Manipulating Frequency-Entangled Photons Laurent Olislager
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Quantum Computing a New Paradigm in Science and Technology
Quantum computing a new paradigm in science and technology Part Ib: Quantum computing. General documentary. A stroll in an incompletely explored and known world.1 Dumitru Dragoş Cioclov 3. Quantum Computer and its Architecture It is fair to assert that the exact mechanism of quantum entanglement is, nowadays explained on the base of elusive A quantum computer is a machine conceived to use quantum conjectures, already evoked in the previous sections, but mechanics effects to perform computation and simulation this state-of- art it has not impeded to illuminate ideas and of behavior of matter, in the context of natural or man-made imaginative experiments in quantum information theory. On this interactions. The drive of the quantum computers are the line, is worth to mention the teleportation concept/effect, deeply implemented quantum algorithms. Although large scale general- purpose quantum computers do not exist in a sense of classical involved in modern cryptography, prone to transmit quantum digital electronic computers, the theory of quantum computers information, accurately, in principle, over very large distances. and associated algorithms has been studied intensely in the last Summarizing, quantum effects, like interference and three decades. entanglement, obviously involve three states, assessable by The basic logic unit in contemporary computers is a bit. It is zero, one and both indices, similarly like a numerical base the fundamental unit of information, quantified, digitally, by the two (see, e.g. West Jacob (2003). These features, at quantum, numbers 0 or 1. In this format bits are implemented in computers level prompted the basic idea underlying the hole quantum (hardware), by a physic effect generated by a macroscopic computation paradigm. -
A Non-Technical Explanation of the Bell Inequality Eliminated by EPR Analysis Eliminated by Bell A
Ghostly action at a distance: a non-technical explanation of the Bell inequality Mark G. Alford Physics Department, Washington University, Saint Louis, MO 63130, USA (Dated: 16 Jan 2016) We give a simple non-mathematical explanation of Bell's inequality. Using the inequality, we show how the results of Einstein-Podolsky-Rosen (EPR) experiments violate the principle of strong locality, also known as local causality. This indicates, given some reasonable-sounding assumptions, that some sort of faster-than-light influence is present in nature. We discuss the implications, emphasizing the relationship between EPR and the Principle of Relativity, the distinction between causal influences and signals, and the tension between EPR and determinism. I. INTRODUCTION II. OVERVIEW To make it clear how EPR experiments falsify the prin- The recent announcement of a \loophole-free" observa- ciple of strong locality, we now give an overview of the tion of violation of the Bell inequality [1] has brought re- logical context (Fig. 1). For pedagogical purposes it is newed attention to the Einstein-Podolsky-Rosen (EPR) natural to present the analysis of the experimental re- family of experiments in which such violation is observed. sults in two stages, which we will call the \EPR analy- The violation of the Bell inequality is often described as sis", and the \Bell analysis" although historically they falsifying the combination of \locality" and \realism". were not presented in exactly this form [4, 5]; indeed, However, we will follow the approach of other authors both stages are combined in Bell's 1976 paper [2]. including Bell [2{4] who emphasize that the EPR results We will concentrate on Bohm's variant of EPR, the violate a single principle, strong locality. -
Theoretical Resolution of EPR Paradox
SSRG International Journal of Applied Physics ( SSRG – IJAP ) – Volume 4 Issue 3 Sep to Dec 2017 Theoretical Resolution of EPR Paradox Tapan Kumar Ghosh Assistant Research Officer (Hydraulics), River Research Institute, Irrigation and Waterways Department West Bengal, PIN 741 246 India Abstract: such a limit that a comprehensive conclusion can be Bell’s inequality together with widely used drawn over the matter of dispute. CHSH inequality on joint expectation of spin states However two simple hypotheses can theoretically between Alice and Bob ends are taken as a decisive settle the matter in line with the experimental theorem to challenge EPR Paradox. All experiments evidences against EPR paradox – on the polarisation states of entangled particles Hypotheses 1: ‘Properties’ do not exist prior to n i.e. violate Bell’s inequality as well as CHSH inequality ‘counterfactual definiteness’ is meaningless in and Einstein’s version of reality now is considered quantum world. wrong somehow. Bell’s argument clearly shows that Hypotheses 2:‘Conservation Laws’ operate only on quantum mechanics simultaneously can not justify measured values and therefore have no difficulties both ‘locality’ and ‘counterfactual definiteness’. being non-local. ‘Locality’ means that no causal connection can be With these two hypotheses one can easily made faster than light. ‘Counterfactual definiteness’, calculate the joint expectation for the outcome at Alice sometimes called ‘realism’ refers to the assumption on and Bob ends. However this article is intended to the existence of properties of objects prior to proceed without these hypotheses and the resulting measurement. This paper shows on the contrary that contradiction with the prediction of quantum Quantum Mechanics is neither. -
Physics of Information in Nonequilibrium Systems A
PHYSICS OF INFORMATION IN NONEQUILIBRIUM SYSTEMS A THESIS SUBMITTED TO THE GRADUATE DIVISION OF THE UNIVERSITY OF HAWAI`I AT MANOA¯ IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY IN PHYSICS MAY 2019 By Elan Stopnitzky Thesis Committee: Susanne Still, Chairperson Jason Kumar Yuriy Mileyko Xerxes Tata Jeffrey Yepez Copyright c 2019 by Elan Stopnitzky ii To my late grandmother, Rosa Stopnitzky iii ACKNOWLEDGMENTS I thank my wonderful family members Benny, Patrick, Shanee, Windy, and Yaniv for the limitless love and inspiration they have given to me over the years. I thank as well my advisor Susanna Still, who has always put great faith in me and encouraged me to pursue my own research ideas, and who has contributed to this work and influenced me greatly as a scientist; my friend and collaborator Lee Altenberg, whom I have learned countless things from and who contributed significantly to this thesis; and my collaborator Thomas E. Ouldridge, who also made important contributions. Finally, I would like to thank my partner Danelle Gallo, whose kindness and support have been invaluable to me throughout this process. iv ABSTRACT Recent advances in non-equilibrium thermodynamics have begun to reveal the funda- mental physical costs, benefits, and limits to the use of information. As the processing of information is a central feature of biology and human civilization, this opens the door to a physical understanding of a wide range of complex phenomena. I discuss two areas where connections between non-equilibrium physics and information theory lead to new results: inferring the distribution of biologically important molecules on the abiotic early Earth, and the conversion of correlated bits into work. -
Quantum Aspects of Life / Editors, Derek Abbott, Paul C.W
Quantum Aspectsof Life P581tp.indd 1 8/18/08 8:42:58 AM This page intentionally left blank foreword by SIR ROGER PENROSE editors Derek Abbott (University of Adelaide, Australia) Paul C. W. Davies (Arizona State University, USAU Arun K. Pati (Institute of Physics, Orissa, India) Imperial College Press ICP P581tp.indd 2 8/18/08 8:42:58 AM Published by Imperial College Press 57 Shelton Street Covent Garden London WC2H 9HE Distributed by World Scientific Publishing Co. Pte. Ltd. 5 Toh Tuck Link, Singapore 596224 USA office: 27 Warren Street, Suite 401-402, Hackensack, NJ 07601 UK office: 57 Shelton Street, Covent Garden, London WC2H 9HE Library of Congress Cataloging-in-Publication Data Quantum aspects of life / editors, Derek Abbott, Paul C.W. Davies, Arun K. Pati ; foreword by Sir Roger Penrose. p. ; cm. Includes bibliographical references and index. ISBN-13: 978-1-84816-253-2 (hardcover : alk. paper) ISBN-10: 1-84816-253-7 (hardcover : alk. paper) ISBN-13: 978-1-84816-267-9 (pbk. : alk. paper) ISBN-10: 1-84816-267-7 (pbk. : alk. paper) 1. Quantum biochemistry. I. Abbott, Derek, 1960– II. Davies, P. C. W. III. Pati, Arun K. [DNLM: 1. Biogenesis. 2. Quantum Theory. 3. Evolution, Molecular. QH 325 Q15 2008] QP517.Q34.Q36 2008 576.8'3--dc22 2008029345 British Library Cataloguing-in-Publication Data A catalogue record for this book is available from the British Library. Photo credit: Abigail P. Abbott for the photo on cover and title page. Copyright © 2008 by Imperial College Press All rights reserved. This book, or parts thereof, may not be reproduced in any form or by any means, electronic or mechanical, including photocopying, recording or any information storage and retrieval system now known or to be invented, without written permission from the Publisher. -
Simulation of the Bell Inequality Violation Based on Quantum Steering Concept Mohsen Ruzbehani
www.nature.com/scientificreports OPEN Simulation of the Bell inequality violation based on quantum steering concept Mohsen Ruzbehani Violation of Bell’s inequality in experiments shows that predictions of local realistic models disagree with those of quantum mechanics. However, despite the quantum mechanics formalism, there are debates on how does it happen in nature. In this paper by use of a model of polarizers that obeys the Malus’ law and quantum steering concept, i.e. superluminal infuence of the states of entangled pairs to each other, simulation of phenomena is presented. The given model, as it is intended to be, is extremely simple without using mathematical formalism of quantum mechanics. However, the result completely agrees with prediction of quantum mechanics. Although it may seem trivial, this model can be applied to simulate the behavior of other not easy to analytically evaluate efects, such as defciency of detectors and polarizers, diferent value of photons in each run and so on. For example, it is demonstrated, when detector efciency is 83% the S factor of CHSH inequality will be 2, which completely agrees with famous detector efciency limit calculated analytically. Also, it is shown in one-channel polarizers the polarization of absorbed photons, should change to the perpendicular of polarizer angle, at very end, to have perfect violation of the Bell inequality (2 √2 ) otherwise maximum violation will be limited to (1.5 √2). More than a half-century afer celebrated Bell inequality 1, nonlocality is almost totally accepted concept which has been proved by numerous experiments. Although there is no doubt about validity of the mathematical model proposed by Bell to examine the principle of the locality, it is comprehended that Bell’s inequality in its original form is not testable. -
Quantum Information Science and Quantum Metrology: Novel Systems and Applications
Quantum Information Science and Quantum Metrology: Novel Systems and Applications A dissertation presented by P´eterK´om´ar to The Department of Physics in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the subject of Physics Harvard University Cambridge, Massachusetts December 2015 c 2015 - P´eterK´om´ar All rights reserved. Thesis advisor Author Mikhail D. Lukin P´eterK´om´ar Quantum Information Science and Quantum Metrology: Novel Systems and Applications Abstract The current frontier of our understanding of the physical universe is dominated by quantum phenomena. Uncovering the prospects and limitations of acquiring and processing information using quantum effects is an outstanding challenge in physical science. This thesis presents an analysis of several new model systems and applications for quantum information processing and metrology. First, we analyze quantum optomechanical systems exhibiting quantum phenom- ena in both optical and mechanical degrees of freedom. We investigate the strength of non-classical correlations in a model system of two optical and one mechanical mode. We propose and analyze experimental protocols that exploit these correlations for quantum computation. We then turn our attention to atom-cavity systems involving strong coupling of atoms with optical photons, and investigate the possibility of using them to store information robustly and as relay nodes. We present a scheme for a robust two-qubit quantum gate with inherent error-detection capabilities. We consider several remote entanglement protocols employing this robust gate, and we use these systems to study the performance of the gate in practical applications. iii Abstract Finally, we present a new protocol for running multiple, remote atomic clocks in quantum unison. -
Violation of Bell Inequalities: Mapping the Conceptual Implications
International Journal of Quantum Foundations 7 (2021) 47-78 Original Paper Violation of Bell Inequalities: Mapping the Conceptual Implications Brian Drummond Edinburgh, Scotland. E-mail: [email protected] Received: 10 April 2021 / Accepted: 14 June 2021 / Published: 30 June 2021 Abstract: This short article concentrates on the conceptual aspects of the violation of Bell inequalities, and acts as a map to the 265 cited references. The article outlines (a) relevant characteristics of quantum mechanics, such as statistical balance and entanglement, (b) the thinking that led to the derivation of the original Bell inequality, and (c) the range of claimed implications, including realism, locality and others which attract less attention. The main conclusion is that violation of Bell inequalities appears to have some implications for the nature of physical reality, but that none of these are definite. The violations constrain possible prequantum (underlying) theories, but do not rule out the possibility that such theories might reconcile at least one understanding of locality and realism to quantum mechanical predictions. Violation might reflect, at least partly, failure to acknowledge the contextuality of quantum mechanics, or that data from different probability spaces have been inappropriately combined. Many claims that there are definite implications reflect one or more of (i) imprecise non-mathematical language, (ii) assumptions inappropriate in quantum mechanics, (iii) inadequate treatment of measurement statistics and (iv) underlying philosophical assumptions. Keywords: Bell inequalities; statistical balance; entanglement; realism; locality; prequantum theories; contextuality; probability space; conceptual; philosophical International Journal of Quantum Foundations 7 (2021) 48 1. Introduction and Overview (Area Mapped and Mapping Methods) Concepts are an important part of physics [1, § 2][2][3, § 1.2][4, § 1][5, p. -
Many-Body Entanglement in Classical & Quantum Simulators
Many-Body Entanglement in Classical & Quantum Simulators Johnnie Gray A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy of University College London. Department of Physics & Astronomy University College London January 15, 2019 2 3 I, Johnnie Gray, confirm that the work presented in this thesis is my own. Where information has been derived from other sources, I confirm that this has been indicated in the work. Abstract Entanglement is not only the key resource for many quantum technologies, but es- sential in understanding the structure of many-body quantum matter. At the interface of these two crucial areas are simulators, controlled systems capable of mimick- ing physical models that might escape analytical tractability. Traditionally, these simulations have been performed classically, where recent advancements such as tensor-networks have made explicit the limitation entanglement places on scalability. Increasingly however, analog quantum simulators are expected to yield deep insight into complex systems. This thesis advances the field in across various interconnected fronts. Firstly, we introduce schemes for verifying and distributing entanglement in a quantum dot simulator, tailored to specific experimental constraints. We then confirm that quantum dot simulators would be natural candidates for simulating many-body localization (MBL) - a recently emerged phenomenon that seems to evade traditional statistical mechanics. Following on from that, we investigate MBL from an entanglement perspective, shedding new light on the nature of the transi- tion to it from a ergodic regime. As part of that investigation we make use of the logarithmic negativity, an entanglement measure applicable to many-body mixed states. -
The Catalan Mathematical Society EMS June 2000 3 EDITORIAL
CONTENTS EDITORIAL TEAM EUROPEAN MATHEMATICAL SOCIETY EDITOR-IN-CHIEF ROBIN WILSON Department of Pure Mathematics The Open University Milton Keynes MK7 6AA, UK e-mail: [email protected] ASSOCIATE EDITORS STEEN MARKVORSEN Department of Mathematics Technical University of Denmark Building 303 NEWSLETTER No. 36 DK-2800 Kgs. Lyngby, Denmark e-mail: [email protected] KRZYSZTOF CIESIELSKI June 2000 Mathematics Institute Jagiellonian University Reymonta 4 30-059 Kraków, Poland EMS News : Agenda, Editorial, 3ecm, Bedlewo Meeting, Limes Project ........... 2 e-mail: [email protected] KATHLEEN QUINN Open University [address as above] Catalan Mathematical Society ........................................................................... 3 e-mail: [email protected] SPECIALIST EDITORS The Hilbert Problems ....................................................................................... 10 INTERVIEWS Steen Markvorsen [address as above] SOCIETIES Interview with Peter Deuflhard ....................................................................... 14 Krzysztof Ciesielski [address as above] EDUCATION Vinicio Villani Interview with Jaroslav Kurzweil ..................................................................... 16 Dipartimento di Matematica Via Bounarotti, 2 56127 Pisa, Italy A Major Challenge for Mathematicians ........................................................... 20 e-mail: [email protected] MATHEMATICAL PROBLEMS Paul Jainta EMS Position Paper: Towards a European Research Area ............................. 24 -
Quantum, Classical, and Total Amount of Correlations in a Quantum State
PHYSICAL REVIEW A 72, 032317 ͑2005͒ Quantum, classical, and total amount of correlations in a quantum state Berry Groisman,1,* Sandu Popescu,1,2,† and Andreas Winter3,‡ 1H. H. Wills Physics Laboratory, University of Bristol, Tyndall Avenue, Bristol BS8 1TL, United Kingdom 2Hewlett-Packard Laboratories, Stoke Gifford, Bristol BS12 6QZ, United Kingdom 3Department of Mathematics, University of Bristol, Bristol BS8 1TW, United Kingdom ͑Received 1 February 2005; published 13 September 2005͒ We give an operational definition of the quantum, classical, and total amounts of correlations in a bipartite quantum state. We argue that these quantities can be defined via the amount of work ͑noise͒ that is required to erase ͑destroy͒ the correlations: for the total correlation, we have to erase completely, for the quantum corre- lation we have to erase until a separable state is obtained, and the classical correlation is the maximal corre- lation left after erasing the quantum correlations. In particular, we show that the total amount of correlations is equal to the quantum mutual information, thus providing it with a direct operational interpretation. As a by-product, we obtain a direct, operational, and elementary proof of strong subadditivity of quantum entropy. DOI: 10.1103/PhysRevA.72.032317 PACS number͑s͒: 03.67.Mn, 03.65.Ud, 03.65.Yz I. INTRODUCTION 1 1 = ͉⌽+͗͘⌽+͉ + ͉⌽−͗͘⌽−͉, 2 2 Landauer ͓1͔, in analyzing the physical nature of ͑classi- cal͒ information, showed that the amount of information where stored, say, in a computer’s memory, is proportional to the 1 work required to erase the memory ͑reset to zero all the bits͒. -
Multiple-Time States and Multiple-Time Measurements in Quantum Mechanics Yakir Aharonov Chapman University, [email protected]
Chapman University Chapman University Digital Commons Mathematics, Physics, and Computer Science Science and Technology Faculty Articles and Faculty Articles and Research Research 2009 Multiple-Time States and Multiple-Time Measurements In Quantum Mechanics Yakir Aharonov Chapman University, [email protected] Sandu Popescu University of Bristol Jeff olT laksen Chapman University, [email protected] Lev Vaidman Tel Aviv University Follow this and additional works at: http://digitalcommons.chapman.edu/scs_articles Part of the Quantum Physics Commons Recommended Citation Aharonov, Yakir, Sandu Popescu, Jeff oT llaksen, and Lev Vaidman. "Multiple-time States and Multiple-time Measurements in Quantum Mechanics." Physical Review A 79.5 (2009). doi: 10.1103/PhysRevA.79.052110 This Article is brought to you for free and open access by the Science and Technology Faculty Articles and Research at Chapman University Digital Commons. It has been accepted for inclusion in Mathematics, Physics, and Computer Science Faculty Articles and Research by an authorized administrator of Chapman University Digital Commons. For more information, please contact [email protected]. Multiple-Time States and Multiple-Time Measurements In Quantum Mechanics Comments This article was originally published in Physical Review A, volume 79, issue 5, in 2009. DOI: 10.1103/ PhysRevA.79.052110 Copyright American Physical Society This article is available at Chapman University Digital Commons: http://digitalcommons.chapman.edu/scs_articles/281 PHYSICAL REVIEW A 79, 052110 ͑2009͒ Multiple-time states and multiple-time measurements in quantum mechanics Yakir Aharonov,1,2 Sandu Popescu,3,4 Jeff Tollaksen,2 and Lev Vaidman1 1Raymond and Beverly Sackler School of Physics and Astronomy, Tel Aviv University, 69978 Tel Aviv, Israel 2Department of Physics, Computational Science, and Engineering, Schmid College of Science, Chapman University, 1 University Drive, Orange, California 92866, USA 3H.H.