Improving The State Selectivity Of Field Ionization With Quantum Control, 2018 Bryn Mawr College

#### Improving The State Selectivity Of Field Ionization With Quantum Control, Vincent C. Gregoric, Jason Bennett, Bianca R. Gualtieri, Ankitha Kannad, Zhimin Cheryl Liu, Zoe A. Rowley, Thomas J. Carroll, Michael W. Noel

*Physics and Astronomy Faculty Publications*

The electron signals from the field ionization of two closely spaced Rydberg states of rubidium-85 are separated using quantum control. In selective field ionization, the state distribution of a collection of Rydberg atoms is measured by ionizing the atoms with a ramped electric field. Generally, atoms in higher energy states ionize at lower fields, so ionized electrons which are detected earlier in time can be correlated with higher energy Rydberg states. However, the resolution of this technique is limited by the Stark effect. As the electric field is increased, the electron encounters numerous avoided Stark level crossings which split the ...

Sampling Complexity Of Bosonic Random Walkers On A One-Dimensional Lattice, 2018 University of New Mexico - Main Campus

#### Sampling Complexity Of Bosonic Random Walkers On A One-Dimensional Lattice, Gopikrishnan Muraleedharan, Akimasa Miyake, Ivan Deutsch

*Shared Knowledge Conference*

Computers based quantum logic are believed to solve problems faster and more efficiently than computers based on classical boolean logic. However, a large-scale universal quantum computer with error correction may not be realized in near future. But we can ask the question: can we devise a specific problem that a quantum device can solve faster than current state of the art super computers? One such problem is the so called "Boson Sampling" problem introduced by Aaronson and Arkhipov. The problem is to generate random numbers according to same distribution as the output number configurations of photons in linear optics. It ...

Plasmon-Enhanced Quadrupolar Transitions With Nanostructured Graphene, 2018 University of New Mexico

#### Plasmon-Enhanced Quadrupolar Transitions With Nanostructured Graphene, Stephen Sanders

*Shared Knowledge Conference*

Many important molecules have quadrupolar excitations which occur at much slower rates than the competing dipolar transitions and hence are termed forbidden. In this work, we propose a new approach to enhance quadrupolar transitions using graphene nanostructures. We provide a detailed investigation of the enhanced transition rate in the vicinity of graphene nanoislands and use rigorous computational methods to analyze how this quantity changes with the geometrical and material parameters of the nanoisland. To support these calculations we also provide a semi-analytic approach. Finally, we investigate the performance of arrays of graphene nanoribbons, which constitutes a suitable platform for the ...

The Weak Reality That Makes Quantum Phenomena More Natural: Novel Insights And Experiments, 2018 Chapman University

#### The Weak Reality That Makes Quantum Phenomena More Natural: Novel Insights And Experiments, Yakir Aharonov, Eliahu Cohen, Mordecai Waegell, Avshalom C. Elitzur

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

While quantum reality can be probed through measurements, the Two-State Vector Formalism (TSVF) reveals a subtler reality prevailing between measurements. Under special pre- and post-selections, odd physical values emerge. This unusual picture calls for a deeper study. Instead of the common, wave-based picture of quantum mechanics, we suggest a new, particle-based perspective: Each particle possesses a definite location throughout its evolution, while some of its physical variables (characterized by deterministic operators, some of which obey nonlocal equations of motion) are carried by “mirage particles” accounting for its unique behavior. Within the time interval between pre- and post-selection, the particle gives ...

Beam Theory For Classical And Quantum Nonlinear Optics---Exposing Classical And Quantum Correlations Of Transverse-Spatial Modes, 2018 Department of Physics and Astronomy

#### Beam Theory For Classical And Quantum Nonlinear Optics---Exposing Classical And Quantum Correlations Of Transverse-Spatial Modes, Robert Nicholas Lanning

*LSU Doctoral Dissertations*

Optics is arguably the most important branch of physics that has ever been studied. It is not only an essential ingredient of many other branches of physics that we study, it governs how we see, how we measure, and how we communicate in the modern world. And as the world continues to change, so do our tools and resources. In a relatively short amount of time, we have progressed from rudimentary tools that shape the world around us, to tools that harness the fundamental laws of nature. Unsurprisingly, the laws of nature governing optics remain paramount. This is because many ...

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 ...

Current-Driven Production Of Vortex-Antivortex Pairs In Planar Josephson Junction Arrays And Phase Cracks In Long-Range Order, 2018 Old Dominion University

#### Current-Driven Production Of Vortex-Antivortex Pairs In Planar Josephson Junction Arrays And Phase Cracks In Long-Range Order, Francisco Estellés-Duart, Miguel Ortuño, Andrés M. Somoza, Valerii M. Vinokur, Alex Gurevich

*Physics Faculty Publications*

Proliferation of topological defects like vortices and dislocations plays a key role in the physics of systems with long-range order, particularly, superconductivity and superfluidity in thin films, plasticity of solids, and melting of atomic monolayers. Topological defects are characterized by their topological charge reflecting fundamental symmetries and conservation laws of the system. Conservation of topological charge manifests itself in extreme stability of static topological defects because destruction of a single defect requires overcoming a huge energy barrier proportional to the system size. However, the stability of driven topological defects remains largely unexplored. Here we address this issue and investigate numerically ...

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 ...

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, T. J. Carroll, C. I. Sukenik

*Physics Faculty Publications*

We have experimentally investigated a catalysis effect in the resonant energy transfer between ultracold ^{85}Rb Rydberg atoms. We studied the time dependence of the process, 34*p* + 34*p* → 34*s* + 35*s*, 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.

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 ...

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 ...

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.

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.