Quantum Physics Commons^™

Dynamics For Discretized Gravity In The Causal Set Approach, Benjamin Pilgrim

Electronic Theses and Dissertations

Causal set theory is an approach to quantum gravity which replaces the continuous spacetime manifold with a discrete set of points and a partial order. In this work, I will focus on causal sets embeddable in two-dimensional manifolds, and define an action based on chains which in the continuum limit replicates the Einstein-Hilbert action; furthermore, I will propose a variational principle based on this action and numerically show it can distinguish nonflat manifoldlike causal sets from the most common type of nonmanifoldlike causal sets. I will then supplement this action with a boundary term similar to the Gibbons-Hawking-York boundary term …

Quantum Computing For The Quantum Curious, Ciaran Hughes, Joshua Isaacson, Anastasia Perry, Ranbel F. Sun, Jessica Turner

Open Access Books and Manuals

This open access book makes quantum computing more accessible than ever before. A fast-growing field at the intersection of physics and computer science, quantum computing promises to have revolutionary capabilities far surpassing “classical” computation. Getting a grip on the science behind the hype can be tough: at its heart lies quantum mechanics, whose enigmatic concepts can be imposing for the novice.

This classroom-tested textbook uses simple language, minimal math, and plenty of examples to explain the three key principles behind quantum computers: superposition, quantum measurement, and entanglement. It then goes on to explain how this quantum world opens up a …

Understanding The Research And Applications Of Quantum Computing, Joshua Foss

Williams Honors College, Honors Research Projects

In-Depth research of current quantum computing understanding and practices. Presentation of possible new and creative applications of quantum computing.

Exclusion Statistics For Particles With A Discrete Spectrum, Stéphane Ouvry, Alexios P. Polychronakos

Publications and Research

We formulate and study the microscopic statistical mechanics of systems of particles with exclusion statistics in a discrete one-body spectrum. The statistical mechanics of these systems can be expressed in terms of effective single-level grand partition functions obeying a generalization of the standard thermodynamic exclusion statistics equation of state. We derive explicit expressions for the thermodynamic potential in terms of microscopic cluster coefficients and show that the mean occupation numbers of levels satisfy a nesting relation involving a number of adjacent levels determined by the exclusion parameter. We apply the formalism to the harmonic Calogero model and point out a …

Calabi-Yau Products: Graded Quivers For General Toric Calabi-Yaus, Sebastián Franco, Azeem Hasan

Publications and Research

The open string sector of the topological B-model on CY (m + 2)-folds is described by m-graded quivers with superpotentials. This correspondence generalizes the connection between CY (m + 2)-folds and gauge theories on the worldvolume of D(5 − 2m)-branes for m = 0, . . . , 3 to arbitrary m. In this paper we introduce the Calabi-Yau product, a new algorithm that starting from the known quiver theories for a pair of toric CY_m+2 and CY_n+2 produces the quiver theory for a related CY_{m+n+3 …}

Equations Of State For Warm Dense Carbon From Quantum Espresso, Derek J. Schauss

Theses and Dissertations

Warm dense plasma is the matter that exists, roughly, in the range of 10,000 to 10,000,000 Kelvin and has solid-like densities, typically between 0.1 and 10 grams per centimeter. Warm dense fluids like hydrogen, helium, and carbon are believed to make up the interiors of many planets, white dwarfs, and other stars in our universe. The existence of warm dense matter (WDM) on Earth, however, is very rare, as it can only be created with high-energy sources like a nuclear explosion. In such an event, theoretical and computational models that accurately predict the response of certain materials are thus very …

Polarization Sensitive Imaging Techniques Using Quantum Entangled Qubits, Vitaly Sukharenko

Dissertations and Theses

The aim of this research is to study imaging techniques using quantum entangled qubits. These techniques extract information about the quantum state of two entangled qubits and corelate the degree of entanglement to each pixel. Imaging information of the underlying structure or material is decoded using the reconstruction of the quantum density matrix along with the calculated entanglement and concurrence levels between the two qubits. Reconstruction of a quantum state and quantum state tomography are of increasing importance in quantum information science. Quantum state tomography is used to describe entanglement of trapped ions [1] and photons [2]. Number of experiments …

Breakdown Of Universal Scaling For Nanometer-Sized Bubbles In Graphene, Renan Villarreal, Pin-Cheng Lin, Fahim Faraji, Nasim Hassani, Harsh Bana, Zviadi Zarkua, Maya N. Nair, Hung-Chieh Tsai, Manuel Auge, Felix Junge, Hans C. Hofsaess, Stefan De Gendt, Steven De Feyter, Steven Brems, E. Harriet Åhlgren, Erik C. Neyts, Lucian Covaci, FrançOis M. Peeters, Mehdi Neek-Amal, Lino M. C. Pereira

Advanced Science Research Center

We report the formation of nanobubbles on graphene with a radius of the order of 1 nm, using ultralow energy implantation of noble gas ions (He, Ne, Ar) into graphene grown on a Pt(111) surface. We show that the universal scaling of the aspect ratio, which has previously been established for larger bubbles, breaks down when the bubble radius approaches 1 nm, resulting in much larger aspect ratios. Moreover, we observe that the bubble stability and aspect ratio depend on the substrate onto which the graphene is grown (bubbles are stable for Pt but not for Cu) and trapped element. …

Topics In Quantum Quench And Entanglement, Sinong Liu

Theses and Dissertations--Physics and Astronomy

The dissertation includes two parts.

In Part I, we study non-equilibrium phenomena in various models associated with global quantum quench. It is known that local quantities, when subjected to global quantum quench across or approaching critical points, exhibit a variety of universal scaling behaviors at various quench rates. To investigate if similar scaling holds for non-local quantities, we consider the scaling behavior of circuit complexity under quantum quench across the critical massless point in Majorana fermion field theory of the one-dimensional integrable transverse field Ising model and find it obeys such scaling. To investigate if similar scaling holds for non-relativistic …

Ligand Effects On Electronic, Magnetic, And Catalytic Properties Of Clusters And Cluster Assemblies, Dinesh Bista 9288522

Theses and Dissertations

Ligands commonly protect metallic clusters against reacting with outside reactants. However, ligands can also be used to control the redox properties enabling the formation of super donors/acceptors that can donate/accept multiple electrons. This thesis focuses on how the ligands can be used to control the electronic and magnetic features of clusters and ligand stabilized cluster-based assemblies, leading to nano pn junctions with directed transport, the possibility of light-harvesting, and catalysts for cross-coupling reactions. The thesis addresses three distinct classes of clusters and their applications. The first class of cluster “metal chalcogen clusters” is the central idea of the thesis focused …

Semiclassical Backreaction On Asymptotically Anti–De Sitter Black Holes, Peter Taylor, Cormac Breen

Articles

We consider a quantum scalar field on the classical background of an asymptotically anti–de Sitter black hole and the backreaction the field’s stress-energy tensor induces on the black hole geometry. The backreaction is computed by solving the reduced-order semiclassical Einstein field equations sourced by simple analytical approximations for the renormalized expectation value of the scalar field stress-energy tensor. When the field is massless and conformally coupled, we adopt Page’s approximation to the renormalized stress-energy tensor, while for massive fields we adopt a modified version of the DeWitt-Schwinger approximation. The latter approximation must be modified so that it possesses the correct …

Energy-Dependent Π⁺Π⁺Π⁺ Scattering Amplitude From Qcd, Maxwell T. Hansen, Raúl A. Briceño, Robert G. Edwards, Christopher E. Thomas, David J. Wilson

Physics Faculty Publications

Focusing on three-pion states with maximal isospin π⁺π⁺π⁺, we present the first nonperturbative determination of an energy-dependent three-hadron scattering amplitude from first-principles QCD. The calculation combines finite-volume three-hadron energies, extracted using numerical lattice QCD, with a relativistic finite-volume formalism, required to interpret the results. To fully implement the latter, we also solve integral equations that relate an intermediate three-body K matrix to the physical three-hadron scattering amplitude. The resulting amplitude shows rich analytic structure and a complicated dependence on the two-pion invariant masses, represented here via Dalitz-like plots of the scattering rate.

Ruling Out Color Transparency In Quasielastic ¹²C(E,E'P) Up To Q² Of 14.2 (Gev/C)², D. Bhetuwal, J. Matter, H. Szumila-Vance, F. Hauenstein, C. Yero, J. Zhang, Et Al., Hall C. Collaboration

Physics Faculty Publications

Quasielastic ¹²C(e,e'p) scattering was measured at spacelike 4-momentum transfer squared Q² = 8, 9.4, 11.4, and 14.2 (GeV/c)², the highest ever achieved to date. Nuclear transparency for this reaction was extracted by comparing the measured yield to that expected from a plane-wave impulse approximation calculation without any final state interactions. The measured transparency was consistent with no Q² dependence, up to proton momenta of 8.5 GeV/c, ruling out the quantum chromodynamics effect of color transparency at the measured Q² scales in exclusive (e, e'p) reactions. These results impose strict constraints on models of color …

Neural-Network Analysis Of Parton Distribution Functions From Ioffe-Time Pseudodistributions, Luigi Del Debbio, Tommaso Giani, Joseph Karpie, Kostas Orginos, Anatoly Radyushkin, Savvas Zafeiropoulos

Physics Faculty Publications

We extract two nonsinglet nucleon Parton Distribution Functions from lattice QCD data for reduced Ioffe-time pseudodistributions. We perform such analysis within the NNPDF framework, considering data coming from different lattice ensembles and discussing in detail the treatment of the different source of systematics involved in the fit. We introduce a recipe for taking care of systematics and use it to perform our extraction of light-cone PDFs.

Photoproduction Of The F₂(1270) Meson Using The Clas Detector, Krishna P. Adhikari, Moskov J. Amaryan, Dilini Bulumulla, Mohammad Hattawy, G. Gavalian, Charles E. Hyde, Yelena Prok, J. Zhang, Et Al., Clas Collaboration

Physics Faculty Publications

The quark structure of the f₂(1270) meson has, for many years, been assumed to be a pure quark-antiquark (qq⁻) resonance with quantum numbers J^PC = 2⁺⁺. Recently, it was proposed that the f₂(1270) is a molecular state made from the attractive interaction of two 𝜌 mesons. Such a state would be expected to decay strongly to final states with charged pions due to the dominant decay 𝜌 → π⁺π^-, whereas decay to two neutral pions would likely be suppressed. Here, we measure for the first time the reaction 𝛾p …

Differential Cross Sections For Λ (1520) Using Photoproduction At Clas, K. P. Adhikari, M.J. Amaryan, G. Gavalian, M. Hattawy, Y. Prok, Et. Al., The Clas Collaboration

Physics Faculty Publications

The reaction 𝛾p → K+Λ (1520) using photoproduction data from the CLAS g12 experiment at Jefferson Lab is studied. The decay of Λ(1520) into two exclusive channels, Σπ⁺π^- and Σ^-π⁺, is studied from the detected K⁺, π⁺, and π^- particles. A good agreement is established for the Λ(1520) differential cross sections with the previous CLAS measurements. The differential cross sections as a function of center-of-mass angle are extended to higher photon energies. Newly added are the differential cross sections as a function of invariant four-momentum transfer t, …

Experimental Tests Of Qcd Scaling Laws At Large Momentum Transfer In Exclusive Light-Meson Photoproduction, Moskov J. Amaryan, William J. Briscoe, Michael G. Ryskin, Igor I. Strakovsky

Physics Faculty Publications

We evaluated CLAS Collaboration measurements for the 90^◦ meson photoproduction off the nucleon using a tagged photon beam spanning the energy interval s = 3–11 GeV². The results are compared with the “quark counting rules” predictions.

Consistency Checks For Two-Body Finite-Volume Matrix Elements: Conserved Currents And Bound States, Raúl A. Briceño, Christopher J. Monahan

Physics Faculty Publications

We present a model-independent framework to determine finite-volume corrections of matrix elements of spatially separated current-current operators. We define these matrix elements in terms of Compton-like amplitudes, i.e., amplitudes coupling single-particle states via two current insertions. We show that the infrared behavior of these matrix elements is dominated by the single-particle pole, which is approximated by the elastic form factors of the lowest-lying hadron. Therefore, given lattice data on the relevant elastic form factors, the finite-volume effects can be estimated nonperturbatively and without recourse to effective field theories. For illustration purposes, we investigate the implications of the proposed formalism for …

On-Shell Representations Of Two-Body Transition Amplitudes: Single External Current, Raúl A. Briceño, Andrew W. Jackura, Felipe G. Ortega-Gama, Keegan H. Sherman

Physics Faculty Publications

This work explores scattering amplitudes that couple two-particle systems via a single external current insertion, 2 + J → 2. Such amplitudes can provide structural information about the excited QCD spectrum. We derive an exact analytic representation for these reactions. From these amplitudes, we show how to rigorously define resonance and bound-state form factors. Furthermore, we explore the consequences of the narrow-width limit of the amplitudes as well as the role of the Ward-Takahashi identity for conserved vector currents. These results hold for any number of two-body channels with no intrinsic spin, and a current with arbitrary Lorentz structure and …

Simultaneous Monte Carlo Analysis Of Parton Densities And Fragmentation Functions, Eric Moffat, W. Melnitchouk, Ted C. Rogers, N. Sato, Jefferson Lab Angular Momentum Collaboration

Physics Faculty Publications

We perform a comprehensive new Monte Carlo analysis of high-energy lepton-lepton, lepton-hadron and hadron-hadron scattering data to simultaneously determine parton distribution functions (PDFs) in the proton and parton to hadron fragmentation functions (FFs). The analysis includes all available semi-inclusive deep-inelastic scattering and single-inclusive e⁺e⁻ annihilation data for pions, kaons and unidentified charged hadrons, which allows the flavor dependence of the fragmentation functions to be constrained. Employing a new multistep fitting strategy and more flexible parametrizations for both PDFs and FFs, we assess the impact of different datasets on sea quark densities and confirm the previously observed suppression …