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 ...

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.

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 ...

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 ...

Two-Mode Squeezing And Conservation Of Optical Angular Momentum Via Four-Wave Mixing In Rubidium, 2018 College of William and Mary

#### Two-Mode Squeezing And Conservation Of Optical Angular Momentum Via Four-Wave Mixing In Rubidium, Nathan Super

*Undergraduate Honors Theses*

The goal of the project is to produce a pair of intensity-squeezed light fields using Four-Wave Mixing (FWM) in hot Rubidium vapor. In this process, interaction of atoms with near-resonant strong control optical field results in strong amplification of a weak probe optical field and in generation of a quantum correlated conjugate Stokes optical field. In order to establish the quantum correlation between the Stokes and probe fields, we measured the differential intensity noise between the Stokes and probe fields. If the noise falls below the quantum noise limit, then two-mode intensity squeezing has been achieved, as a first step ...

Power Corrections To Tmd Factorization For Z-Boson Production, 2018 Old Dominion University

#### Power Corrections To Tmd Factorization For Z-Boson Production, I. Balitsky, A. Tatasov

*Physics Faculty Publications*

A typical factorization formula for production of a particle with a small transverse momentum in hadron-hadron collisions is given by a convolution of two TMD parton densities with cross section of production of the final particle by the two partons. For practical applications at a given transverse momentum, though, one should estimate at what momenta the power corrections to the TMD factorization formula become essential. In this paper we calculate the first power corrections to TMD factorization formula for Z-boson production and Drell-Yan process in high-energy hadron-hadron collisions. At the leading order in *N*_{c} power corrections are expressed in ...

Finding Paths Via Quantum Systems And Its Application For Quantum Algorithms, 2018 The Graduate Center, City University of New York

#### Finding Paths Via Quantum Systems And Its Application For Quantum Algorithms, Daniel S. Koch

*All Dissertations, Theses, and Capstone Projects*

The field of Quantum Information Theory provides the theoretical foundation for the pursuit of quantum computers. The ongoing questions of how quantum computers will be realized and what they will achieve, are both very uncertain. However, worldwide efforts are beginning to converge on some answers, and the future of quantum computers is looking brighter than ever. In contribution to the grand goal that is quantum computing, this thesis serves as a demonstration to the usefulness of quantum over classical computing. The central theme of my work, and my collaborators, is the exploration of using quantum systems as a tool for ...

N-Representability In The Quantum Kernel Energy Method, 2018 The Graduate Center, City University of New York

#### N-Representability In The Quantum Kernel Energy Method, Walter Polkosnik

*All Dissertations, Theses, and Capstone Projects*

The Kernel Energy Method (KEM) delivers accurate full molecule energies using less computational resources than standard ab-initio quantum chemical approaches. KEM achieves this efficiency by decomposing a system of atoms into disjoint subsets called kernels. The results of full ab-initio calculations on each individual single kernel and on each double kernel formed by the union of each pair of single kernels are combined in an equation of a form that is specific to KEM to provide an approximation to the full molecule energy. KEM has been demonstrated to give accurate molecular energies over a wide range of systems, chemical methods ...

Primordial Black Hole Atoms, 2018 Rowan University

#### Primordial Black Hole Atoms, David Zwick, Tyler Hanover, Brian Nepper

*Student Research Symposium Posters*

Primordial black holes are thought to have been formed at the early stages of the universe in the presence of non-homogeneous density distributions of dark matter. We are working under the assumption that dark matter consists of elementary low mass particles, specifically, spin 1/2 fermions. We further assume that dark matter is electrically neutral, thus its main interaction is gravitational. We investigate dark matter spin 1/2 fermions in orbit around a black hole atom and consider mass ranges for which the quantum description is appropriate. Solutions to the Dirac equation are utilized to describe the radial mass distribution ...

Quasiprobability Behind The Out-Of-Time-Ordered Correlator, 2018 California Institute of Technology

#### Quasiprobability Behind The Out-Of-Time-Ordered Correlator, Nicole Yunger Halpern, Brian Swingle, Justin Dressel

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

Two topics, evolving rapidly in separate fields, were combined recently: the out-of-time-ordered correlator (OTOC) signals quantum-information scrambling in many-body systems. The Kirkwood-Dirac (KD) quasiprobability represents operators in quantum optics. The OTOC was shown to equal a moment of a summed quasiprobability [Yunger Halpern, Phys. Rev. A 95, 012120 (2017)]. That quasiprobability, we argue, is an extension of the KD distribution. We explore the quasiprobability's structure from experimental, numerical, and theoretical perspectives. First, we simplify and analyze Yunger Halpern's weak-measurement and interference protocols for measuring the OTOC and its quasiprobability. We decrease, exponentially in system size, the number of ...

Extreme Field Sensitivity Of Magnetic Tunneling In Fe-Doped Li3n, 2018 University of Augsburg

#### Extreme Field Sensitivity Of Magnetic Tunneling In Fe-Doped Li3n, M. Fix, J. H. Atkinson, Paul C. Canfield, E. Del Barco, A. Jesche

*Ames Laboratory Accepted Manuscripts*

The magnetic properties of dilute Li-2(Li1-xFex)N with x similar to 0.001 are dominated by the spin of single, isolated Fe atoms. Below T = 10 K the spin-relaxation times become temperature independent indicating a crossover from thermal excitations to the quantum tunneling regime. We report on a strong increase of the spin-flip probability in transverse magnetic fields that proves the resonant character of this tunneling process. Longitudinal fields, on the other hand, lift the ground-state degeneracy and destroy the tunneling condition. An increase of the relaxation time by 4 orders of magnitude in applied fields of only a ...

Entropic Bounds On Two-Way Assisted Secret-Key Agreement Capacities Of Quantum Channels, 2018 Louisiana State University and Agricultural and Mechanical College

#### Entropic Bounds On Two-Way Assisted Secret-Key Agreement Capacities Of Quantum Channels, Noah Anthony Davis

*LSU Doctoral Dissertations*

In order to efficiently put quantum technologies into action, we must know the characteristics of the underlying quantum systems and effects. An interesting example is the use of the secret-key-agreement capacity of a quantum channel as a guide and measure for the implementation of quantum key distribution (QKD) and distributed quantum computation. We define the communication task of establishing a secret key over a quantum channel subject to an energy constraint on the input state and while allowing for unlimited local operations and classical communication (LOCC) between a sender and receiver. We then use the energy-constrained squashed entanglement to bound ...

Characterization Of Polymers Containing Ferrocene And Imidazole With Density Functional Theory, 2018 Pittsburg State University

#### Characterization Of Polymers Containing Ferrocene And Imidazole With Density Functional Theory, Eric Mullins

*Electronic Thesis Collection*

Electrochemical and UV-Vis studies on these polymers in the presence of aqueous solutions containing metal ions have revealed significant modifications in the electrochemical properties and absorption spectra. These modifications in electrochemical properties could be attributed to the ability of the imidazole to coordinate with metal ions, increasing its electron deficiency and enhancing oxidization of the nearby ferrocene moiety if it is in close proximity with imidazole. However, the mechanism of interaction between the imidazole and metal ions, as well as the equilibrium geometry of the resulting polymer-metal ion complex is unknown.

In this thesis, density functional theory (DFT) was used ...