Bipartite Quantum Interactions: Entangling And Information Processing Abilities, 2018 Louisiana State University and Agricultural and Mechanical College

#### Bipartite Quantum Interactions: Entangling And Information Processing Abilities, Siddhartha Das

*LSU Doctoral Dissertations*

The aim of this thesis is to advance the theory behind quantum information processing tasks, by deriving fundamental limits on bipartite quantum interactions and dynamics. A bipartite quantum interaction corresponds to an underlying Hamiltonian that governs the physical transformation of a two-body open quantum system. Under such an interaction, the physical transformation of a bipartite quantum system is considered in the presence of a bath, which may be inaccessible to an observer. The goal is to determine entangling abilities of such arbitrary bipartite quantum interactions. Doing so provides fundamental limitations on information processing tasks, including entanglement distillation and secret key ...

Catalysis Of Stark-Tuned Interactions Between Ultracold Rydberg Atoms, 2018 Old Dominion University

#### Catalysis Of Stark-Tuned Interactions Between Ultracold Rydberg Atoms, A. L. Win, W. D. Williams, Thomas J. Carroll, C. I. Sukenik

*Physics and Astronomy Faculty Publications*

We have experimentally investigated a catalysis effect in the resonant energy transfer between ultracold 85Rb Rydberg atoms. We studied the time dependence of the process, 34p + 34p → 34s + 35s, and observed an enhancement of 34s state population when 34d state atoms are added.We have also performed numerical model simulations, which are in qualitative agreement with experiment and indicate that the enhancement arises from a redistribution of p-state atoms due to the presence of the d-state atoms.

Measuring The Practical Particle-In-A-Box: Orthorhombic Perovskite Nanocrystals, 2018 West Chester University of Pennsylvania

#### Measuring The Practical Particle-In-A-Box: Orthorhombic Perovskite Nanocrystals, Brandon Mitchell, Eric Herrmann, Junhao Lin, Leyre Gomez, Chris De Weerd, Yasufumi Fujiwara, Kazutomo Suenaga, Tom Gregorkiewicz

*Physics*

A connection between condensed matter physics and basic quantum mechanics is demonstrated as we use the fundamental 3D particle-in-a-box model to explain the optical properties of semiconductor nanocrystals, which are substantially modified due to quantum confinement. We also discuss recent advances in the imaging and measurement capabilities of transmission electron microscopy, which have made it possible to directly image single nanocrystals while simultaneously measuring their characteristic absorption energies. We introduce the basic theory of nanocrystals and derive a simplified expression to approximate the optical bandgap energy of an orthorhombic nanocrystal. CsPbBr3 perovskite nanocrystals are used to demonstrate this model due ...

Quantum And Classical Transport Of 2d Electrons In The Presence Of Long And Short Range Disorder, 2018 The Graduate Center, City University of New York

#### Quantum And Classical Transport Of 2d Electrons In The Presence Of Long And Short Range Disorder, Jesse Kanter

*All Dissertations, Theses, and Capstone Projects*

This work focuses on the study of electron transport of 2-D electron gas systems in relation to both fundamental properties of the systems such as disorder and scattering mechanisms, as well as unique magnetoresistance (MR) effects. A large portion of the discussion is built around the use of an in plane magnetic field to vary the ratio between the Zeeman energy between electrons of different spins and the Landau level spacing, creating a tool to control the quantization of the density of states (DOS).

This tool is first used to isolate Quantum Positive Magnetoresistance (QPMR), which grants insight to the ...

Charge State Dynamics And Quantum Sensing With Defects In Diamond, 2018 The Graduate Center, City University of New York

#### Charge State Dynamics And Quantum Sensing With Defects In Diamond, Jacob D. Henshaw

*All Dissertations, Theses, and Capstone Projects*

In recent years, defect centers in wide band gap semiconductors such as diamond, have received significant attention. Defects offer great utility as single photon emitters, nanoscale sensors, and quantum memories and registers for quantum computation. Critical to the utility of these defects, is their charge state.

In this dissertation, experiments surrounding the charge state dynamics and the carrier dynamics are performed and analyzed. Extensive studies of the ionization and recombination processes of defects in diamond, specifically, the Nitrogen Vacancy (NV) center, have been performed. Diffusion of ionized charge carriers has been imaged indirectly through the recapture of said carriers by ...

Topological Recursion And Random Finite Noncommutative Geometries, 2018 The University of Western Ontario

#### Topological Recursion And Random Finite Noncommutative Geometries, Shahab Azarfar

*Electronic Thesis and Dissertation Repository*

In this thesis, we investigate a model for quantum gravity on finite noncommutative spaces using the topological recursion method originated from random matrix theory. More precisely, we consider a particular type of finite noncommutative geometries, in the sense of Connes, called spectral triples of type ${(1,0)} \,$, introduced by Barrett. A random spectral triple of type ${(1,0)}$ has a fixed fermion space, and the moduli space of its Dirac operator ${D=\{ H , \cdot \} \, ,}$ ${H \in {\mathcal{H}_N}}$, encoding all the possible geometries over the fermion space, is the space of Hermitian matrices ${\mathcal{H}_N}$. A distribution of ...

Topics In Pt-Symmetric Quantum Mechanics And Classical Systems, 2018 Washington University in St. Louis

#### Topics In Pt-Symmetric Quantum Mechanics And Classical Systems, Nima Hassanpour

*Arts & Sciences Electronic Theses and Dissertations*

Space-time reflection symmetry, or PT symmetry, first proposed in quantum mechanics by Bender and Boettcher in 1998 [2], has become an active research area in fundamental physics. This dissertation contains several research problems which are more or less related to this field of study. After an introduction on complementary topics for the main projects in Chap.1, we discuss about an idea which is originated from the remarkable paper by Chandrasekar et al in Chap.2. They showed that the (second-order constant-coefficient) classical equation of motion for a damped harmonic oscillator can be derived from a Hamiltonian having one degree ...

Scattering Of Few Photon Fields By Two Level Systems In A One Dimensional Geometry, 2018 University of Arkansas, Fayetteville

#### Scattering Of Few Photon Fields By Two Level Systems In A One Dimensional Geometry, William Konyk

*Theses and Dissertations*

Recent experimental progress has realized strong, efficient coupling of effective two level systems to waveguides. We study the scattering of multimode photons from such emitters coupled losslessly to the confined geometry of a one dimensional waveguide. We develop novel techniques for describing the scattered state of both single and multi-photon wavepackets and explore how such wavepackets interact with arrays of emitters coupled to a one dimensional waveguide. Finally, we apply these techniques and analyze the capability of two particular systems to act as a quantum conditional logic gate.

Effect Of Self-Bias On Cylindrical Capacitive Discharge For Processing Of Inner Walls Of Tubular Structures-Case Of Srf Cavities, 2018 Old Dominion University

#### Effect Of Self-Bias On Cylindrical Capacitive Discharge For Processing Of Inner Walls Of Tubular Structures-Case Of Srf Cavities, J. Upadhyay, J. Peshl, S. Popović, A.-M. Valente-Feliciano, L. Vušković

*Physics Faculty Publications*

Cylindrical capacitive discharge is a convenient medium for generating reactive ions to process inner walls superconductive radio-frequency (SRF) cavities. These cavities, used in particle accelerators, presents a three-dimensional structure made of bulk Niobium, with axial cylindrical symmetry. Manufactured cavity walls are covered with Niobium oxides and scattered particulates, which must be removed for desired SRF performance. Cylindrical capacitive discharge in a mixture of Ar and Cl_{2} is a sole and natural non-wet acid choice to purify the inner surfaces of SRF cavities by reactive ion etching. Coaxial cylindrical discharge is generated between a powered inner electrode and the grounded ...

Entanglement Entropy, Dualities, And Deconfinement In Gauge Theories, 2018 Lewis and Clark College

#### Entanglement Entropy, Dualities, And Deconfinement In Gauge Theories, Mohamed M. Anber, Benjamin J. Kolligs

*Portland Institute for Computational Science Publications*

Computing the entanglement entropy in confining gauge theories is often accompanied by puzzles and ambiguities. In this work we show that compactifying the theory on a small circle S ^{1/L} evades these difficulties. In particular, we study Yang-Mills theory on R^{3}×S ^{1/L} with double-trace deformations or adjoint fermions and hold it at temperatures near the deconfinement transition. This theory is dual to a multi-component (electric-magnetic) Coulomb gas that can be mapped either to an XY-spin model with Z_{p} symmetry-preserving perturbations or dual Sine-Gordon model. The entanglement entropy of the dual SineGordon model exhibits an extremum ...

Nodal Variational Principle For Excited States, 2018 Iowa State University and Ames Laboratory

#### Nodal Variational Principle For Excited States, Federico Zahariev, Mark S. Gordon, Mel Levy

*Ames Laboratory Accepted Manuscripts*

It is proven that the exact excited-state wave function and energy may be obtained by minimizing the energy expectation value of trial wave functions that are constrained only to have the correct nodes of the state of interest. This excited-state nodal minimum principle has the advantage that it requires neither minimization with the constraint of wave-function orthogonality to all lower eigenstates nor the antisymmetry of the trial wave functions. It is also found that the minimization over the entire space can be partitioned into several interconnected minimizations within the individual nodal regions, and the exact excited-state energy may be obtained ...

Strengthening Weak Measurements Of Qubit Out-Of-Time-Order Correlators, 2018 Chapman University

#### Strengthening Weak Measurements Of Qubit Out-Of-Time-Order Correlators, Justin Dressel, José Raúl González Alonso, Mordecai Waegell, Nicole Yunger Halpern

*Mathematics, Physics, and Computer Science Faculty Articles and Research*

For systems of controllable qubits,we provide amethod for experimentally obtaining a useful class of multitime correlators using sequential generalized measurements of arbitrary strength. Specifically, if a correlator can be expressed as an average of nested (anti)commutators of operators that square to the identity, then that correlator can be determined exactly from the average of a measurement sequence. As a relevant example, we provide quantum circuits for measuring multiqubit out-of-time-order correlators using optimized control-Z or ZX-90 two-qubit gates common in superconducting transmon implementations.

What Is A Photon? Foundations Of Quantum Field Theory, 2018 Utah State University

#### What Is A Photon? Foundations Of Quantum Field Theory, Charles G. Torre

*All Physics Faculty Publications*

This is a brief, informal, and relatively low-level course on the foundations of quantum field theory. The prerequisites are undergraduate courses in quantum mechanics and electromagnetism.

Numerical And Analytical Bounds On Threshold Error Rates For Hypergraph-Product Codes, 2018 University of Nebraska - Lincoln

#### Numerical And Analytical Bounds On Threshold Error Rates For Hypergraph-Product Codes, Alexey Kovalev, Sanjay Prabhakar, Ilya Dumer, Leonid P. Pryadko

*Faculty Publications, Department of Physics and Astronomy*

We study analytically and numerically decoding properties of finite-rate hypergraph-product quantum low density parity-check codes obtained from random (3,4)-regular Gallager codes, with a simple model of independent X and Z errors. Several nontrivial lower and upper bounds for the decodable region are constructed analytically by analyzing the properties of the homological difference, equal minus the logarithm of the maximum-likelihood decoding probability for a given syndrome. Numerical results include an upper bound for the decodable region from specific heat calculations in associated Ising models and a minimum-weight decoding threshold of approximately 7%.

Electron- And Positron-Impact Ionization Of Inert Gases, 2018 Old Dominion University

#### Electron- And Positron-Impact Ionization Of Inert Gases, R. I. Campeanu, H. R. J. Walters, Colm T. Whelan

*Physics Faculty Publications*

Triple-differential cross sections (TDCS) are presented for the electron and positron impact ionization of inert gas atoms in a range of geometries where a number of significant few body effects compete to define the shape of the TDCS. Using both positrons and electrons as projectiles has opened up the possibility of performing complementary studies which could effectively isolate competing interactions which cannot be separately detected in an experiment with a single projectile. A comparison is presented between theory and the recent experiments of [Gavin, deLucio, and DuBois, Phys. Rev. A95, 062703 (2017)] for *e ^{±}* and contrasted with the results from ...

Full Dyon Excitation Spectrum In Extended Levin-Wen Models, 2018 University of Utah

#### Full Dyon Excitation Spectrum In Extended Levin-Wen Models, Yuting Hu, Nathan Geer, Yong-Shi Wu

*Mathematics and Statistics Faculty Publications*

In Levin-Wen (LW) models, a wide class of exactly solvable discrete models, for two-dimensional topological phases, it is relatively easy to describe only single-fluxon excitations, but not the charge and dyonic as well as many-fluxon excitations. To incorporate charged and dyonic excitations in (doubled) topological phases, an extension of the LW models is proposed in this paper. We first enlarge the Hilbert space with adding a tail on one of the edges of each trivalent vertex to describe the internal charge degrees of freedom at the vertex. Then, we study the full dyon spectrum of the extended LW models, including ...

Radical Social Ecology As Deep Pragmatism: A Call To The Abolition Of Systemic Dissonance And The Minimization Of Entropic Chaos, 2018 Fordham University

#### Radical Social Ecology As Deep Pragmatism: A Call To The Abolition Of Systemic Dissonance And The Minimization Of Entropic Chaos, Arielle Brender

*Student Theses 2015-Present*

This paper aims to shed light on the dissonance caused by the superimposition of Dominant Human Systems on Natural Systems. I highlight the synthetic nature of Dominant Human Systems as egoic and linguistic phenomenon manufactured by a mere portion of the human population, which renders them inherently oppressive unto peoples and landscapes whose wisdom were barred from the design process. In pursuing a radical pragmatic approach to mending the simultaneous oppression and destruction of the human being and the earth, I highlight the necessity of minimizing entropic chaos caused by excess energy expenditure, an essential feature of systems that aim ...

Vibrational Relaxation Theory For Systems Embedded In Microscopically Specified Reservoirs, 2018 University of New Mexico

#### Vibrational Relaxation Theory For Systems Embedded In Microscopically Specified Reservoirs, Anastasia Aemilia Ierides

*Physics & Astronomy ETDs*

This dissertation is a study of the theoretical framework of the practical as well as fundamental problem of the process of relaxation to equilibrium of quantum mechanical systems. The fundamental aspect is concerned with the simultaneous occurrence of decoherence and population equilibration. The practical aspect deals with experimental observations of vibrational relaxation of molecules embedded in liquids or solids. The systems include, but are not limited to, the nondegenerate dimer and harmonic oscillator, in one case weak and in the other strong, interaction with a thermal bath. The time dependence of the energy and the temperature dependence of the relaxation ...

Dispersive Quantum Interface With Atoms And Nanophotonic Waveguides, 2018 University of New Mexico

#### Dispersive Quantum Interface With Atoms And Nanophotonic Waveguides, Xiaodong Qi

*Physics & Astronomy ETDs*

Strong coupling between atoms and light is critical for quantum information processing and precise sensing. A nanophotonic waveguide is a promising platform for realizing an atom-light interface that reaches the strong coupling regime. In this dissertation, we study the dispersive response theory of the nanowaveguide system as the means to create an entangling atom-light interface, with applications to quantum non-demolition (QND) measurement and spin squeezing.

We calculate the dyadic Green's function, which determines the scattering of light by atoms in the presence of a nanowaveguide, and thus the phase shift and polarization rotation induced on the guided light. The ...

Efficient Quantum Approximation : Examining The Efficiency Of Select Universal Gate Sets In Approximating 1-Qubit Quantum Gates., 2018 University of Louisville

#### Efficient Quantum Approximation : Examining The Efficiency Of Select Universal Gate Sets In Approximating 1-Qubit Quantum Gates., Brent A. Mode

*College of Arts & Sciences Senior Honors Theses*

Quantum computation is of current ubiquitous interest in physics, computer science, and the public interest. In the not-so-distant future, quantum computers will be relatively common pieces of research equipment. Eventually, one can expect an actively quantum computer to be a common feature of life. In this work, I study the approximation efficiency of several common universal quantum gate sets at short sequence lengths using an implementation of the Solovay-Kitaev algorithm. I begin by developing from almost nothing the relevant formal mathematics to rigorously describe what one means by the terms universal gate set and covering efficiency. I then describe some ...