Geometry Of The Set Of Synchronous Quantum Correlation Sets, 2020 Army Cyber Institute

#### Geometry Of The Set Of Synchronous Quantum Correlation Sets, Travis Russell

*West Point Research Papers*

We provide a complete geometric description of the set of synchronous quantum correlations for the three-experiment two-outcome scenario. We show that these correlations form a closed set. Moreover, every correlation in this set can be realized using projection valued measures on a Hilbert space of dimension no more than 16.

On Quantum Effects Of Vector Potentials And Generalizations Of Functional Analysis, 2020 Chapman University

#### On Quantum Effects Of Vector Potentials And Generalizations Of Functional Analysis, Ismael L. Paiva

*Computational and Data Sciences (PhD) Dissertations*

This is a dissertation in two parts. In the first one, the Aharonov-Bohm effect is investigated. It is shown that solenoids (or flux lines) can be seen as barriers for quantum charges. In particular, a charge can be trapped in a sector of a long cavity by two flux lines. Also, grids of flux lines can approximate the force associated with continuous two-dimensional distributions of magnetic fields. More, if it is assumed that the lines can be as close to each other as desirable, it is explained how the classical magnetic force can emerge from the Aharonov-Bohm effect. Continuing, the ...

Quantum Computing And Quantum Algorithms, 2020 Liberty University

#### Quantum Computing And Quantum Algorithms, Daniel Serban

*Senior Honors Theses*

The field of quantum computing and quantum algorithms is studied from the ground up. Qubits and their quantum-mechanical properties are discussed, followed by how they are transformed by quantum gates. From there, quantum algorithms are explored as well as the use of high-level quantum programming languages to implement them. One quantum algorithm is selected to be implemented in the Qiskit quantum programming language. The validity and success of the resulting computation is proven with matrix multiplication of the qubits and quantum gates involved.

Magnetic Forces In The Absence Of A Classical Magnetic Field, 2020 Chapman University

#### Magnetic Forces In The Absence Of A Classical Magnetic Field, Ismael L. Paiva, Yakir Aharonov, Jeff Tollaksen, Mordecai Waegell

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

It is shown that, in some cases, the effect of discrete distributions of flux lines in quantum mechanics can be associated with the effect of continuous distributions of magnetic fields with special symmetries. In particular, flux lines with an arbitrary value of magnetic flux can be used to create energetic barriers, which can be used to confine quantum systems in specially designed configurations. This generalizes a previous work where such energy barriers arose from flux lines with half-integer fluxons. Furthermore, it is shown how the Landau levels can be obtained from a two-dimensional grid of flux lines. These results suggest ...

On Characterizing Quantum Processes And Detectors, 2020 Louisiana State University and Agricultural and Mechanical College

#### On Characterizing Quantum Processes And Detectors, Kevin Valson Jacob

*LSU Doctoral Dissertations*

In 2009, physicists at the National Institute of Standards and Technology in Colorado, Boulder developed what could arguable be called the first rudimentary quantum computer [1]. The past decade has seen unprecedented improvements in quantum information science culminating in the demonstration of quantum supremacy --- that quantum computers can solve problems that are impractical to be solved on the best supercomputers [2]. This remarkable progress necessitates the development of techniques to characterize the quantum devices that are being developed. In my thesis, I will focus on such devices that manipulate and detect light.

In Chapter 1, I will introduce the reader ...

Limitations On Protecting Information Against Quantum Adversaries, 2020 Louisiana State University

#### Limitations On Protecting Information Against Quantum Adversaries, Eneet Kaur

*LSU Doctoral Dissertations*

The aim of this thesis is to understand the fundamental limitations on secret key distillation in various settings of quantum key distribution. We first consider quantum steering, which is a resource for one-sided device-independent quantum key distribution. We introduce a conditional mutual information based quantifier for quantum steering, which we call intrinsic steerability. Next, we consider quantum non-locality, which is a resource for device-independent quantum key distribution. In this context, we introduce a quantifier, intrinsic non-locality, which is a monotone in the resource theory of Bell non-locality. Both these quantities are inspired by intrinsic information and squashed entanglement and are ...

On The Number Of The Discrete Spectrum Of Two-Particle Discrete Schröodinger Operators, 2020 National University of Uzbekistan

#### On The Number Of The Discrete Spectrum Of Two-Particle Discrete Schröodinger Operators, Zahriddin Muminov, Utkir Kuljanov, Shukhrat Alladustov

*Bulletin of National University of Uzbekistan: Mathematics and Natural Sciences*

We consider a family of discrete Schrö dinger operators *h ^{d}(k)*, where

*k*is the two-particle quasi-momentum varying in 𝕋

^{d}=(−π,π]

*, associated to a system of two-particles on the*

^{d}*d*- dimensional lattice ℤ

^{d},

*d*>1. The CwikelLieb-Rozenblum (CLR)-type estimates are written for

*h*when the Fermi surface

^{d}(k)*E*(𝔢

_{k}^{-1}_{m}(k)) of the associated dispersion relation is a one point set at em(k), the bottom of the essential spectrum. Moreover, when the Fermi surface

*E*(𝔢

_{k}^{-1}_{m}(k)) is of dimension

*d−1*or

*d−2*, we ...

On Negative Eigenvalues Of The Discrete Schrödinger Operator With Non-Local Potential, 2020 National University of Uzbekistan

#### On Negative Eigenvalues Of The Discrete Schrödinger Operator With Non-Local Potential, Zahriddin Muminov, Shukhrat Lakaev

*Bulletin of National University of Uzbekistan: Mathematics and Natural Sciences*

On the d-dimensional lattice 𝕋^{d}, *d*= 1, 2 the discrete Schrödinger operator *H*_{λµ} with non-local potential constructed via the Dirac delta function and shift operator is considered. The dependency of negative eigenvalues of the operator on the parameters is explicitly derived.

Footprints Of Quantum Pigeons, 2020 Tel-Aviv University

#### Footprints Of Quantum Pigeons, Gregory Reznick, Shrobona Bagchi, Justin Dressel, Lev Vaidman

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

We show that in the mathematical framework of the quantum theory, the classical pigeonhole principle can be violated more directly than previously suggested, i.e., in a setting closer to the traditional statement of the principle. We describe how the counterfactual reasoning of the paradox may be operationally grounded in the analysis of the tiny footprints left in the environment by the pigeons. After identifying the drawbacks of recent experiments of the quantum pigeonhole effect, we argue that a definitive experimental violation of the pigeonhole principle is still needed and propose such an implementation using modern quantum computing hardware: a ...

Atomic Magnetometry For The Detection Of Cardio-Magnetic Fields, 2020 William & Mary

#### Atomic Magnetometry For The Detection Of Cardio-Magnetic Fields, Alexander Fay

*Undergraduate Honors Theses*

We demonstrate a method of measuring small constant gradients on top of a large constant background magnetic field using Electromagnetically Induced Transparency (EIT). The Earth provides a constant magnetic field of 25-50 μT, and as such, measuring much smaller magnetic fields as well as smaller gradients presents a challenge often requiring special shielding. We show that by making use of common mode noise subtraction from a dual rail setup, our measurement is insensitive to these large fields, and in theory our method does not require shielding. Our dual rail setup allows us to measure small magnetic field gradients by utilizing ...

The Breakup Of A Helium Cluster After Removing Attractive Interaction Among A Significant Number Of Atoms In The Cluster, 2020 University of Nevada, Las Vegas

#### The Breakup Of A Helium Cluster After Removing Attractive Interaction Among A Significant Number Of Atoms In The Cluster, Tao Pang

*Physics & Astronomy Faculty Publications*

The breakup of a quantum liquid droplet is examined through a 4He cluster by removing the attractive tail in the interaction between some of the atoms in the system with the diffusion quantum Monte Carlo simulation. The ground-state energy, kinetic energy, cluster size, and density profile of the cluster are evaluated against the percentage of the atoms without the attractive tail. The condition for the cluster to lose its ability to form a quantum liquid droplet at zero temperature is found and analyzed. The cluster is no longer able to form a quantum liquid droplet when about two-thirds of pairs ...

Novel Photon-Detector Models For Enhanced Quantum Information Processing, 2020 Louisiana State University

#### Novel Photon-Detector Models For Enhanced Quantum Information Processing, Elisha Siddiqui

*LSU Doctoral Dissertations*

This work is devoted to the development of novel photon-detector models at room temperature using quantum optics elements. This work comprises of two photon-number-resolving detector (PNRD) models, and the application of PNRD in LIDAR. The first model is based on using a two-mode squeezing device to resolve photon number at room temperature. In this model we study the average intensity-intensity correlations signal at the output of a two-mode squeezing device with |N> and |α> as the two input modes. We show that the input photon-number can be resolved from the average intensity-intensity correlations. In particular, we show jumps in the ...

Solving Combinatorial Optimization Problems Using The Quantum Approximation Optimization Algorithm, 2020 Air Force Institute of Technology

#### Solving Combinatorial Optimization Problems Using The Quantum Approximation Optimization Algorithm, Nicholas J. Guerrero

*Theses and Dissertations*

The Quantum Approximation Optimization Algorithm (QAOA) is one of the most promising applications for noisy intermediate-scale quantum machines due to the low number of qubits required as well as the relatively low gate count. Much work has been done on QAOA regarding algorithm implementation and development; less has been done checking how these algorithms actually perform on a real quantum computer. Using the IBM Q Network, several instances of combinatorial optimization problems (the max cut problem and dominating set problem) were implemented into QAOA and analyzed. It was found that only the smallest toy max cut algorithms performed adequately: those ...

Non-Heisenberg Magnetism In A Quaternary Spin-Gapless Semiconductor, 2020 Indian Institute of Technology, Mandi

#### Non-Heisenberg Magnetism In A Quaternary Spin-Gapless Semiconductor, R. Choudhary, A. Kashyap, Durga Paudyal, D. J. Sellmyer, R. Skomski

*Ames Laboratory Accepted Manuscripts*

Understanding of spin-gapless semiconductors with fully spin-polarized charge carriers is critically important because of their promise for spintronic applications. Here, we report non-collinear spin structures, magnetic ground state, and effective exchange interactions of the spin-gapless semiconductor CoFeCrAl investigated with noncollinear density functional calculations. The ground state of CoFeCrAl is ferrimagnetic and has a spin configuration with ↓ Fe, ↑ Co and ↑ Cr spins. In our constrained calculations, the magnetizations of the Fe, Co, and Cr sublattices are rotated by various angles θ, which give rise to three sets of noncollinear spin structures. For all three elements, the magnetic energy increases with the ...

Density Functional Theory Study Of Two-Dimensional Boron Nitride Films, 2020 The Graduate Center, City University of New York

#### Density Functional Theory Study Of Two-Dimensional Boron Nitride Films, Pradip R. Niraula

*Dissertations, Theses, and Capstone Projects*

Since graphene was isolated in 2004, the number of two-dimensional (2D) materials and their scientific relevance have grown exponentially. Besides graphene, one of the most important and technolocially promizing 2D materials that has emerged in recent years is hexagonal boron nitride, in its monolayer or multilayer form. In my thesis work, I used density functional theory (DFT) calculations to investigate the properties of boron nitride films. In particular, I first studied the properties (i.e. formation energy, defect states, and structure) of point charged defects in monolayer and bilayer hexagonal boron nitride, and subsequently, I focused on the linear and ...

Duality In A Model Of Layered Superfluids And Sliding Phases, 2020 The Graduate Center, City University of New York

#### Duality In A Model Of Layered Superfluids And Sliding Phases, Steven Vayl

*Dissertations, Theses, and Capstone Projects*

The intent of my project is to determine if the proposal of sliding phases in XY layered systems has physical ground. It will be done by comparing numerical and analytical results for a layered XY models. Sliding phases were first proposed in the context of DNA complexes and then extended to XY models, 1D coupled wires and superfluid films. The existence of the sliding phase would mean that there is a phase transition from 3D to 2D behavior. Such systems have been studied both in the clean case and with disorder. The idea of the sliding phases is based on ...

Luminescence Emission In A Nanocrystal Doped By A Transition Metal Impurity, 2020 Marshall University

#### Luminescence Emission In A Nanocrystal Doped By A Transition Metal Impurity, George Chappell Jr.

*Theses, Dissertations and Capstones*

In this thesis we consider the structure of magnetic ion centers with 3*d*-electrons in quantum dots under the effects of Coulomb and exchange interaction between the 3*d*-electrons of the impurity centers and the confined electrons (or holes) existing inside the nanocrystals. In particular, we are interested how this interaction changes the photoluminescence properties of those materials. We will make use of representation theory and the symmetry of the crystal structure to find the orthonormal wave functions that make up the wave functions of the outer, 3*d*-electrons inside our dot. The Coulomb and exchange interaction ...

Density Functional Calculations On Single Molecular (1d) And Van Der Waals Bi -Layered (2d) Magnets., 2020 University of Texas at El Paso

#### Density Functional Calculations On Single Molecular (1d) And Van Der Waals Bi -Layered (2d) Magnets., Md Shamsul Alam

*Open Access Theses & Dissertations*

Low-dimensional magnetic materials show novel properties that is not seen in bulk magnets. The weak interactions such as spin-orbit interactions, electron correlation, van der Waals interaction in case magnetic bi-layers, play an important role in determining the properties of the system. Using density functional theory, we computationally investigated two categories of magnetic material- 1: Single Molecular Magnets (SMM) 2: Van der Waals layered Cr-Halide magnets. We used different classes of density functionals to examine the spin ordering and magnetic anisotropy barriers in several single molecule magnets - Mn12, Co4, Ni4, V15. We find that the magnetic anisotropy barrier significantly depends on ...

Some Fermi-Lowdin Orbital Self-Interaction Correction Studies On Atomic Systems, 2020 University of Texas at El Paso

#### Some Fermi-Lowdin Orbital Self-Interaction Correction Studies On Atomic Systems, Christopher Alexis Ibarra

*Open Access Theses & Dissertations*

Density Function Theory (DFT) is a popular quantum chemistry calculation method with many appeals but also deficiencies. Many modification and additions to the method have been made over the years, such as self-interaction corrections and new density functional approximations. We review here the theoretical background needed for a basic understanding of quantum chemistry calculations. In addition, we present the quantum chemistry calculation method used in this paper called Fermi-Lowdin Self-Interaction Correction (FLOSIC), including the base code it was implemented on, the Naval Research Laboratory Molecular Orbital Library (NRLMOL) Code, and the resulting modified code simply called FLOSIC. Furthermore, we explore ...

Development And Assesment Of Local Scaled Self-Interaction Corrected Density Functional Method With Simple Scaling Factor, 2020 University of Texas at El Paso

#### Development And Assesment Of Local Scaled Self-Interaction Corrected Density Functional Method With Simple Scaling Factor, Selim Romero

*Open Access Theses & Dissertations*

The Hohenberg-Kohn-Sham (HKS) density functional theory (DFT) is widely used to compute electronic structures of atoms, molecules, and solids. It is an exact theory in which ground state electron density plays the role of basic variable, same as the wavefunction does in quantum mechanics. The total ground state energy is a functional of electron density. The practical application of HKS DFT require approximation to the exchange-correlation energy functional. Many density functional approximations (DFAs) with various degree of sophistication and complexities have been developed. Depending on the complexity, these functionals include electron density, density gradients, density Laplacian, kinetic energy densities, Hartree-Fock ...