characterizing a semiconductor wafer via measuring parameters of an induced quantum dot on the material system of interest with a separate probe chip that can also house the measurement circuitry. We show that a single wire can create the dot, determine if an electron is present, and be used to measure critical device parameters. Adding more wires enables more complicated (potentially multi-dot) systems and measurements. As one application for this concept we consider silicon metal-oxide-semiconductor and silicon/silicon-germanium quantum dot qubits relevant to quantum computing and show how to measure low-lying excited states (so-called "valley" …

Roadmap On Superoscillations, Michael Berry, Nicolay Zheludev, Yakir Aharonov, Fabrizio Colombo, Irene Sabadini, Daniele C. Struppa, Jeff Tollaksen, Edward T. F. Rogers, Fei Qin, Minghui Hong, Xiangang Luo, Roei Remez, Ady Arie, Jörg B. Götte, Mark R. Dennis, Alex M. H. Wong, George V. Eleftheriades, Yaniv Eliezer, Alon Bahabad, Gang Chen, Zhongquan Wen, Gaofeng Liang, Chenglong Hao, C-W Qiu, Achim Kempf, Eytan Katzav, Moshe Schwartz

Mathematics, Physics, and Computer Science Faculty Articles and Research

Superoscillations are band-limited functions with the counterintuitive property that they can vary arbitrarily faster than their fastest Fourier component, over arbitrarily long intervals. Modern studies originated in quantum theory, but there were anticipations in radar and optics. The mathematical understanding—still being explored—recognises that functions are extremely small where they superoscillate; this has implications for information theory. Applications to optical vortices, sub-wavelength microscopy and related areas of nanoscience are now moving from the theoretical and the demonstrative to the practical. This Roadmap surveys all these areas, providing background, current research, and anticipating future developments.

Realization Of Tensor Product And Of Tensor Factorization Of Rational Functions, Daniel Alpay, Izchak Lewkowicz

Mathematics, Physics, and Computer Science Faculty Articles and Research

We study the state space realization of a tensor product of a pair of rational functions. At the expense of “inflating” the dimensions, we recover the classical expressions for realization of a regular product of rational functions. Under an additional assumption that the limit at infinity of a given rational function exists and is equal to identity, we introduce an explicit formula for a tensor factorization of this function.

Improving The Readout Of Semiconducting Qubits, Matthew Jon Curry

Physics & Astronomy ETDs

Semiconducting qubits are a promising platform for quantum computers. In particular, silicon spin qubits have made a number of advancements recently including long coherence times, high-fidelity single-qubit gates, two-qubit gates, and high-fidelity readout. However, all operations likely require improvement in fidelity and speed, if possible, to realize a quantum computer.

Readout fidelity and speed, in general, are limited by circuit challenges centered on extracting low signal from a device in a dilution refrigerator connected to room temperature amplifiers by long coaxial cables with relatively high capacitance. Readout fidelity specifically is limited by the time it takes to reliably distinguish qubit …

Testing Quantum Coherence In Stochastic Electrodynamics With Squeezed Schrödinger Cat States, Wayne Cheng-Wei Huang, Herman Batelaan

Department of Physics and Astronomy: Faculty Publications

The interference pattern in electron double-slit diffraction is a hallmark of quantum mechanics. A long-standing question for stochastic electrodynamics (SED) is whether or not it is capable of reproducing such effects, as interference is a manifestation of quantum coherence. In this study, we used excited harmonic oscillators to directly test this quantum feature in SED. We used two counter-propagating dichromatic laser pulses to promote a ground-state harmonic oscillator to a squeezed Schrödinger cat state. Upon recombination of the two well-separated wavepackets, an interference pattern emerges in the quantum probability distribution but is absent in the SED probability distribution. We thus …

Investigating The Talbot Effect In Arrays Of Optical Dipole Traps For Neutral Atom Quantum Computing, Sergio Aguayo

Physics

Quantum computers are devices that are able to perform calculations not achievable for classical computers. Although there are many methods for creating a quantum computer, using neutral atoms offers the advantage of being stable when compared to other methods. The purpose of this investigation is to explore possible optical dipole trap configurations that would be useful for implementing a quantum computer with neutral atoms. Specifically, we computationally investigate arrays of pinholes, the diffraction pattern generated by them, and the onset of the Talbot effect in these traps. We manipulate the radius of the pinholes, the number of pinholes in the …

Exploring A Practical Development Of Quantum Computing, Juliano A. Everett, Andrea N. Zambrano, Carlos Aguayza

Publications and Research

Tasked with describing a Quantum architecture (Superconducting loops), we additionally explored how the chosen architecture is used, developed, and how one could get started in understanding the way in which some quantum algorithms work with this architecture through Python and IBM's tools (Qiskit and IBM Q Experience).

Optical Detection And Storage Of Entanglement In Plasmonically Coupled Quantum-Dot Qubits, M. Otten, S.K. Gray, German Kolmakov V

Publications and Research

Recent proposals and advances in quantum simulations, quantum cryptography, and quantum communications substantially rely on quantum entanglement formation. Contrary to the conventional wisdom that dissipation destroys quantum coherence, coupling with a dissipative environment can also generate entanglement. We consider a system composed of two quantum-dot qubits coupled with a common, damped surface plasmon mode; each quantum dot is also coupled to a separate photonic cavity mode. Cavity quantum electrodynamics calculations show that upon optical excitation by a femtosecond laser pulse, entanglement of the quantum-dot excitons occurs, and the time evolution of the g(2) pair correlation function of the cavity photons …

Tip-Enhanced Nano-Optical Imaging Of Superacid Treated Bilayer Mos2-Ws2 2d Lateral Heterostructures, Amala Dixit

USF Tampa Graduate Theses and Dissertations

Nanoscale optical characterization of two-dimensional (2D) materials and heterostructures is important for the design of novel optoelectronic flexible nano-devices. Nano-optical photoluminescence (PL) and Raman imaging of bilayer 2D materials has been a challenging problem due to weak signals. The exciton-dominated light emission of two-dimensional (2D) transition metal dichalcogenide (TMDC) materials is affected by the formation of defects and doping states. Previous studies have shown that chemical treatment modifies the defect and doping states of chemical vapor deposition (CVD)-grown monolayers of MoS₂ and WS₂, which provides a promising possibility for engineering the optoelectronic properties of these 2D TMDCs. …

Optimization Of Quantum Optical Metrology Systems, Nicholas Michael Studer

LSU Doctoral Dissertations

It can be said that all of humanity's efforts can be understood as a problem of optimization. We each have a natural sense of what is ``good'' or ``bad'' and thus our actions tend towards maximizing -- or optimizing -- some notion of good and minimizing those things we perceive as bad or undesirable.

Within the sciences, the greatest form of good is knowledge. It is this pursuit of knowledge that leads to not only life-saving innovations and technology, but also to furthering our understanding of our natural world and driving our philosophical pursuits.

The principle method of obtaining knowledge …

Precision Of Parameter Estimation In Quantum Metrology, Chenglong You

LSU Doctoral Dissertations

The fundamental precision limit of an interferometer is crucial since it bounds the best possible sensitivity one could achieve using such a device. This thesis will focus on several different interferometers and try to give the ultimate precision bounds by carefully counting all the resources used in the interferometers.

The thesis begins with the basics of the quantum state of light. The fundamentals of quantum metrology are also reviewed and discussed. More specifically, the terminology of classical and quantum Cram\'er-Rao bound and classical and quantum Fisher information are introduced.

Chapter 3 discusses the conclusive precision bounds in two-mode interferometer such …

Kondo Signatures Of A Quantum Magnetic Impurity In Topological Superconductors, Rui Wang, Wei-Yi Su, Jian-Xin Zhu, Chin-Sen Ting, Hai Li, Changfeng Chen, Baigeng Wang, Xiaoqun Wang

Physics & Astronomy Faculty Research

We study the Kondo physics of a quantum magnetic impurity in two-dimensional topological superconductors (TSCs), either intrinsic or induced on the surface of a bulk topological insulator, using a numerical renormalization group technique. We show that, despite sharing the p+ip pairing symmetry, intrinsic and extrinsic TSCs host different physical processes that produce distinct Kondo signatures. Extrinsic TSCs harbor an unusual screening mechanism involving both electron and orbital degrees of freedom that produces rich and prominent Kondo phenomena, especially an intriguing pseudospin Kondo singlet state in the superconducting gap and a spatially anisotropic spin correlation. In sharp contrast, intrinsic TSCs support …

Optimization Of An Injection Locked Laser System For Cold Neutral Atom Traps, Elliot M. Lehman

Physics

Many types of quantum systems are being explored for use in quantum computers. One type of quantum system that shows promise for quantum computing is trapped neutral atoms. They have long coherence times, since they have multiple stable ground states and have minimal coupling with other atoms and their environment, and they can be trapped in arrays, making them individu- ally addressable. Once trapped, they can be initialized and operated on using laser pulses. This experiment utilizes a pinhole diffraction pattern, which can trap atoms in both bright and dark areas. To maximize trap strength, an injection-locked laser amplification system …

Control Of Light-Matter Interactions Via Nanostructured Photonic Materials, Nicholas Proscia

Dissertations, Theses, and Capstone Projects

The thesis here investigates the manipulation of light-matter interactions via nanoscale engineering of material systems. When material systems are structured on the nanoscale, their optical responses can be dramatically altered. In this thesis, this is done in two primary ways: One method is by changing the geometry of nanostructures to induce a resonant behavior with incident electromagnetic field of optical wavelengths. This allows field enhancement in highly localized areas to strengthen exotic light-matter interactions that would otherwise be too weak to measure or for practical use. In this regard, the work presented here studies a voltage produced in a metal …

Out-Of-Time-Ordered-Correlator Quasiprobabilities Robustly Witness Scrambling, José Raúl González Alonso, Nicole Yunger Halpern, Justin Dressel

Mathematics, Physics, and Computer Science Faculty Articles and Research

Out-of-time-ordered correlators (OTOCs) have received considerable recent attention as qualitative witnesses of information scrambling in many-body quantum systems. Theoretical discussions of OTOCs typically focus on closed systems, raising the question of their suitability as scrambling witnesses in realistic open systems. We demonstrate empirically that the nonclassical negativity of the quasiprobability distribution (QPD) behind the OTOC is a more sensitive witness for scrambling than the OTOC itself. Nonclassical features of the QPD evolve with timescales that are robust with respect to decoherence and are immune to false positives caused by decoherence. To reach this conclusion, we numerically simulate spinchain dynamics and …

Peculiar Optical Properties Of Bilayer Silicene Under The Influence Of External Electric And Magnetic Fields, Thi-Nga Do, Godfrey Gumbs, Po-Hsin Shih, Danhong Huang, Chih-Wei Chiu, Chia-Yun Chen, Ming-Fa Lin

Publications and Research

We conduct a comprehensive investigation of the effect of an applied electric field on the optical and magneto-optical absorption spectra for AB-bt (bottom-top) bilayer silicene. The generalized tightbinding model in conjunction with the Kubo formula is efficiently employed in the numerical calculations. The electronic and optical properties are greatly diversified by the buckled lattice structure, stacking configuration, intralayer and interlayer hopping interactions, spin-orbital couplings, as well as the electric and magnetic fields (Ez ˆz & Bz ˆz ). An electric field induces spin-split electronic states, a semiconductor-metal phase transitions and the Dirac cone formations in different valleys, leading to the …

Comparisons Of Performance Between Quantum And Classical Machine Learning, Christopher Havenstein, Damarcus Thomas, Swami Chandrasekaran

SMU Data Science Review

In this paper, we present a performance comparison of machine learning algorithms executed on traditional and quantum computers. Quantum computing has potential of achieving incredible results for certain types of problems, and we explore if it can be applied to machine learning. First, we identified quantum machine learning algorithms with reproducible code and had classical machine learning counterparts. Then, we found relevant data sets with which we tested the comparable quantum and classical machine learning algorithm's performance. We evaluated performance with algorithm execution time and accuracy. We found that quantum variational support vector machines in some cases had higher accuracy …

Modification Of Counterfactual Communication Protocols That Eliminates Weak Particle Traces, Yakir Aharonov, Lev Vaidman

Mathematics, Physics, and Computer Science Faculty Articles and Research

The possibility to communicate between spatially separated regions, without even a single photon passing between the two parties, is an amazing quantum phenomenon. The possibility of transmitting one value of a bit in such a way, the interaction-free measurement, has been known for quarter of a century. The protocols of full communication, including transmitting unknown quantum states, were proposed only a few years ago, but it was shown that in all these protocols the particle was leaving a weak trace in the transmission channel, the trace being larger than the trace left by a single particle passing through the channel. …

Hybrid Excitations In Organic-Semiconductor Materials, David W. Facemyer

Theses, Dissertations and Capstones

It has been suggested theoretically and realized experimentally that combining organic material and inorganic semiconductors in one heterostructure would result in resonant interactions between the Frenkel excitons in the organic material and the Wannier-Mott excitons in the semiconductors, leading to the formation of an exciton hybridization state. The new materials, possessing the complimentary characteristics of both exciton types, such as large exciton radius, enormous oscillator strength and room-temperature operation properties, would enhance optical nonlinearities and promise to have useful applications in both the field of Bose-Einstein condensation of polaritons and polariton lasers. In this work, we consider a strong coupling …

Quantum Isometry Group Of Deformation: A Counterexample, Debashish Goswami, Arnab Mandal

Journal Articles

We give a counterexample to show that the quantum isometry group of a deformed finite dimensional spectral triple may not be isomorphic with a deformation of the quantum isometry group of the undeformed spectral triple.

Quantized Circulation In Racetrack Atomtronic Circuits At Non-Zero Temperature, Benjamin R. Eller

College of Graduate Studies: Theses & Dissertations

We extend previous theoretical investigations of the creation of quantized circulation states by stirring Bose-Einstein condensates (BEC) confined in ``racetrack" potentials. The previous study, {\em Producing Smooth Flow in Atom Circuits by Stirring}, used the Gross-Pitaevskii equation (GPE), which is valid at $T=0$ K. Here we use a non-zero temperature model based on the Zaremba, Nikuni, Griffin (ZNG) theory to simulate stirring racetrack BECs. The two main goals of this thesis are 1) to understand the effects of temperature on the production of circulation and 2) to understand the mechanism by which the circulation is excited. We find that it …

Theoretical Studies Of The Structure And Stability Of Metal Chalcogenide Crntem (1≤N≤6, 1≤M≤8) Clusters, Fnu Sweta Prabha

Theses and Dissertations

In the presented work, first principle studies on electronic structure, stability, and magnetic properties of metal chalcogenide, Cr_nTe_m clusters have been carried out within a density functional framework using generalized gradient functions to incorporate the exchange and correlation effects. The energetic and electronic stability was investigated, and it was found that they are not always correlated as seen in the cluster Cr₆Te₈ which has smaller gap between its HOMO (Highest Occupied Molecular Orbital) and LUMO (Lowest Unoccupied Molecular Orbital) and a high electron affinity of 3.39 eV indicating lower electronic stability whereas higher fragmentation …

An Introduction To Supersymmetric Quantum Mechanics, Vincent R. Siggia

Theses and Dissertations

In this thesis, the general framework of supersymmetric quantum mechanics and the path integral approach will be presented (as well as the worked out example of the supersymmetric harmonic oscillator). Then the theory will be specialized to the case of supersymmetric quantum mechanics on Riemannian manifolds, which will start from a supersymmetric Lagrangian for the general case and the special case for S2. Afterwards, there will be a discussion on the superfield formalism. Concluding this thesis will be the Hamiltonian formalism followed by the inclusion of deforma- tions by potentials.

Electron Transport In One And Two Dimensional Materials, Samuel William Lagasse

Legacy Theses & Dissertations (2009 - 2024)

This dissertation presents theoretical and experimental studies in carbon nanotubes (CNTs), graphene, and van der Waals heterostructures. The first half of the dissertation focuses on cutting edge tight-binding-based quantum transport models which are used to study proton irradiation-induced single-event effects in carbon nanotubes [1], total ionizing dose effects in graphene [2], quantum hall effect in graded graphene p-n junctions [3], and ballistic electron focusing in graphene p-n junctions [4]. In each study, tight-binding models are developed, with heavy emphasis on tying to experimental data. Once benchmarked against experiment, properties of each system which are difficult to access in the laboratory, …