Always-On Quantum Error Tracking With Continuous Parity Measurements, 2020 Chapman University

#### Always-On Quantum Error Tracking With Continuous Parity Measurements, Razieh Mohseninia, Jing Yang, Irfan Siddiqi, Andrew N. Jordan, Justin Dressel

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

We investigate quantum error correction using continuous parity measurements to correct bit-flip errors with the three-qubit code. Continuous monitoring of errors brings the benefit of a continuous stream of information, which facilitates passive error tracking in real time. It reduces overhead from the standard gate-based approach that periodically entangles and measures additional ancilla qubits. However, the noisy analog signals from continuous parity measurements mandate more complicated signal processing to interpret syndromes accurately. We analyze the performance of several practical filtering methods for continuous error correction and demonstrate that they are viable alternatives to the standard ancilla-based approach. As an optimal ...

The Gauge Principle From The Schrodinger-Born Wave Mechanics, 2020 Portland State University

#### The Gauge Principle From The Schrodinger-Born Wave Mechanics, P. T. Leung

*Physics Faculty Publications and Presentations*

We propose an elementary way of introducing the gauge principle to beginners with a background in only mechanics, electromagnetism, and quantum mechanics. This evolves from an apparent conflict in the Schrodinger-Born formulation of wave mechanics, and does not have to resort to advanced concepts like covariant derivative and minimal coupling. With such an approach, one would have appreciated how interactions can be dictated from consideration of internal symmetry of a physical system, which serves as a principle underlying the foundation of almost all modern physics. In addition, the gauge principle also serves as a resource providing consistency between the Born ...

Emulating Condensed Matter Systems In Classical Wave Metamaterials, 2020 The Graduate Center, City University of New York

#### Emulating Condensed Matter Systems In Classical Wave Metamaterials, Matthew Weiner

*Dissertations, Theses, and Capstone Projects*

One of the best tools we have for the edification of physics is the analogy. When we take our classical set of states and dynamical variables in phase space and treat them as vectors and Hermitian operators respectively in Hilbert space through the canonical quantization, we lose out on a lot of the intuition developed with the previous classical physics. With classical physics, through our own experiences and understanding of how systems should behave, we create easy-to-understand analogies: we compare the Bohr model of the atom to the motion of the planets, we compare electrical circuits to the flow of ...

Machine Learning Corrected Quantum Dynamics Calculations, 2020 Penn State University

#### Machine Learning Corrected Quantum Dynamics Calculations, A. Jasinski, J. Montaner, R. C. Forrey, B. H. Yang, P. C. Stancil, Naduvalath Balakrishnan, J. Dai, A. Vargas-Hernandez, R. V. Krems

*Chemistry and Biochemistry Faculty Publications*

Quantum scattering calculations for all but low-dimensional systems at low energies must rely on approximations. All approximations introduce errors. The impact of these errors is often difficult to assess because they depend on the Hamiltonian parameters and the particular observable under study. Here, we illustrate a general, system- and approximation-independent, approach to improve the accuracy of quantum dynamics approximations. The method is based on a Bayesian machine learning (BML) algorithm that is trained by a small number of exact results and a large number of approximate calculations, resulting in ML models that can generalize exact quantum results to different dynamical ...

H-Atom Ladder Operator Revisited, 2020 University of Connecticut

#### H-Atom Ladder Operator Revisited, Carl W. David

*Chemistry Education Materials*

An error laden note (Am. J. Phys., 34, 984,(1966)) concerning the ladder operator solution to the hydrogen atom electronic energy levels is corrected.

Qwasi: The Quantum Walk Simulator, 2020 CUNY Hunter College

#### Qwasi: The Quantum Walk Simulator, Warren V. Wilson

*School of Arts & Sciences Theses*

As quantum computing continues to evolve, the ability to design and analyze novel quantum algorithms becomes a necessary focus for research. In many instances, the virtues of quantum algorithms only become evident when compared to their classical counterparts, so a study of the former often begins with a consideration of the latter. This is very much the case with quantum walk algorithms, as the success of random walks and their many, varied applications have inspired much interest in quantum correlates. Unfortunately, finding purely algebraic solutions for quantum walks is an elusive endeavor. At best, and when solvable, they require simple ...

Contact In The Unitary Fermi Gas Across The Superfluid Phase Transition, 2020 Yale University

#### Contact In The Unitary Fermi Gas Across The Superfluid Phase Transition, S. Jensen, Christopher N. Gilbreth, Y. Alhassid

*All Faculty Scholarship for the College of the Sciences*

A quantity known as the contact is a fundamental thermodynamic property of quantum many-body systems with short-range interactions. Determination of the temperature dependence of the contact for the unitary Fermi gas of infinite scattering length has been a major challenge, with different calculations yielding qualitatively different results. Here we use finite-temperature auxiliary-field quantum Monte Carlo (AFMC) methods on the lattice within the canonical ensemble to calculate the temperature dependence of the contact for the homogeneous spin-balanced unitary Fermi gas. We extrapolate to the continuum limit for 40, 66, and 114 particles, eliminating systematic errors due to finite-range effects. We observe ...

Noncontextuality Inequalities From Antidistinguishability, 2020 Chapman University

#### Noncontextuality Inequalities From Antidistinguishability, Matthew S. Leifer, Cristhiano Duarte

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

Noncontextuality inequalities are usually derived from the distinguishability properties of quantum states, i.e., their orthogonality. Here, we show that *antidistinguishability* can also be used to derive noncontextuality inequalities. The Yu-Oh 13-ray noncontextuality inequality can be rederived and generalized as an instance of our antidistinguishability method. For some sets of states, the antidistinguishability method gives tighter bounds on noncontextual models than just considering orthogonality, and the Hadamard states provide an example of this. We also derive noncontextuality inequalities based on mutually unbiased bases and symmetric informationally complete positive operator-valued measures. Antidistinguishability based inequalities were initially discovered as overlap bounds for ...

Non-Adiabatic Quantum Dynamics Of The Ultracold Li+Lina→ Li2+Na Chemical Reaction, 2020 Los Alamos National Laboratory

#### Non-Adiabatic Quantum Dynamics Of The Ultracold Li+Lina→ Li2+Na Chemical Reaction, B. K. Kendrick, M. Li, H. Li, S. Kotochigova, J. F.E. Croft, Balakrishnan Naduvalath

*Chemistry and Biochemistry Faculty Publications*

We report non-adiabatic dynamics of the Li+LiNa→Li2+Na chemical reaction at cold and ultracold temperatures employing accurate ab initio electronic potential energy surfaces in a quantum dynamics formulation employing a diabatic representation. Results are compared against those from a single adiabatic ground state potential energy surface and a universal model based on the long-range interaction potential. We discuss signatures of non-universal behavior in the total rate coefficients as well as strong non-adiabatic effects in the state-to-state rotationally resolved rate coefficients.

Quantum Random Walk Search And Grover's Algorithm - An Introduction And Neutral-Atom Approach, 2020 California Polytechnic State University, San Luis Obispo

#### Quantum Random Walk Search And Grover's Algorithm - An Introduction And Neutral-Atom Approach, Anna Maria Houk

*Physics*

In the sub-field of quantum algorithms, physicists and computer scientist take classical computing algorithms and principles and see if there is a more efficient or faster approach implementable on a quantum computer, i.e. a ”quantum advantage”. We take random walks, a widely applicable group of classical algorithms, and move them into the quantum computing paradigm. Additionally, an introduction to a popular quantum search algorithm called Grover’s search is included to guide the reader to the development of a quantum search algorithm using quantum random walks. To close the gap between algorithm and hardware, we will look at using ...

At The Interface Of Algebra And Statistics, 2020 The Graduate Center, City University of New York

#### At The Interface Of Algebra And Statistics, Tai-Danae Bradley

*Dissertations, Theses, and Capstone Projects*

This thesis takes inspiration from quantum physics to investigate mathematical structure that lies at the interface of algebra and statistics. The starting point is a passage from classical probability theory to quantum probability theory. The quantum version of a probability distribution is a density operator, the quantum version of marginalizing is an operation called the partial trace, and the quantum version of a marginal probability distribution is a reduced density operator. Every joint probability distribution on a finite set can be modeled as a rank one density operator. By applying the partial trace, we obtain reduced density operators whose diagonals ...

Generating Entanglement With The Dynamical Lamb Effect, 2020 The Graduate Center, City University of New York

#### Generating Entanglement With The Dynamical Lamb Effect, Mirko Amico

*Dissertations, Theses, and Capstone Projects*

According to quantum field theory, the vacuum is filled with virtual particles which can be turned into real ones under the influence of external perturbations. Phenomena of this kind are commonly referred to as quantum vacuum phenomena. Several quantum vacuum phenomena related to the peculiar nature of the quantum vacuum have been predicted, some of which, such as the Lamb shift and the Casimir effect, have been experimentally found. Other examples of quantum vacuum phenomena include the Unruh effect, the dynamical Casimir effect and the dynamical Lamb effect. The dynamical Lamb effect was first predicted by considering the situation of ...

Small-X Qcd Calculations With A Biased Ensemble, 2020 The Graduate Center, City University of New York

#### Small-X Qcd Calculations With A Biased Ensemble, Gary Kapilevich

*Dissertations, Theses, and Capstone Projects*

In this dissertation, I will argue that we can study functional fluctuations in unintegrated gluon distributions, in the MV model as well as JIMWLK, using reweighting techniques, which will allow me to calculate QCD observables with "biased ensembles". This technique will enable me to study rare functional configurations of the gluon distributions, that might have been selected for in, for example, the centrality criteria used by the ATLAS and ALICE collaborations. After a review of these techniques, as well as a review of QCD physics at high energy in general, I will use biased ensembles to compute observables in two ...

Measurement, Dissipation, And Quantum Control With Superconducting Circuits, 2020 Washington University in St. Louis

#### Measurement, Dissipation, And Quantum Control With Superconducting Circuits, Patrick Harrington

*Arts & Sciences Electronic Theses and Dissertations*

The interaction between a superconducting circuit and its environment can cause decoherence. However, interactions with an environment are necessary for quantum state preparation and measurement. Through the dynamics of open quantum systems, the environment is a resource to control and readout superconducting circuit states. I present an experimental result demonstrating qubit state stabilization from engineered dissipation with a microwave photonic crystal. In addition, I discuss the statistical arrow of time in the dynamics of continuous quantum measurement. These results demonstrate an interplay between open quantum system dynamics and statistics, which highlights the role of both dissipation and measurement for quantum ...

Density Functional Theory Calculations Of Al Doped Hafnia For Different Crystal Symmetry Configurations, 2020 Seton Hall University

#### Density Functional Theory Calculations Of Al Doped Hafnia For Different Crystal Symmetry Configurations, Joshua Steier

*Seton Hall University Dissertations and Theses (ETDs)*

Dogan et al.[1], investigated the causes of ferroelectricity in doped hafnia using ab initio methods. Similarly, we investigated the stability of Al doped hafnia using quantum mechanical methods.

There are many different phases of Hafnia: monoclinic, tetragonal, cubic and orthorhombic. Starting with the monoclinic phase of Hafnia, Hafnia undergoes phase transitions which result in different space groups. The temperature at which the tetragonal phase is induced is 2000 K and cubic phase is induced at 2900 K[1]. Different dielectric constants vary from phase to phase. The average dielectric constants are highest for the cubic and tetragonal phases. In ...

A Study Of Optical Nonlinearities At The Single-Photon Level For Quantum Logic, 2020 University of Arkansas, Fayetteville

#### A Study Of Optical Nonlinearities At The Single-Photon Level For Quantum Logic, Balakrishnan Viswanathan

*Theses and Dissertations*

In this dissertation, we shall focus on theoretically studying quantum nonlinear optical schemes to construct a conditional phase gate at the single-photon level. With an aim to develop analytical models, we shall carry out a rigorous quantized multimode field analysis of some of these schemes involving only the interacting field operators. More specifically, we shall first study the three-wave mixing process involving two single-photons in a second-order nonlinear medium (x(2)) under two different cases viz. when the photons are traveling with equal velocities and when they are traveling with different velocities, and explore the possibility of using them for ...

An Overview Of Lasers And Their Applications, 2020 California Polytechnic State University, San Luis Obispo

#### An Overview Of Lasers And Their Applications, Luis Cristian Giovanni Guerrero

*Physics*

This paper is an overview of lasers and their applications. The fundamentals of laser operation are covered as well as the various applications of advanced laser systems. The primary focus is to highlight some of the technological advancements made possible by lasers in the last half-century.

Two-Outcome Synchronous Correlation Sets And Connes' Embedding Problem, 2020 Army Cyber Institute

#### Two-Outcome Synchronous Correlation Sets And Connes' Embedding Problem, Travis Russell

*West Point Research Papers*

We show that Connes' embedding problem is equivalent to the weak Tsirelson problem in the setting of two-outcome synchronous correlation sets. We further show that the extreme points of two-outcome synchronous correlation sets can be realized using a certain class of universal C*-algebras. We examine these algebras in the three-experiment case and verify that the strong and weak Tsirelson problems have affirmative answers in that setting.

Conservation Of Orbital Angular Momentum In Degenerate Four-Wave Mixing Via Rubidium Vapor, 2020 William & Mary

#### Conservation Of Orbital Angular Momentum In Degenerate Four-Wave Mixing Via Rubidium Vapor, Kangning Yang

*Undergraduate Honors Theses*

We present an experimental platform which can generate quantum-correlated beams with Orbital Angular Momentum (OAM) via degenerate Four-Wave Mixing (FWM) in Rubidium vapor. We further investigated the conservation of OAM before and after FWM by performing LG mode decomposition using interferometer. To compare our experimental result with theoretical prediction, we simulated a simplified version of our set up. Moreover, we used this toy model to study the conservation of radial and angular intensity profile through changing parameters limited by our set up. In general, we found that FWM preserves most information consisted in OAM, but has a rather loose control ...

Studies In Seop Hyperpolarized 3he: Measuring Ko And The Spatial Dependence Of Alkali Polarization, 2020 William & Mary

#### Studies In Seop Hyperpolarized 3he: Measuring Ko And The Spatial Dependence Of Alkali Polarization, Michael Cairo

*Undergraduate Honors Theses*

^{3}He is an isotope of helium whose nucleus is composed of two protons and one neutron. The proportion of atoms whose spins are pointed along the same direction in a volume of ^{3}He gas is known as the polarization. This study entails two experiments in the field of ^{3}He polarimetry concerned with measuring the polarization of a ^{3}He cell and reducing the uncertainty associated with it. ^{3}He cells are full of gaseous ^{3}He, along with alkali metal vapors, K and Rb in our case. The polarization of a ^{3}He cell can be measured ...