Nonadiabatic Multielectron Dynamics In Interaction Of Molecules With Intense Laser Pulses, 2018 University of Colorado at Boulder

#### Nonadiabatic Multielectron Dynamics In Interaction Of Molecules With Intense Laser Pulses, Andres F. Mora

*Undergraduate Honors Theses*

Ultrashort high intensity laser pulses have allowed for the observation of ultrafast dynamics in atoms and molecules. Due to the complexity, these multielectron systems interacting with ultrashort intense laser fields are often theoretically studied using the single active electron approximation (SAE). We present here results of simulations within Time Dependent Density Functional Theory which address the multielectron nature of the studied systems. The results exhibit multielectron effects in form of orbital coupling and non-adiabatic electron dynamics in electron localization, high harmonic generation and ionization of N+ 2 interacting with a strong laser pulse.

Mathematical Foundations Of Adaptive Quantum Processing, 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 ...

Emergent Phenomena In Quantum Critical Systems, 2018 University of Massachusetts Amherst

#### Emergent Phenomena In Quantum Critical Systems, Kun Chen

*Doctoral Dissertations*

A quantum critical point (QCP) is a point in the phase diagram of quantum matter where a continuous phase transition takes place at zero temperature. Low-dimensional quantum critical systems are strongly correlated, therefore hosting nontrivial emergent phenomena. In this thesis, we first address two decades-old problems on quantum critical dynamics. We then reveal two novel emergent phenomena of quantum critical impurity problems. In the first part of the thesis, we address the linear response dynamics of the $(2+1)$-dimensional $O(2)$ quantum critical universality class, which can be realized in the ultracold bosonic system near the superfluid (SF) to ...

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

Quantum Phase Transitions In Disordered Boson Systems, 2018 University of Massachusetts Amherst

#### Quantum Phase Transitions In Disordered Boson Systems, Zhiyuan Yao

*Doctoral Dissertations*

In this dissertation, we study the superfluid-insulator quantum phase transition in disordered boson systems. Recently, there has been considerable controversy over the validity of the scaling relations of the superfluid--Bose-glass quantum phase transition in three dimensions. Results from experimental and numerical studies on disordered quantum magnets contradict the scaling relations and the associated conventional scaling hypothesis for the singular part of the free energy. We determine various critical exponents of the superfluid--Bose-glass quantum phase transition in three-dimensional disordered Bose-Hubbard model through extensive Monte Carlo simulations. Our numerical study shows the previous studies on disordered quantum magnets were performed outside the ...

Selection Rules And Population Trapping In Rydberg States In Strong Field Interactions, 2018 University of Colorado, Boulder

#### Selection Rules And Population Trapping In Rydberg States In Strong Field Interactions, Zetong Xue

*Undergraduate Honors Theses*

We study the excitation to Rydberg states in the interaction of the hydrogen and helium atom with a short strong laser pulse, as it has been analyzed before for monochromatic cw lasers. Utilizing solutions of the time-dependent Schrödinger equation we have analyzed if the parity of the populated angular momentum states agrees with the selection rules for multiphoton resonant absorption. We have further investigated how the results and conclusions depend on the parameters of the laser pulse, such as intensity and pulse length. Different mechanisms to explain the distributions in the populations of the angular momentum states are tested by ...

Producing Smooth Flow In Atom Circuits By Stirring, 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 ...

Resonances From Lattice Qcd, 2018 Old Dominion University

#### Resonances From Lattice Qcd, Raúl A. Briceño

*Physics Faculty Publications*

The spectrum of hadron is mainly composed as shortly-lived states (resonance) that decay onto two or more hadrons. These resonances play an important role in a variety of phenomenologically significant processes. In this talk, I give an overview on the present status of a rigorous program for studying of resonances and their properties using lattice QCD. I explain the formalism needed for extracting resonant amplitudes from the finite-volume spectra. From these one can extract the masses and widths of resonances. I present some recent examples that illustrate the power of these ideas. I then explain similar formalism that allows for ...

Scattering Processes And Resonances From Lattice Qcd, 2018 Old Dominion University

#### Scattering Processes And Resonances From Lattice Qcd, Raúl A. Briceño, Jozef J. Dudek, Ross D. Young

*Physics Faculty Publications*

The vast majority of hadrons observed in nature are not stable under the strong interaction; rather they are resonances whose existence is deduced from enhancements in the energy dependence of scattering amplitudes. The study of hadron resonances offers a window into the workings of quantum chromodynamics (QCD) in the low-energy nonperturbative region, and in addition many probes of the limits of the electroweak sector of the standard model consider processes which feature hadron resonances. From a theoretical standpoint, this is a challenging field: the same dynamics that binds quarks and gluons into hadron resonances also controls their decay into lighter ...

Isoscalar Ππ; Kk; Ηη Scattering And The Σ; F0; F2 Mesons From Qcd, 2018 Old Dominion University

#### Isoscalar Ππ; Kk; Ηη Scattering And The Σ; F0; F2 Mesons From Qcd, Raul A. Briceño, Jozef J. Dudek, Robert G. Edwards, David J. Wilson

*Physics Faculty Publications*

We present the first lattice QCD study of coupled isoscalar *ππ*;K ¯K; *ηη* S- and D-wave scattering extracted from discrete finite-volume spectra computed on lattices which have a value of the light quark mass corresponding to m_{π} ∼ 391 MeV. In the J^{P} = 0^{+} sector we find analogues of the experimental σ and f_{0 }(980) states, where the σ appears as a stable bound-state below *ππ* threshold, and, similar to what is seen in experiment, the f_{0 }(980) manifests itself as a dip in the* ππ* cross section in the vicinity of the K ¯K threshold ...

The Participating Mind In The Quantum Universe, 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, 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 ...

Interaction-Free Effects Between Distant Atoms, 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, 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, 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, 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, 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 *B _{x}* and the strength of the next-nearest-neighbor interaction

*J*, 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 ...

_{2}Energy-Constrained Quantum Communication And Digital Dynamical Decoupling, 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, 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, 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 ...