Strong Loophole-Free Test of Local Realism*
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Airborne Demonstration of a Quantum Key Distribution Receiver Payload
Airborne demonstration of a quantum key distribution receiver payload Christopher J. Pugh1;2, Sarah Kaiser1;2z, Jean-Philippe Bourgoin1;2, Jeongwan Jin1;2, Nigar Sultana1;3, Sascha Agne1;2, Elena Anisimova1;2, Vadim Makarov2;1;3, Eric Choi1x, Brendon L. Higgins1;2 and Thomas Jennewein1;2 1 Institute for Quantum Computing, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada 2 Department of Physics and Astronomy, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada 3 Department of Electrical and Computer Engineering, University of Waterloo, 200 University Avenue West, Waterloo, Ontario N2L 3G1, Canada E-mail: [email protected] Abstract. Satellite-based quantum terminals are a feasible way to extend the reach of quantum communication protocols such as quantum key distribution (QKD) to the global scale. To that end, prior demonstrations have shown QKD transmissions from airborne platforms to receivers on ground, but none have shown QKD transmissions from ground to a moving aircraft, the latter scenario having simplicity and flexibility advantages for a hypothetical satellite. Here we demonstrate QKD from a ground transmitter to a receiver prototype mounted on an airplane in flight. We have specifically designed our receiver prototype to consist of many components that are compatible with the environment and resource constraints of a satellite. Coupled with our relocatable ground station system, optical links with distances of 3{10 km were maintained and quantum signals transmitted while traversing angular rates similar to those observed of low-Earth-orbit satellites. For some passes of the aircraft over the ground station, links were established within 10 s of position data transmission, and with link times of a few minutes and received quantum bit error rates typically ≈3{5 %, arXiv:1612.06396v2 [quant-ph] 9 Jun 2017 we generated secure keys up to 868 kb in length. -
A Question of Quantum Reality 24 September 2020
A question of quantum reality 24 September 2020 virtuality. Bell spent most of his working life at CERN in Geneva, Switzerland, and Bertlmann first met him when he took up a short-term fellowship there in 1978. Bell had first presented his theorem in a seminal paper published in 1964, but this was largely neglected until the 1980s and the introduction of quantum information. Bertlmann discusses the concept of Bell inequalities, which arise through thought experiments in which a pair of spin-½ particles propagate in opposite directions and are measured Credit: Pixabay/CC0 Public Domain by independent observers, Alice and Bob. The Bell inequality distinguishes between local realism—the 'common sense' view in which Alice's observations do not depend on Bob's, and vice versa—and Physicist Reinhold Bertlmann of the University of quantum mechanics, or, specifically, quantum Vienna, Austria has published a review of the work entanglement. Two quantum particles, such as of his late long-term collaborator John Stewart Bell those in the Alice-Bob situation, are entangled of CERN, Geneva in EPJ H. This review, "Real or when the state measured by one observer Not Real: that is the question," explores Bell's instantaneously influences that of the other. This inequalities and his concepts of reality and theory is the basis of quantum information. explains their relevance to quantum information and its applications. And quantum information is no longer just an abstruse theory. It is finding applications in fields as John Stewart Bell's eponymous theorem and diverse as security protocols, cryptography and inequalities set out, mathematically, the contrast quantum computing. -
Final Copy 2020 11 26 Stylia
This electronic thesis or dissertation has been downloaded from Explore Bristol Research, http://research-information.bristol.ac.uk Author: Stylianou, Nicos Title: On 'Probability' A Case of Down to Earth Humean Propensities General rights Access to the thesis is subject to the Creative Commons Attribution - NonCommercial-No Derivatives 4.0 International Public License. A copy of this may be found at https://creativecommons.org/licenses/by-nc-nd/4.0/legalcode This license sets out your rights and the restrictions that apply to your access to the thesis so it is important you read this before proceeding. Take down policy Some pages of this thesis may have been removed for copyright restrictions prior to having it been deposited in Explore Bristol Research. However, if you have discovered material within the thesis that you consider to be unlawful e.g. breaches of copyright (either yours or that of a third party) or any other law, including but not limited to those relating to patent, trademark, confidentiality, data protection, obscenity, defamation, libel, then please contact [email protected] and include the following information in your message: •Your contact details •Bibliographic details for the item, including a URL •An outline nature of the complaint Your claim will be investigated and, where appropriate, the item in question will be removed from public view as soon as possible. On ‘Probability’ A Case of Down to Earth Humean Propensities By NICOS STYLIANOU Department of Philosophy UNIVERSITY OF BRISTOL A dissertation submitted to the University of Bristol in ac- cordance with the requirements of the degree of DOCTOR OF PHILOSOPHY in the Faculty of Arts. -
Disproof of John Stewart Bell
Disproof of John Stewart Bell T. Liffert 4th October 2020 Abstract The proof of John Stewart Bell [1] [2] is based on wrong premises. A deterministic model for a hidden mechanism with an parameter λ is therefor possible. This model is possible by an integration of the experimental context into the wave function 1 The basic experiment The following considerations are based on an experiment with a pair of en- tangled photons, each of them meets a polarisation filter. The crucial phe- nomenon consists of the fact, that, if the polarisation filters are adjusted identically, the photons react always identically: Either both will be ab- sorbed or both will be transmitted. For the angular difference Φ between the polarisation filter adjustments the probability, that both photons give identi- cal measurement results, is the square of the cosine of that angular difference (law of Malus)[3]. The set of the possible measurement results is a binary one, it can be referred to by expressions like f0; 1g or f+1; −1g. For later considerations of serie experiments and related expected values I use the set f+1; −1g, for the treatment of the proof variant according to Wigner-Bell I choose the set f0; 1g. I use the following assignments for measurement results and eigenstates • 0 j0i ! 1 • 1 j1i ! −1 May α denote the measurement result of the left photon and β the one of the right photon. The upper proposition for the conditional probability P of identical measurement results given the angular difference Φ one would write like this: P (α = βjΦ) = cos2 Φ (1) 1 1.1 The quantum mechanical doctrine In the literature that I know there is a strict separation between the quantum state jΨi of the pair of photons on the one hand and the experimental context, consisting of nothing more than the angular difference of the polarisation filters or the polarizers, on the other hand. -
2020.07.31 Jennewein Satellites
7/31/20 Novel techniques for ground to space quantumRESEARCH channels ◥ transmitting qubits over long distances a truly REVIEW formidable endeavor. Because qubits cannot be copied or amplified, repetition or signalIQC am- @ 2019: plification are ruled out as a means to overcome31 faculty QUANTUM INFORMATION imperfections, and a radically new technological development—such as quantum repeaters157— isGrad students needed in order to build a quantum internet57 Postdoc Quantum internet: A vision (Figs. 2 and 3) (5). We are now at an exciting moment in1800+ time, publications akin to the eve of the classical internet. In late for the road ahead 1969, the first message was sent over the$600M+ nas- funding cent four-node network that was then13 still spin re- -offs 1* 1 1,2 Thomas Jennewein Stephanie Wehner , David Elkouss , Ronald Hanson ferred to as the Advanced Research Projects Institute for Quantum Computing & Department of PhysicsAgency Network (ARPANET). Recent technolog- The internet a vast network that enables simultaneous long-range classical — and Astronomy,ical progress (6–9)nowsuggeststhatwemaysee communication has had a revolutionary impact on our world. The vision of a quantum — the first small-scale implementations of quan- internet is to fundamentally enhance internet technology by enabling quantumUniversity of Waterloo tum networks within the next 5 years. communication between any two points on Earth. Such a quantum internet may operate in [email protected] first glance, realizing a quantum internet parallel to the internet that we have today and connect quantum processors in order to 2020.07(Fig. 3) may seem even more difficult than build- achieve capabilities that are provably impossible by using only classical means. -
John S. Bell's Concept of Local Causality
John S. Bell’s concept of local causality Travis Norsena) Department of Physics, Smith College, McConnell Hall, Northampton, Massachusetts 01063 (Received 15 August 2008; accepted 6 August 2011) John Stewart Bell’s famous theorem is widely regarded as one of the most important developments in the foundations of physics. Yet even as we approach the 50th anniversary of Bell’s discovery, its meaning and implications remain controversial. Many workers assert that Bell’s theorem refutes the possibility suggested by Einstein, Podolsky, and Rosen (EPR) of supplementing ordinary quantum theory with “hidden” variables that might restore determinism and/or some notion of an observer- independent reality. But Bell himself interpreted the theorem very differently—as establishing an “essential conflict” between the well-tested empirical predictions of quantum theory and relativistic local causality. Our goal is to make Bell’s own views more widely known and to explain Bell’s little- known formulation of the concept of relativistic local causality on which his theorem rests. We also show precisely how Bell’s formulation of local causality can be used to derive an empirically testable Bell-type inequality and to recapitulate the EPR argument. VC 2011 American Association of Physics Teachers. [DOI: 10.1119/1.3630940] I. INTRODUCTION theory could be rendered compatible with local causality by following Newton and by denying that the theory in question In its most general sense, “local causality” is the idea that provided a complete description of the relevant phenomena. physical influences propagate continuously through space— This changed in 1905 with Einstein’s discovery of special that what Einstein famously called “spooky actions at a dis- relativity, which for the first time identified a class of causal 1 tance” are impossible. -
In the Dirac Tradition
In the Dirac tradition The late Richard Feynman - 'a way of looking at things so they appear not so mysterious'. It was Paul Dirac who cast quantum mechanics into the form we now use, and many generations of theo reticians openly acknowledge his in fluence on their thinking. When Dirac died in 1984, St. John's College, Cambridge, his base for most of his lifetime, institu ted an annual lecture in his memory at Cambridge. The first lecture, in 1986, attracted two heavyweights - Richard Feynman (see page 1) and Steven Weinberg. Far from using the lectures as a platform for their own work, in the Dirac tradition they pre sented stimulating material on deep underlying questions. (The lectures - 'Elementary Parti cles and the Laws of Physics' by Richard P. Feynman and Steven Weinberg - are published by Cam bridge University Press.) Richard Feynman When I was a young man, Dirac was my hero. He made a break through, a new method of doing tic quantum mechanics. However, cles, then to get the new wave- physics. He had the courage to the puzzle of negative energies that function from the old you must put simply guess at the form of an the equation presented, when it in a minus sign. It is easy to de equation, the equation we now call was solved, eventually showed monstrate that if Nature was non- the Dirac equation, and to try to in that the crucial idea necessary to relativistic, if things started out that terpret it afterwards. Maxwell in his wed quantum mechanics and relati way then it would be that way for day got his equations, but only in vity together was the existence of all time, and so the problem would an enormous mass of 'gear antiparticles. -
Is the Quantum State Real in the Hilbert Space Formulation?
Is the Quantum State Real in the Hilbert Space Formulation? Mani L. Bhaumik Department of Physics and Astronomy, University of California, Los Angeles, USA. E-mail: [email protected] Editors: Zvi Bern & Danko Georgiev Article history: Submitted on November 5, 2020; Accepted on December 18, 2020; Published on December 19, 2020. he persistent debate about the reality of a quan- 1 Introduction tum state has recently come under limelight be- Tcause of its importance to quantum informa- The debate about the reality of quantum states is as old tion and the quantum computing community. Almost as quantum physics itself. The objective reality underly- all of the deliberations are taking place using the ele- ing the manifestly bizarre behavior of quantum objects gant and powerful but abstract Hilbert space formal- is conspicuously at odds with our daily classical phys- ism of quantum mechanics developed with seminal ical reality. The scientific outlook of objective reality contributions from John von Neumann. Since it is commenced with the precepts of classical physics that rather difficult to get a direct perception of the events cemented our notion of reality for centuries. Discover- in an abstract vector space, it is hard to trace the ies starting in the last decade of the nineteenth century progress of a phenomenon. Among the multitude of revealing the uncanny quantum world in the microscopic recent attempts to show the reality of the quantum domain shook that perception. state in Hilbert space, the Pusey–Barrett–Rudolph With the particular exception of Einstein, who was the theory gets most recognition for their proof. -
The Quantum World the Disturbing Theory at the Heart of Reality
The Quantum World The disturbing theory at the heart of reality NEW SCIENTIST 629462_The_Quant_World_Book.indb 3 3/11/17 12:37 PM First published in Great Britain in 2017 by John Murray Learning. An Hachette UK company. Copyright © New Scientist 2017 The right of New Scientist to be identified as the Author of the Work has been asserted by it in accordance with the Copyright, Designs and Patents Act 1988. Database right Hodder & Stoughton (makers) All rights reserved. No part of this publication may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior written permission of the publisher, or as expressly permitted by law, or under terms agreed with the appropriate reprographic rights organization. Enquiries concerning reproduction outside the scope of the above should be sent to the Rights Department, John Murray Learning, at the address below. You must not circulate this book in any other binding or cover and you must impose this same condition on any acquirer. British Library Cataloguing in Publication Data: a catalogue record for this title is available from the British Library. Library of Congress Catalog Card Number: on file. ISBN: 978 1 47362 946 2 eISBN: 978 1 47362 947 9 1 The publisher has used its best endeavours to ensure that any website addresses referred to in this book are correct and active at the time of going to press. However, the publisher and the author have no responsibility for the websites and can make no guarantee that a site will remain live or that the content will remain relevant, decent or appropriate. -
IQC Newbit, Issue 31, Winter 2017
INSTITUTE FOR QUANT UM COMPUTING, UNIVERSITY OF WATERLOO, ONTARIO, CANADA | NEWBIT | ISSUE 30 | WINTER 2 | NEWBIT ISSUE CANADA ONTARIO, UNIVERSITY OF WATERLOO, UM COMPUTING, QUANT FOR INSTITUTE 30 | NEWBIT ISSUE CANADA ONTARIO, UNIVERSITY OF WATERLOO, QANTUM COMPUTING, FOR | INSTITUTE WINTER 2017 ONTAR UNIVERSITY OF WATERLOO, COMPUTING, QUANTUM FOR | INSTITUTE 30 | WINTER 2017 | NEWBIT ISSUE CANADA NEWBIT | ISSUE 31 ISSUE | IN WINTER 2017 this issue FROM THE EDITOR BUILDING A Much of the content in this issue focuses on taking the QUANTUM PLATFORM science out of our labs and offices. At IQC, we’ve been pg 04 doing this for some time through outreach initiatives and Researchers at IQC’s Laboratory for conferences, but it’s especially true this year with the first Ultracold Quantum Matter and Light keep travelling exhibition that made its debut at THEMUSEUM their cool as they develop platforms for in Kitchener in October. It will continue its path across quantum applications. Canada throughout 2017. Some of our researchers and staff will travel to the TAKING QUANTUM cities where QUANTUM: The Exhibition will land. This INTO SPACE is in addition to the talks they give at conferences and pg 08 courses at other institutions. In the fall, we had researchers IQC researchers first to demonstrate present at the ETSI/IQC Workshop on Quantum-Safe an uplink to an airborne quantum Cryptography in Toronto and at the London Mathematical satellite receiver prototype. Society Research School at Queen’s University Belfast. QUANTUM: THE An experiment by one of our research groups also went EXHIBITION outside the lab during the fall term – and I mean literally pg 12 outside. -
Physics in the Second Half of the Twentieth Century JOSÉ MANUEL SÁNCHEZ RON
the world after the revolution: physics in the second half of the twentieth century JOSÉ MANUEL SÁNCHEZ RON The great revolutions of the twentieth the state of movement of the observer, and mass, m, century is equivalent to energy, E (the famous expression E= m·c2, where c represents the speed of light), opened During the fi rst half of the twentieth century—actually, new doors for understanding the physical world. For the fi rst quarter—there were two major scientifi c example, this theory helped explain how it was possible revolutions. Those cognitive cataclysms took place in that radioactive elements (uranium, polonium, radium, physics, and are known as the relativist and quantum thorium) that had been studied for the fi rst time by revolutions. They are respectively related to the special Henri Becquerel (1852-1908) and Marie (1867-1934) and general theories of relativity (Einstein 1905a, and Pierre Curie (1859-1906), emit radiation in a 1915), and quantum mechanics (Heisenberg 1925, continuous manner with no apparent loss of mass. Schrödinger 1926). And then there was the general theory of relativity, which explained gravity by converting space—actually, Relativity four-dimensional space-time—into something curved, Much has been written, and will be written in the and with variable geometry! It was immediately future, about the importance of those theories apparent that, compared to Newton’s universal and their effect on physics as a whole, even before gravitation, Einstein’s new theory made it much easier to the middle of the century. Created to resolve the understand perceptible phenomena in the solar system increasingly evident “lack of understanding” between (it solved, for example, a century-old anomaly in the Newtonian mechanics and the electrodynamics of movement of Mercury’s perihelion). -
User:Guy Vandegrift/Timeline of Quantum Mechanics (Abridged)
User:Guy vandegrift/Timeline of quantum mechanics (abridged) • 1895 – Wilhelm Conrad Röntgen discovers X-rays in experiments with electron beams in plasma.[1] • 1896 – Antoine Henri Becquerel accidentally dis- covers radioactivity while investigating the work of Wilhelm Conrad Röntgen; he finds that uranium salts emit radiation that resembled Röntgen’s X- rays in their penetrating power, and accidentally dis- covers that the phosphorescent substance potassium uranyl sulfate exposes photographic plates.[1][3] • 1896 – Pieter Zeeman observes the Zeeman split- ting effect by passing the light emitted by hydrogen through a magnetic field. Wikiversity: • 1896–1897 Marie Curie investigates uranium salt First Journal of Science samples using a very sensitive electrometer device that was invented 15 years before by her husband and his brother Jacques Curie to measure electrical Under review. Condensed from Wikipedia’s Timeline of charge. She discovers that the emitted rays make the quantum mechanics at 13:07, 2 September 2015 (oldid surrounding air electrically conductive. [4] 679101670) • 1897 – Ivan Borgman demonstrates that X-rays and This abridged “timeline of quantum mechancis” shows radioactive materials induce thermoluminescence. some of the key steps in the development of quantum me- chanics, quantum field theories and quantum chemistry • 1899 to 1903 – Ernest Rutherford, who later became that occurred before the end of World War II [1][2] known as the “father of nuclear physics",[5] inves- tigates radioactivity and coins the terms alpha and beta rays in 1899 to describe the two distinct types 1 19th century of radiation emitted by thorium and uranium salts. [6] • 1859 – Kirchhoff introduces the concept of a blackbody and proves that its emission spectrum de- pends only on its temperature.[1] 2 20th century • 1860–1900 – Ludwig Eduard Boltzmann produces a 2.1 1900–1909 primitive diagram of a model of an iodine molecule that resembles the orbital diagram.