Quantum Information Science Activities at NSF
Total Page：16
File Type：pdf, Size：1020Kb
Load more
Recommended publications
-
![3-Fermion Topological Quantum Computation [1]](https://docslib.b-cdn.net/cover/3170/3-fermion-topological-quantum-computation-1-33170.webp)
3-Fermion Topological Quantum Computation [1]
3-Fermion topological quantum computation [1] Sam Roberts1 and Dominic J. Williamson2 1Centre for Engineered Quantum Systems, School of Physics, The University of Sydney, Sydney, NSW 2006, Australia 2Stanford Institute for Theoretical Physics, Stanford University, Stanford, CA 94305, USA I. INTRODUCTION Topological quantum computation (TQC) is currently the most promising approach to scalable, fault-tolerant quantum computation. In recent years, the focus has been on TQC with Kitaev's toric code [2], due to it's high threshold to noise [3, 4], and amenability to planar architectures with nearest neighbour interactions. To encode and manipulate quantum information in the toric code, a variety of techniques drawn from condensed matter contexts have been utilised. In particular, some of the efficient approaches for TQC with the toric code rely on creating and manipulating gapped-boundaries, symmetry defects and anyons of the underlying topological phase of matter [5{ 10]. Despite great advances, the overheads for universal fault-tolerant quantum computation remain a formidable challenge. It is therefore important to analyse the potential of TQC in a broad range of topological phases of matter, and attempt to find new computational substrates that require fewer quantum resources to execute fault-tolerant quantum computation. In this work we present an approach to TQC for more general anyon theories based on the Walker{Wang mod- els [11]. This provides a rich class of spin-lattice models in three-dimensions whose boundaries can naturally be used to topologically encode quantum information. The two-dimensional boundary phases of Walker{Wang models accommodate a richer set of possibilities than stand-alone two-dimensional topological phases realized by commuting projector codes [12, 13]. -
Does the Family Cap Influence Birthrates? Two New Studies Say 'No'
Issues & Implications Cash Increase No ‘Incentive’ The New Jersey and the Arkansas Does the Family Cap studies raise serious questions about the validity of family cap propo- Influence Birthrates? nents’ primary rationale for the policy—the notion that an increase Two New Studies Say ‘No’ in monthly benefits upon the birth of a new baby acts as an incentive By Patricia Donovan for welfare recipients to have more children. When the Arkansas Contrary to early claims that a cap on when the researchers controlled for researchers asked a subsample of benefits would reduce birthrates the age and race of the nearly 8,500 the women studied whether they among welfare recipients, recent stud- women studied. would have another child in order to ies in New Jersey and Arkansas con- receive higher benefits, fully 100% of clude that denying an increase in The researchers also examined state those subject to the cap and more cash assistance to women who have Medicaid data to assess whether the than 95% of those in the control another child while on welfare has family cap had any impact on abor- group said they would not. Many did had no effect on births in these states. tion rates among women on welfare. not know how much more money Some antiabortion advocates have they would receive if they had In response to the findings, New feared that a cap could result in more another child. Jersey officials now insist that the abortions among welfare recipients, family cap was never intended to but the analysis indicates otherwise. “It appears that women do not make reduce births, but simply to encour- Like birthrates, abortion rates in New decisions about the birth of their age welfare recipients to make Jersey declined both among women children based on the addition of responsible decisions about child- subject to the cap and among the $42 per month in…benefits,” the bearing. -
![Arxiv:1705.01740V1 [Cond-Mat.Str-El] 4 May 2017 2](https://docslib.b-cdn.net/cover/8269/arxiv-1705-01740v1-cond-mat-str-el-4-may-2017-2-178269.webp)
Arxiv:1705.01740V1 [Cond-Mat.Str-El] 4 May 2017 2
Physics of the Kitaev model: fractionalization, dynamical correlations, and material connections M. Hermanns1, I. Kimchi2, J. Knolle3 1Institute for Theoretical Physics, University of Cologne, 50937 Cologne, Germany 2Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA and 3T.C.M. group, Cavendish Laboratory, J. J. Thomson Avenue, Cambridge, CB3 0HE, United Kingdom Quantum spin liquids have fascinated condensed matter physicists for decades because of their unusual properties such as spin fractionalization and long-range entanglement. Unlike conventional symmetry breaking the topological order underlying quantum spin liquids is hard to detect exper- imentally. Even theoretical models are scarce for which the ground state is established to be a quantum spin liquid. The Kitaev honeycomb model and its generalizations to other tri-coordinated lattices are chief counterexamples | they are exactly solvable, harbor a variety of quantum spin liquid phases, and are also relevant for certain transition metal compounds including the polymorphs of (Na,Li)2IrO3 Iridates and RuCl3. In this review, we give an overview of the rich physics of the Kitaev model, including 2D and 3D fractionalization as well as dynamical correlations and behavior at finite temperatures. We discuss the different materials, and argue how the Kitaev model physics can be relevant even though most materials show magnetic ordering at low temperatures. arXiv:1705.01740v1 [cond-mat.str-el] 4 May 2017 2 CONTENTS I. Introduction 2 II. Kitaev quantum spin liquids 3 A. The Kitaev model 3 B. Classifying Kitaev quantum spin liquids by projective symmetries 4 C. Confinement and finite temperature 5 III. Symmetry and chemistry of the Kitaev exchange 6 IV. -
Kitaev Materials
Kitaev Materials Simon Trebst Institute for Theoretical Physics University of Cologne, 50937 Cologne, Germany Contents 1 Spin-orbit entangled Mott insulators 2 1.1 Bond-directional interactions . 4 1.2 Kitaev model . 6 2 Honeycomb Kitaev materials 9 2.1 Na2IrO3 ...................................... 9 2.2 ↵-Li2IrO3 ..................................... 10 2.3 ↵-RuCl3 ...................................... 11 3 Triangular Kitaev materials 15 3.1 Ba3IrxTi3 xO9 ................................... 15 − 3.2 Other materials . 17 4 Three-dimensional Kitaev materials 17 4.1 Conceptual overview . 18 4.2 β-Li2IrO3 and γ-Li2IrO3 ............................. 22 4.3 Other materials . 23 5 Outlook 24 arXiv:1701.07056v1 [cond-mat.str-el] 24 Jan 2017 Lecture Notes of the 48th IFF Spring School “Topological Matter – Topological Insulators, Skyrmions and Majoranas” (Forschungszentrum Julich,¨ 2017). All rights reserved. 2 Simon Trebst 1 Spin-orbit entangled Mott insulators Transition-metal oxides with partially filled 4d and 5d shells exhibit an intricate interplay of electronic, spin, and orbital degrees of freedom arising from a largely accidental balance of electronic correlations, spin-orbit entanglement, and crystal-field effects [1]. With different ma- terials exhibiting slight tilts towards one of the three effects, a remarkably broad variety of novel forms of quantum matter can be explored. On the theoretical side, topology is found to play a crucial role in these systems – an observation which, in the weakly correlated regime, has lead to the discovery of the topological band insulator [2, 3] and subsequently its metallic cousin, the Weyl semi-metal [4, 5]. Upon increasing electronic correlations, Mott insulators with unusual local moments such as spin-orbit entangled degrees of freedom can form and whose collective behavior gives rise to unconventional types of magnetism including the formation of quadrupo- lar correlations or the emergence of so-called spin liquid states. -
Jane Alexandria Smith
[email protected] Bellandra B. Foster, Ph.D., P.E. Phone: 336.355.7897 QUALIFICATIONS SUMMARY Years of Experience Licensed professional engineer and program manager with extensive civil and 31 construction engineering experience. Manager and administrator of numerous projects within public agencies and private industry and as Founder and President of an engineering corporation. Professional Registrations EDUCATION Licensed Professional Engineer: Doctor of Philosophy, Civil Engineering State of Georgia Michigan State University – December 1999 State of Illinois Traffic and Transportation Engineering Seminar State of Michigan Northwestern University – June 1999 State of No. Carolina Certification - Transportation Systems (ITS) State of Ohio University of Michigan - September 1992 Master of Science Degree, Civil Engineering Professional Wayne State University – May 1989 Certifications Bachelor of Science Degree, Civil Engineering U.S. Small Business Michigan State University – August 1983 Administration Emerging 200 (E200) CIVIL AND CONSTRUCTION ENGINEERING EXPERIENCE Class of 2011 BBFoster Consulting, P.C. (8/2014-Present) President– BBFoster Consulting, PC provides civil engineering, program management, Level 1 Erosion and Sedimentation Control coaching, contract administration, utility coordination and compliance assistance. Inspector BBF ENGINEERING SERVICES, P.C. (4/94-12/2014) President and Principal Engineer – Founder and Owner of BBF Engineering Services, Professional P.C. The company provided civil engineering, project -
Some Comments on Physical Mathematics
Preprint typeset in JHEP style - HYPER VERSION Some Comments on Physical Mathematics Gregory W. Moore Abstract: These are some thoughts that accompany a talk delivered at the APS Savannah meeting, April 5, 2014. I have serious doubts about whether I deserve to be awarded the 2014 Heineman Prize. Nevertheless, I thank the APS and the selection committee for their recognition of the work I have been involved in, as well as the Heineman Foundation for its continued support of Mathematical Physics. Above all, I thank my many excellent collaborators and teachers for making possible my participation in some very rewarding scientific research. 1 I have been asked to give a talk in this prize session, and so I will use the occasion to say a few words about Mathematical Physics, and its relation to the sub-discipline of Physical Mathematics. I will also comment on how some of the work mentioned in the citation illuminates this emergent field. I will begin by framing the remarks in a much broader historical and philosophical context. I hasten to add that I am neither a historian nor a philosopher of science, as will become immediately obvious to any expert, but my impression is that if we look back to the modern era of science then major figures such as Galileo, Kepler, Leibniz, and New- ton were neither physicists nor mathematicans. Rather they were Natural Philosophers. Even around the turn of the 19th century the same could still be said of Bernoulli, Euler, Lagrange, and Hamilton. But a real divide between Mathematics and Physics began to open up in the 19th century. -
Science Fiction on American Television
TV Sci-Fi 16 + GUIDE This and other bfi National Library 16 + Guides are available from http://www.bfi.org.uk/16+ TV Sci-Fi CONTENTS Page IMPORTANT NOTE................................................................................................................. 1 ACCESSING RESEARCH MATERIALS.................................................................................. 2 APPROACHES TO RESEARCH, by Samantha Bakhurst ....................................................... 4 INTRODUCTION by Sean Delaney ......................................................................................... 6 AMERICAN TELEVISION........................................................................................................ 8 SCIENCE FICTION ON AMERICAN TELEVISION ................................................................. 9 AUDIENCES AND FANS......................................................................................................... 11 ANDROMEDA ......................................................................................................................... 12 BABYLON 5 ............................................................................................................................ 14 BATTLESTAR GALACTICA................................................................................................... 17 FARSCAPE ............................................................................................................................. 19 THE IRWIN ALLEN QUARTET • VOYAGE TO THE BOTTOM OF THE SEA..................................................................... -
A Quantum Leap for AI
TRENDS & CONTROVERSIES A quantum leap for AI By Haym Hirsh Rutgers University [email protected] November 1994 saw the near-simultaneous publication of two papers that threw the notion of computing on its head. On November 11, 1994, a paper by Leonard Adleman appeared in Science demonstrating that a vial of DNA fragments can serve as a computer for solving instances of the Hamiltonian path problem. Less than two weeks later, Peter Shor Quantum computing and AI presented a paper in Santa Fe, New Mexico, at the 35th Annual Symposium on Foundations Subhash Kak, Louisiana State University of Computer Science, demonstrating how a quantum computer could be used to factor large Every few years, we hear of a new tech- numbers in a tractable fashion. Both these publications showed how nontraditional models nology that will revolutionize AI. After of computation had the potential to effectively solve problems previously believed to be careful reflection, we find that the advance intractable under traditional models of computation. However, the latter work, using a quan- is within the framework of the Turing tum model of computation proposed by Richard Feynmann and others in the early 1980s, machine model and equivalent, in many resonated well with AI researchers who had been coming to terms with Roger Penrose’s cases, to existing statistical techniques. But 1989 book The Emperor’s New Mind. In this book (and its sequel, Shadows of the Mind: A this time, in quantum computing, we seem Search for the Missing Science of Consciousness, which appeared in paperback form only a to be on the threshold of a real revolution— month before these papers), Penrose challenges the possibility of achieving AI via traditional a “quantum” leap—because it is a true “Turing-equivalent” computation devices, conjecturing that the roots of intelligence can be frontier beyond classical computing. -
Alexei Kitaev, Annals of Physics 321 2-111
Annals of Physics 321 (2006) 2–111 www.elsevier.com/locate/aop Anyons in an exactly solved model and beyond Alexei Kitaev * California Institute of Technology, Pasadena, CA 91125, USA Received 21 October 2005; accepted 25 October 2005 Abstract A spin-1/2 system on a honeycomb lattice is studied.The interactions between nearest neighbors are of XX, YY or ZZ type, depending on the direction of the link; different types of interactions may differ in strength.The model is solved exactly by a reduction to free fermions in a static Z2 gauge field.A phase diagram in the parameter space is obtained.One of the phases has an energy gap and carries excitations that are Abelian anyons.The other phase is gapless, but acquires a gap in the presence of magnetic field.In the latter case excitations are non-Abelian anyons whose braiding rules coincide with those of conformal blocks for the Ising model.We also consider a general theory of free fermions with a gapped spectrum, which is characterized by a spectral Chern number m.The Abelian and non-Abelian phases of the original model correspond to m = 0 and m = ±1, respectively. The anyonic properties of excitation depend on m mod 16, whereas m itself governs edge thermal transport.The paper also provides mathematical background on anyons as well as an elementary theory of Chern number for quasidiagonal matrices. Ó 2005 Elsevier Inc. All rights reserved. 1. Comments to the contents: what is this paper about? Certainly, the main result of the paper is an exact solution of a particular two-dimen- sional quantum model.However, I was sitting on that result for too long, trying to perfect it, derive some properties of the model, and put them into a more general framework.Thus many ramifications have come along.Some of them stem from the desire to avoid the use of conformal field theory, which is more relevant to edge excitations rather than the bulk * Fax: +1 626 5682764. -
Vortices and Other Topological Solitons in Dense Quark Matter
Preprint number: XXXX-XXXX Vortices and Other Topological Solitons in Dense Quark Matter Minoru Eto1, Yuji Hirono2;3;4, Muneto Nitta5y, and Shigehiro Yasui6 z 1Department of Physics, Yamagata University, Kojirakawa 1-4-12, Yamagata, Yamagata 990-8560, Japan 2Department of Physics, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan 3Theoretical Research Division, Nishina Center, RIKEN, Wako 351-0198, Japan 4Department of Physics, Sophia University, Tokyo 102-8554, Japan 5Department of Physics, and Research and Education Center for Natural Sciences, Keio University, Hiyoshi 4-1-1, Yokohama, Kanagawa 223-8521, Japan 6KEK Theory Center, Institute of Particle and Nuclear Studies, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki 305-0801, Japan ∗E-mail: [email protected] ............................................................................... Dense quantum chromodynamic matter accommodates various kind of topological solitons such as vortices, domain walls, monopoles, kinks, boojums and so on. In this review, we discuss various properties of topological solitons in dense quantum chro- modynamics (QCD) and their phenomenological implications. A particular emphasis is placed on the topological solitons in the color-flavor-locked (CFL) phase, which exhibits both superfluidity and superconductivity. The properties of topological solitons are dis- cussed in terms of effective field theories such as the Ginzburg-Landau theory, the chiral Lagrangian, or the Bogoliubov{de Gennes equation. The most fundamental string-like topological excitations in the CFL phase are the non-Abelian vortices, which are 1/3 quantized superfluid vortices and color magnetic flux tubes. These vortices are created at a phase transition by the Kibble-Zurek mechanism or when the CFL phase is realized in compact stars, which rotate rapidly. -
Black Holes and Entanglement Entropy
Black holes and entanglement entropy Thesis by Pouria Dadras In Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy in Physics CALIFORNIA INSTITUTE OF TECHNOLOGY Pasadena, California 2021 Defended May 18, 2021 ii © 2021 Pouria Dadras ORCID: 0000-0002-5077-3533 All rights reserved iii ACKNOWLEDGEMENTS First and foremost, I am truly indebted to my advisor, Alexei Kitaev, for many reasons: providing an atmosphere in which my only concern was doing research, teaching me how to deal with a hard problem, how to breaking it into small parts and solving each, many helpful suggestions and discussions tht we had in the past five years that I was his students, sharing some of his ideas and notes with me, ··· . I am also grateful to the other members of the Committee, Sean Carroll, Anton Kapustin, and David Simmons-Duffin for joining my talk, and also John Preskill for joining my Candidacy exam and having discussions. I am also grateful to my parents in Iran who generously supported me during the time that I have been in the United states. I am also Thankful to my friends, Saeed, Peyman, Omid, Fariborz, Ehsan, Aryan, Pooya, Parham, Sharareh, Pegah, Christina, Pengfei, Yingfei, Josephine, and others. iv ABSTRACT We study the deformation of the thermofield-double ¹TFDº under evolution by a double-traced operator by computing its entanglement entropy. After saturation, the entanglement change leads to the temperature change. In Jackiw-Teitelboim gravity, the new temperature can be computed independently from two- point function by considering the Schwarzian modes. We will also derive the entanglement entropy from the Casimir associated with the SL(2,R) symmetry. -
Operator Growth Bounds in a Cartoon Matrix Model
Operator growth bounds in a cartoon matrix model Andrew Lucas1, ∗ and Andrew Osborne1, y 1Department of Physics and Center for Theory of Quantum Matter, University of Colorado, Boulder CO 80309, USA (Dated: July 15, 2020) We study operator growth in a model of N(N − 1)=2 interacting Majorana fermions, which live on the edges of a complete graph of N vertices. Terms in the Hamiltonian are proportional to the product of q fermions which live on the edges of cycles of length q. This model is a cartoon \matrix model": the interaction graph mimics that of a single-trace matrix model, which can be holographically dual to quantum gravity. We prove (non-perturbatively in 1=N, and without averaging over any ensemble) that the scrambling time of this model is at least of order log N, consistent with the fast scrambling conjecture. We comment on apparent similarities and differences between operator growth in our \matrix model" and in the melonic models. CONTENTS 1. Introduction 1 2. Summary of results 2 3. Mathematical preliminaries 3 3.1. Sets and graphs 3 3.2. Majorana fermions and operator size4 3.3. The cartoon matrix model 5 3.4. Time evolution as a quantum walk7 3.5. Bound on the Lyapunov exponent8 4. Operator growth in the Majorana matrix model9 4.1. Bounding operator growth rates 9 4.2. Comparison to the Sachdev-Ye-Kitaev model 15 Acknowledgements 16 References 16 1. INTRODUCTION Our best hint to the unification of gravity with quantum mechanics arises from the holographic principle [1,2]. Some quantum mechanical systems in D spacetime dimensions, with a large N number of degrees of freedom \per site" (e.g.