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Parallel Algorithms For Time Dependent Density Functional Theory In Real-Space And Real-Time, James Kestyn 2018 University of Massachusetts Amherst

Parallel Algorithms For Time Dependent Density Functional Theory In Real-Space And Real-Time, James Kestyn

Doctoral Dissertations

Density functional theory (DFT) and time dependent density functional theory (TDDFT) have had great success solving for ground state and excited states properties of molecules, solids and nanostructures. However, these problems are particularly hard to scale. Both the size of the discrete system and the number of needed eigenstates increase with the number of electrons. A complete parallel framework for DFT and TDDFT calculations applied to molecules and nanostructures is presented in this dissertation. This includes the development of custom numerical algorithms for eigenvalue problems and linear systems. New functionality in the FEAST eigenvalue solver presents an additional level of ...


The Participating Mind In The Quantum Universe, Menas Kafatos, Keun-Hang Susan Yang 2018 Chapman University

The Participating Mind In The Quantum Universe, Menas Kafatos, Keun-Hang Susan Yang

Mathematics, Physics, and Computer Science Faculty Articles and Research

The Orthodox interpretation of quantum mechanics, which followed the Copenhagen Interpretation but was enhanced by primarily Werner Heisenberg and John von Neumann into a fully developed theory, brought in, among others, the role of measurement, available choices and response of the quantum system. It is, more consistent and clear than other interpretations of quantum mechanics as it provides account of the interactions of observers with the external world. As such, the Orthodox interpretation does a lot more than just account for physical interactions in the atomic world, which was the original goal of quantum mechanics in the early part of ...


Geometroneurodynamics And Neuroscience, Keun-Hang Susan Yang, Menas Kafatos 2018 Chapman University

Geometroneurodynamics And Neuroscience, Keun-Hang Susan Yang, Menas Kafatos

Mathematics, Physics, and Computer Science Faculty Articles and Research

The Orthodox Interpretation of quantum mechanics, as developed by many physicists, particularly John von Neumann, addresses the role of measurement, available choices and response of the quantum system to questions posed by an observer in specific quantum laboratory experiments. As such, it is, more consistent and clearer than other interpretations of quantum mechanics and it provides an account of the interactions of observers with the external world. However, in order to explore whether quantum mechanics plays a role in the brain, which is the primary issue, one has to examine the applicability of Hilbert space structure as a valid geometric ...


Producing Smooth Flow In Atom Circuits By Stirring, Olatunde Oladehin 2018 Georgia Southern University

Producing Smooth Flow In Atom Circuits By Stirring, Olatunde Oladehin

Electronic Theses and Dissertations

We studied how smooth flow can be produced by stirring an ultracold atom circuit consisting of a gaseous Bose--Einstein condensate (BEC) confined in a ``racetrack'' potential. The racetrack potential was made up of two straight parallel channels of length L connected on both ends by semicircular channels of the same width and (energy) depth as the straightaways. We used the Gross--Pitaevskii equation to simulate the behavior of the BEC in this potential when stirred by a rectangular paddle at various speeds and barrier heights. We found that smooth flow could be produced and conducted a systematic study of the flow ...


Resonant Anisotropic Emission In Rabbitt Spectroscopy, Bejan M. Ghomashi 2018 University of Central Florida

Resonant Anisotropic Emission In Rabbitt Spectroscopy, Bejan M. Ghomashi

Honors Undergraduate Theses

A variant of RABBITT pump-probe spectroscopy in which the attosecond pulse train comprises both even and odd harmonics of the fundamental IR probe frequency is explored to measure time-resolved photoelectron emission in systems that exhibit autoionizing states. It is shown that the group delay of both one-photon and two-photon resonant transitions is directly encoded in the energy-resolved photoelectron anisotropy as a function of the pump-probe time-delay. This principle is illustrated for a 1D model with symmetric zero-range potentials that supports both bound states and shape-resonances. The model is studied using both perturbation theory and solving the time-dependent Schodinger equation on ...


Mathematical Foundations Of Adaptive Quantum Processing, Daniel Bonior 2018 University of Central Florida

Mathematical Foundations Of Adaptive Quantum Processing, Daniel Bonior

Electronic Theses and Dissertations

Quantum information has the potential to revolutionize the way we store, process, transfer and acquire information [1,14,15,21,37]. In particular, quantum information offers exciting new approaches to secure communication, computation and sensing. However, in order to realize such technologies, we must first understand the effect that environmental noise has on a quantum system. This dissertation builds upon recent studies that have explored the underlying structure of quantum information and the effects of qubit channels in quantum communication protocols. This work is divided into five main chapters, with Chapter 1 being a brief introduction to quantum information. We ...


First-Principles Investigation Of The Interfacial Properties Of Boron Nitride, Kevin Waters 2018 Michigan Technological University

First-Principles Investigation Of The Interfacial Properties Of Boron Nitride, Kevin Waters

Dissertations, Master's Theses and Master's Reports

The interactions of nanomaterial surfaces with biological compounds, e.g. proteins, DNA, etc., unites the biological regime and nanomaterial world. Hybrid systems of boron-nitride nanotubes (BNNTs) and biological compounds are well-suited for a broad range of applications. First-principles methods are used to characterize the interface of these hybrid systems. Previous work has shown that the sensing capabilities of pristine BNNT are limited by long-ranged interactions. In this study the surfaces of pristine and functionalized BNNTs are investigated. The surfaces of the functionalized BNNTs give new properties to the tubes, which may enhance their sensing capabilities, while retaining their stability and ...


Generalizable Modeling Of Charge Transport In Single Electron Transistor Devices: Application To Thermal Sensitivity In Semiconducting Island Systems, Paniz Khanmohammadi Hazaveh 2018 Michigan Technological University

Generalizable Modeling Of Charge Transport In Single Electron Transistor Devices: Application To Thermal Sensitivity In Semiconducting Island Systems, Paniz Khanmohammadi Hazaveh

Dissertations, Master's Theses and Master's Reports

Electronic devices, especially MOSFETs, have been dimensionally scaled down to enhance operation of integrated circuits, addressing challenges such as current leakage, fluctuation of intrinsic semiconductor properties, and power dissipation. Reaching dimensions below 20 nm, there are fundamental limitations that are difficult to overcome, driving alternative device paradigms to be sought utilizing the quantum mechanical behavior of electrons. Single electron transistor (SET) devices are examples of a new generation of low-power transistors designed to transport information via single electron tunneling through one or more islands separated by tunnel junctions. Experimentally explored SET devices have shown that there are advantages to using ...


Interaction-Free Effects Between Distant Atoms, Yakir Aharonov, Eliahu Cohen, Avshalom C. Elitzur, Lee Smolin 2017 Chapman University

Interaction-Free Effects Between Distant Atoms, Yakir Aharonov, Eliahu Cohen, Avshalom C. Elitzur, Lee Smolin

Mathematics, Physics, and Computer Science Faculty Articles and Research

A Gedanken experiment is presented where an excited and a ground-state atom are positioned such that, within the former’s half-life time, they exchange a photonwith 50% probability.Ameasurement of their energy statewill therefore indicate in 50% of the cases that no photon was exchanged. Yet other measurements would reveal that, by the mere possibility of exchange, the two atoms have become entangled. Consequently, the “no exchange” result, apparently precluding entanglement, is non-locally established between the atoms by this very entanglement. This quantum-mechanical version of the ancient Liar Paradox can be realized with already existing transmission schemes, with the addition ...


Arrow Of Time For Continuous Quantum Measurement, Justin Dressel, Areeya Chantasri, Andrew N. Jordan, Alexander N. Korotkov 2017 Chapman University

Arrow Of Time For Continuous Quantum Measurement, Justin Dressel, Areeya Chantasri, Andrew N. Jordan, Alexander N. Korotkov

Mathematics, Physics, and Computer Science Faculty Articles and Research

We investigate the statistical arrow of time for a quantum system being monitored by a sequence of measurements. For a continuous qubit measurement example, we demonstrate that time-reversed evolution is always physically possible, provided that the measurement record is also negated. Despite this restoration of dynamical reversibility, a statistical arrow of time emerges, and may be quantified by the log-likelihood difference between forward and backward propagation hypotheses. We then show that such reversibility is a universal feature of nonprojective measurements, with forward or backward Janus measurement sequences that are time-reversed inverses of each other.


Mode-Sum Prescription For Vacuum Polarization In Black Hole Spacetimes In Even Dimensions, Peter Taylor, Cormac Breen 2017 Dublin City University

Mode-Sum Prescription For Vacuum Polarization In Black Hole Spacetimes In Even Dimensions, Peter Taylor, Cormac Breen

Articles

We present a mode-sum regularization prescription for computing the vacuum polarization of a scalar field in static spherically symmetric black hole spacetimes in even dimensions. This is the first general and systematic approach to regularized vacuum polarization in higher even dimensions, building upon a previous scheme we developed for odd dimensions. Things are more complicated here since the even-dimensional propagator possesses logarithmic singularities which must be regularized. However, in spite of this complication, the regularization parameters can be computed in closed form in arbitrary even dimensions and for arbitrary metric function f(r). As an explicit example of our method ...


Spin Mode Switching At The Edge Of A Quantum Hall System, Udit Khanna, Ganpathy Murthy, Sumathi Rao, Yuval Gefen 2017 Homi Bhabha National Institute, India

Spin Mode Switching At The Edge Of A Quantum Hall System, Udit Khanna, Ganpathy Murthy, Sumathi Rao, Yuval Gefen

Physics and Astronomy Faculty Publications

Quantum Hall states can be characterized by their chiral edge modes. Upon softening the edge potential, the edge has long been known to undergo spontaneous reconstruction driven by charging effects. In this Letter we demonstrate a qualitatively distinct phenomenon driven by exchange effects, in which the ordering of the edge modes at ν = 3 switches abruptly as the edge potential is made softer, while the ordering in the bulk remains intact. We demonstrate that this phenomenon is robust, and has many verifiable experimental signatures in transport.


Quantum Fidelity Approach To The Ground-State Properties Of The One-Dimensional Axial Next-Nearest-Neighbor Ising Model In A Transverse Field, Oz de Alcantara Bonfim, B. Boechat, J. Florencio 2017 University of Portland

Quantum Fidelity Approach To The Ground-State Properties Of The One-Dimensional Axial Next-Nearest-Neighbor Ising Model In A Transverse Field, Oz De Alcantara Bonfim, B. Boechat, J. Florencio

Physics Faculty Publications and Presentations

In this work we analyze the ground-state properties of the s =1/2 one-dimensional axial next-nearest-neighbor Ising model in a transverse field using the quantum fidelity approach. We numerically determined the fidelity susceptibility as a function of the transverse field Bx and the strength of the next-nearest-neighbor interaction J2, for systems of up to 24 spins. We also examine the ground-state vector with respect to the spatial ordering of the spins. The ground-state phase diagram shows ferromagnetic, floating, and ⟨2,2⟩ phases, and we predict an infinite number of modulated phases in the thermodynamic limit (L→∞). Paramagnetism only ...


Energy-Constrained Quantum Communication And Digital Dynamical Decoupling, Haoyu Qi 2017 Louisiana State University and Agricultural and Mechanical College

Energy-Constrained Quantum Communication And Digital Dynamical Decoupling, Haoyu Qi

LSU Doctoral Dissertations

This is a two-part thesis glued together by an everlasting theme in Quantum Information Science \-- to save the quantum state, or the information stored in it, from unavoidably environment-induced noise. The first part of this thesis studies the ultimate rate of reliably transmitting information, stored in quantum systems, through a noisy evolution. Specifically, we consider communication over optical links, upon which future inter-city quantum communication networks will be built. We show how to treat the infinite-dimensional bosonic system rigorously and establish the theory of energy-constrained private and quantum communication over quantum channels. Our result represents important progress in the field ...


Evolution Of Superoscillations For Schrödinger Equation In A Uniform Magnetic Field, Fabrizio Colombo, Jonathan Gantner, Daniele C. Struppa 2017 Politecnico di Milano

Evolution Of Superoscillations For Schrödinger Equation In A Uniform Magnetic Field, Fabrizio Colombo, Jonathan Gantner, Daniele C. Struppa

Mathematics, Physics, and Computer Science Faculty Articles and Research

Aharonov-Berry superoscillations are band-limited functions that oscillate faster than their fastest Fourier component. Superoscillations appear in several fields of science and technology, such as Aharonov’s weak measurement in quantum mechanics, in optics, and in signal processing. An important issue is the study of the evolution of superoscillations using the Schrödinger equation when the initial datum is a weak value. Some superoscillatory functions are not square integrable, but they are real analytic functions that can be extended to entire holomorphic functions. This fact leads to the study of the continuity of a class of convolution operators acting on suitable spaces ...


Sheaf Theoretic Formulation For Consciousness And Qualia And Relationship To The Idealism Of Non-Dual Philosophies, Menas Kafatos, Goro Kato 2017 Chapman University

Sheaf Theoretic Formulation For Consciousness And Qualia And Relationship To The Idealism Of Non-Dual Philosophies, Menas Kafatos, Goro Kato

Mathematics, Physics, and Computer Science Faculty Articles and Research

Questions about the nature of reality, whether Consciousness is the fundamental reality in the universe, and what is Consciousness itself, have no answer in systems that assume an external reality independent of Consciousness. Ultimately, the ontological foundation of such systems is the absolute division of subject and object. We advocate instead what we consider to be an approach that is in agreement with the foundation of quantum reality, which is based on Rāmānuja’s version of Vedanta philosophy and non-dual Kashmir Śaivism. Quantum mechanics opened the door to consciousness, but it cannot account for consciousness. However, the quantum measurement problem ...


The Common Invariant Subspace Problem And Tarski’S Theorem, Grzegorz Pastuszak 2017 Nicolaus Copernicus University of Toruń

The Common Invariant Subspace Problem And Tarski’S Theorem, Grzegorz Pastuszak

Electronic Journal of Linear Algebra

This article presents a computable criterion for the existence of a common invariant subspace of $n\times n$ complex matrices $A_{1}, \dots ,A_{s}$ of a fixed dimension $1\leq d\leq n$. The approach taken in the paper is model-theoretic. Namely, the criterion is based on a constructive proof of the renowned Tarski's theorem on quantifier elimination in the theory $\ACF$ of algebraically closed fields. This means that for an arbitrary formula $\varphi$ of the language of fields, a quantifier-free formula $\varphi'$ such that $\varphi\lra\varphi'$ in $\ACF$ is given explicitly. The construction of $\varphi'$ is ...


Linear Feedback Stabilization Of A Dispersively Monitored Qubit, Taylor Lee Patti, Areeya Chantasri, Luis Pedro García-Pintos, Andrew N. Jordan, Justin Dressel 2017 Chapman University

Linear Feedback Stabilization Of A Dispersively Monitored Qubit, Taylor Lee Patti, Areeya Chantasri, Luis Pedro García-Pintos, Andrew N. Jordan, Justin Dressel

Mathematics, Physics, and Computer Science Faculty Articles and Research

The state of a continuously monitored qubit evolves stochastically, exhibiting competition between coherent Hamiltonian dynamics and diffusive partial collapse dynamics that follow the measurement record. We couple these distinct types of dynamics together by linearly feeding the collected record for dispersive energy measurements directly back into a coherent Rabi drive amplitude. Such feedback turns the competition cooperative and effectively stabilizes the qubit state near a target state. We derive the conditions for obtaining such dispersive state stabilization and verify the stabilization conditions numerically.We include common experimental nonidealities, such as energy decay, environmental dephasing, detector efficiency, and feedback delay, and ...


Quantum Control Via A Genetic Algorithm Of The Field Ionization Pathway Of A Rydberg Electron, Vincent C. Gregoric, Xinyue Kang, Zhimin Cheryl Liu, Zoe A. Rowley, Thomas J. Carroll, Michael W. Noel 2017 Bryn Mawr College

Quantum Control Via A Genetic Algorithm Of The Field Ionization Pathway Of A Rydberg Electron, Vincent C. Gregoric, Xinyue Kang, Zhimin Cheryl Liu, Zoe A. Rowley, Thomas J. Carroll, Michael W. Noel

Physics and Astronomy Faculty Publications

Quantum control of the pathway along which a Rydberg electron field ionizes is experimentally and computationally demonstrated. Selective field ionization is typically done with a slowly rising electric field pulse. The (1/n*)4 scaling of the classical ionization threshold leads to a rough mapping between arrival time of the electron signal and principal quantum number of the Rydberg electron. This is complicated by the many avoided level crossings that the electron must traverse on the way to ionization, which in general leads to broadening of the time-resolved field ionization signal. In order to control the ionization pathway, thus directing ...


Improved Partial Charge Models In Siliceous Zeolites For The Simulation Of Adsorption And Identification Of Catalytic Sites, Jarod J. Wolffis 2017 University of Nevada, Las Vegas

Improved Partial Charge Models In Siliceous Zeolites For The Simulation Of Adsorption And Identification Of Catalytic Sites, Jarod J. Wolffis

UNLV Theses, Dissertations, Professional Papers, and Capstones

Utilization of computational modelling and simulation is expanding as computer processing power has increased and as new tools have been developed. This thesis focuses on efforts to improve the accuracy of simulations in aluminosilicate zeolites, an industrially important category of materials for catalysis and separations. For these sorbents, partial atomic charge represents a critical parameter in molecular mechanics simulations, determining the Coulombic non-bonding interaction. Partial charges may also be used as a measure of important physical parameters of the system such as the degree of covalency or the relative acidity of catalytic sites. We compare several common methods for predicting ...


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