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Dear Fellow Quantum Mechanics;
Dear Fellow Quantum Mechanics Jeremy Bernstein Abstract: This is a letter of inquiry about the nature of quantum mechanics. I have been reflecting on the sociology of our little group and as is my wont here are a few notes. I see our community divided up into various subgroups. I will try to describe them beginning with a small group of elderly but distinguished physicist who either believe that there is no problem with the quantum theory and that the young are wasting their time or that there is a problem and that they have solved it. In the former category is Rudolf Peierls and in the latter Phil Anderson. I will begin with Peierls. In the January 1991 issue of Physics World Peierls published a paper entitled “In defence of ‘measurement’”. It was one of the last papers he wrote. It was in response to his former pupil John Bell’s essay “Against measurement” which he had published in the same journal in August of 1990. Bell, who had died before Peierls’ paper was published, had tried to explain some of the difficulties of quantum mechanics. Peierls would have none of it.” But I do not agree with John Bell,” he wrote,” that these problems are very difficult. I think it is easy to give an acceptable account…” In the rest of his short paper this is what he sets out to do. He begins, “In my view the most fundamental statement of quantum mechanics is that the wave function or more generally the density matrix represents our knowledge of the system we are trying to describe.” Of course the wave function collapses when this knowledge is altered. -
Multi-Dimensional Entanglement Transport Through Single-Mode Fibre
Multi-dimensional entanglement transport through single-mode fibre Jun Liu,1, ∗ Isaac Nape,2, ∗ Qianke Wang,1 Adam Vall´es,2 Jian Wang,1 and Andrew Forbes2 1Wuhan National Laboratory for Optoelectronics, School of Optical and Electronic Information, Huazhong University of Science and Technology, Wuhan 430074, Hubei, China. 2School of Physics, University of the Witwatersrand, Private Bag 3, Wits 2050, South Africa (Dated: April 8, 2019) The global quantum network requires the distribution of entangled states over long distances, with significant advances already demonstrated using entangled polarisation states, reaching approxi- mately 1200 km in free space and 100 km in optical fibre. Packing more information into each photon requires Hilbert spaces with higher dimensionality, for example, that of spatial modes of light. However spatial mode entanglement transport requires custom multimode fibre and is lim- ited by decoherence induced mode coupling. Here we transport multi-dimensional entangled states down conventional single-mode fibre (SMF). We achieve this by entangling the spin-orbit degrees of freedom of a bi-photon pair, passing the polarisation (spin) photon down the SMF while ac- cessing multi-dimensional orbital angular momentum (orbital) subspaces with the other. We show high fidelity hybrid entanglement preservation down 250 m of SMF across multiple 2 × 2 dimen- sions, demonstrating quantum key distribution protocols, quantum state tomographies and quantum erasers. This work offers an alternative approach to spatial mode entanglement transport that fa- cilitates deployment in legacy networks across conventional fibre. Entanglement is an intriguing aspect of quantum me- chanics with well-known quantum paradoxes such as those of Einstein-Podolsky-Rosen (EPR) [1], Hardy [2], and Leggett [3]. -
On Monte Carlo Time-Dependent Variational Principles
On Monte Carlo Time-Dependent Variational Principles Von der QUEST-Leibniz-Forschungsschule der Gottfried Wilhelm Leibniz Universit¨atHannover zur Erlangung des akademischen Grades Doktor der Naturwissenschaften { Doctor rerum naturalium { genehmigte Dissertation von FABIANWOLFGANGG UNTERTRANSCHEL¨ Geboren am 10.01.1987 in Gehrden 2016 0 Erstpr¨ufer : Prof. Dr. Reinhard F. Werner Zweitpr¨ufer : Prof. Dr. Klemens Hammerer Beratendes Mitglied des Pr¨ufungsausschusses : Prof. Dr. Tobias J. Osborne Vorsitzender des Pr¨ufungsausschusses : Prof. Dr. Rolf Haug Tag der Promotion: 17. Dezember 2015 On Monte Carlo Time-Dependent Variational Principles Fabian W. G. Transchel Abstract The present dissertation is concerned with the development and implementation of a novel scheme for quantitative, numeric approximation of the dynamics of quantum lattice systems based on the Time-Dependent Variational Principle together with Monte Carlo techniques in order to include dissipative interactions. The specific implementation is demonstrated on both common and not yet in-detail explored Heisenberg- and Fermi-Hubbard models in one and two dimensions. Additionally, the technical requirements regarding computational complexity and capacity are discussed, especially with regards toward parallelizable components of the imple- mentation. Concluding remarks include prospects with respect to application and extension of the presented methods. Keywords: Monte Carlo method, Dissipative Dynamics, Lindblad Equation iii Zusammenfassung Die vorliegende Dissertation befasst sich mit der Entwicklung und Umsetzung eines neuartigen Schemas zur quantitativen numerischen N¨aherung der Dynamik von Quantengittersystemen auf Grundlage des zeitabh¨angigenVariationsprinzips unter Zuhilfenahme von Monte-Carlo-Techniken zur Einbeziehung von dissipativen Wech- selwirkungen. Die Implementierung wird anhand von Beispielen f¨urHeisenberg- und Fermi-Hubbard-Modellen in einer und zwei Dimensionen gezeigt und erl¨autert. -
Scientific Report for the Year 2000
The Erwin Schr¨odinger International Boltzmanngasse 9 ESI Institute for Mathematical Physics A-1090 Wien, Austria Scientific Report for the Year 2000 Vienna, ESI-Report 2000 March 1, 2001 Supported by Federal Ministry of Education, Science, and Culture, Austria ESI–Report 2000 ERWIN SCHRODINGER¨ INTERNATIONAL INSTITUTE OF MATHEMATICAL PHYSICS, SCIENTIFIC REPORT FOR THE YEAR 2000 ESI, Boltzmanngasse 9, A-1090 Wien, Austria March 1, 2001 Honorary President: Walter Thirring, Tel. +43-1-4277-51516. President: Jakob Yngvason: +43-1-4277-51506. [email protected] Director: Peter W. Michor: +43-1-3172047-16. [email protected] Director: Klaus Schmidt: +43-1-3172047-14. [email protected] Administration: Ulrike Fischer, Eva Kissler, Ursula Sagmeister: +43-1-3172047-12, [email protected] Computer group: Andreas Cap, Gerald Teschl, Hermann Schichl. International Scientific Advisory board: Jean-Pierre Bourguignon (IHES), Giovanni Gallavotti (Roma), Krzysztof Gawedzki (IHES), Vaughan F.R. Jones (Berkeley), Viktor Kac (MIT), Elliott Lieb (Princeton), Harald Grosse (Vienna), Harald Niederreiter (Vienna), ESI preprints are available via ‘anonymous ftp’ or ‘gopher’: FTP.ESI.AC.AT and via the URL: http://www.esi.ac.at. Table of contents General remarks . 2 Winter School in Geometry and Physics . 2 Wolfgang Pauli und die Physik des 20. Jahrhunderts . 3 Summer Session Seminar Sophus Lie . 3 PROGRAMS IN 2000 . 4 Duality, String Theory, and M-theory . 4 Confinement . 5 Representation theory . 7 Algebraic Groups, Invariant Theory, and Applications . 7 Quantum Measurement and Information . 9 CONTINUATION OF PROGRAMS FROM 1999 and earlier . 10 List of Preprints in 2000 . 13 List of seminars and colloquia outside of conferences . -
Quantum Theory Needs No 'Interpretation'
Quantum Theory Needs No ‘Interpretation’ But ‘Theoretical Formal-Conceptual Unity’ (Or: Escaping Adán Cabello’s “Map of Madness” With the Help of David Deutsch’s Explanations) Christian de Ronde∗ Philosophy Institute Dr. A. Korn, Buenos Aires University - CONICET Engineering Institute - National University Arturo Jauretche, Argentina Federal University of Santa Catarina, Brazil. Center Leo Apostel fot Interdisciplinary Studies, Brussels Free University, Belgium Abstract In the year 2000, in a paper titled Quantum Theory Needs No ‘Interpretation’, Chris Fuchs and Asher Peres presented a series of instrumentalist arguments against the role played by ‘interpretations’ in QM. Since then —quite regardless of the publication of this paper— the number of interpretations has experienced a continuous growth constituting what Adán Cabello has characterized as a “map of madness”. In this work, we discuss the reasons behind this dangerous fragmentation in understanding and provide new arguments against the need of interpretations in QM which —opposite to those of Fuchs and Peres— are derived from a representational realist understanding of theories —grounded in the writings of Einstein, Heisenberg and Pauli. Furthermore, we will argue that there are reasons to believe that the creation of ‘interpretations’ for the theory of quanta has functioned as a trap designed by anti-realists in order to imprison realists in a labyrinth with no exit. Taking as a standpoint the critical analysis by David Deutsch to the anti-realist understanding of physics, we attempt to address the references and roles played by ‘theory’ and ‘observation’. In this respect, we will argue that the key to escape the anti-realist trap of interpretation is to recognize that —as Einstein told Heisenberg almost one century ago— it is only the theory which can tell you what can be observed. -
Black Holes and Qubits
Subnuclear Physics: Past, Present and Future Pontifical Academy of Sciences, Scripta Varia 119, Vatican City 2014 www.pas.va/content/dam/accademia/pdf/sv119/sv119-duff.pdf Black Holes and Qubits MICHAEL J. D UFF Blackett Labo ratory, Imperial C ollege London Abstract Quantum entanglement lies at the heart of quantum information theory, with applications to quantum computing, teleportation, cryptography and communication. In the apparently separate world of quantum gravity, the Hawking effect of radiating black holes has also occupied centre stage. Despite their apparent differences, it turns out that there is a correspondence between the two. Introduction Whenever two very different areas of theoretical physics are found to share the same mathematics, it frequently leads to new insights on both sides. Here we describe how knowledge of string theory and M-theory leads to new discoveries about Quantum Information Theory (QIT) and vice-versa (Duff 2007; Kallosh and Linde 2006; Levay 2006). Bekenstein-Hawking entropy Every object, such as a star, has a critical size determined by its mass, which is called the Schwarzschild radius. A black hole is any object smaller than this. Once something falls inside the Schwarzschild radius, it can never escape. This boundary in spacetime is called the event horizon. So the classical picture of a black hole is that of a compact object whose gravitational field is so strong that nothing, not even light, can escape. Yet in 1974 Stephen Hawking showed that quantum black holes are not entirely black but may radiate energy, due to quantum mechanical effects in curved spacetime. In that case, they must possess the thermodynamic quantity called entropy. -
Is There Ontology After Bell's Theorem?
IS THERE ONTOLOGY AFTER BELL'S THEOREM? A Speech given to the Philosophical Club of Cleveland February 14, 1984 By John Heighway 1 IS THERE ONTOLOGY AFTER BELL'S THEOREM? I feel that it’s unfair to use a title containing a generally unfamiliar term, in this case "Bell's Theorem," without promptly giving some explanation. It happens that logic demands a rather lengthy lead-in, so let me quote here, as a sort of "jacket blurb" introduction, the abstract of the excellent review article on Bell's Theorem, by John Clauser and Abner Shimony. Bell's Theorem represents a significant advance in understanding the conceptual foundations of quantum mechanics. The theorem shows that essentially all local theories of natural phenomena that are formulated within the framework of realism may be tested using a single experimental arrangement. Moreover, the predictions by these theories must significantly differ from those by quantum mechanics. Experimental results evidently refute the theorem's predictions for these theories and favour those of quantum mechanics. The conclusions are philosophically startling: either one must totally abandon the realistic philosophy of most working scientists, or dramatically revise our concept of space-time. If I were permitted to edit this statement, I would just add the words "or both" to the final sentence. Ontology is a branch of metaphysics dealing with theories of reality or being. Almost all scientists, past and present, have embraced without reservation the theory called realism, which holds that external reality exists and possesses definite properties, altogether independently of whether or not those properties are observed by someone. -
Brief Newsletter from World Scientific February 2017
Brief Newsletter from World Scientific February 2017 Exclusive Interview with 2003 Nobel Laureate One of the Top Condensed Matter Theorists and World Scientific Author Anthony Leggett Sir Professor Anthony James Leggett is a distinguished physicist who was awarded the Nobel Prize in Physics in 2003 for his pioneering contributions to the theory of superconductors and superfluids. He is currently a professor at the University of Illinois at Urbana-Champaign. Prof Leggett gave a presentation at the 2016 APS March Meeting in Baltimore, USA on “Reflections on the past, present and future of condensed matter physics”. In a phone interview, he shared with us some of his thoughts and further musings on the future of condensed matter physics. Paradigm Shift and Our Quest for the Unknown Chad Hollingsworth Your talk at the APS March Meeting 2016 mentioned developments That probably depends on your current tenure status! Certainly, if that you classified as “paradigm shifts”. Are there any recent you have a secure, tenured job (as I have been fortunate enough to discoveries that you would classify as paradigm shifts? have for the last few decades), then I think most certainly it’s better Well, if we go slightly outside the area of condensed matter physics to explore the unknown. But, of course, I appreciate that in the current as it has been conventionally defined, then, undoubtedly, any employment situation, people who have not got a tenured job need revolution which overthrew the view of quantum mechanics as a to think about their future. This may well be a rather strong pressure complete account of the world would, I think, certainly qualify as a to basically explore the known further. -
Arxiv:Quant-Ph/0101077 V1 17 Jan 2001 His Get When Rect W Y B Mals.” Cup of Ab of Miliar
100 Years of the Quantum Max Tegmark Dept. of Physics, Univ. of Pennsylvania, Philadelphia, PA 19104; [email protected] John Archibald Wheeler Princeton University, Department of Physics, Princeton, NJ 08544; [email protected] (An abbreviated version of this article, with much better graphics, was published in the Feb. 2001 issue of Scientific American, p.68-75.) Abstract: As quantum theory celebrates its 100th birthday, spectacular successes are mixed with outstanding puzzles and promises of new technologies. This article reviews both the successes of quantum theory and the ongoing debate about its consequences for issues ranging from quantum computation to consciousness, parallel universes and the nature of physical reality. We argue that modern experiments and the discovery of decoherence have have shifted prevailing quantum inter- pretations away from wave function collapse towards unitary physics, and discuss quantum processes in the framework of a tripartite subject-object-environment decomposition. We conclude with some speculations on the bigger picture and the search for a unified theory of quantum gravity. \...in a few years, all the great physical constants will ever, this involved an assumption so bizarre that even have been approximately estimated, and [...] the only oc- he distanced himself from it for many years afterwards: cupation which will then be left to the men of science will that energy was only emitted in certain finite chunks, or be to carry these measurement to another place of deci- \quanta". Yet this strange assumption proved extremely mals." As we enter the 21st century amid much brouhaha successful. Inspired by Planck's quantum hypothesis, Pe- about past achievements, this sentiment may sound fa- ter Debye showed that the strange thermal behavior of miliar. -
Ccjun12-Cover Vb.Indd
CERN Courier June 2012 Faces & Places I NDUSTRY CERN supports new centre for business incubation in the UK To bridge the gap between basic science and industry, CERN and the Science and Technology Facilities Council (STFC) have launched a new business-incubation centre in the UK. The centre will support businesses and entrepreneurs to take innovative technologies related to high-energy physics from technical concept to market reality. The centre, at STFC’s Daresbury Science and Innovation Campus, follows the success of a business-incubation centre at the STFC’s Harwell campus, which has run for 10 years with the support of the European Space Agency (ESA). The ESA Business Incubation Centre (ESA BIC) supports entrepreneurs and hi-tech start-up companies to translate space technologies, applications and services into viable nonspace-related business ideas. The CERN-STFC BIC will nurture innovative ideas based on technologies developed at CERN, with a direct contribution from CERN in terms of expertise. The centre is managed by STFC Innovations Limited, the technology-transfer office of STFC, which will provide John Womersley, CEO of STFC, left, and Steve Myers, CERN’s director of accelerators and successful applicants with entrepreneurial technology, at the launch of the CERN-STFC Business Incubation Centre on the Daresbury support, including a dedicated business Science and Innovation Campus. (Image credit: STFC.) champion to help with business planning, accompanied technical visits to CERN as business expertise from STFC and CERN. total funding of up to £40,000 per company, well as access to scientific, technical and The selected projects will also receive a provided by STFC. -
Guide to Wolfgang Kurt Hermann Panofsky Papers, 1932-2008 Collection SLAC003 SLAC National Accelerator Laboratory, Stanford University
Guide to Wolfgang Kurt Hermann Panofsky Papers, 1932-2008 Collection SLAC003 SLAC National Accelerator Laboratory, Stanford University Contact Information: Archives, History & Records Office SLAC National Accelerator Laboratory 2575 Sand Hill Road MS97 Menlo Park, CA 94025 Phone: (650) 926-5376 Email: [email protected] URL: http://www.slac.stanford.edu/history/ ©2018 SLAC National Accelerator Laboratory. All rights reserved. Panofsky Papers Guide Contents Descriptive Summary...................................................................................................................... 2 Administrative Information ............................................................................................................ 2 Biographical Note ....................................................................................................................... 3 Scope and Content .................................................................................................................... 12 Arrangement ............................................................................................................................. 12 Related Material ........................................................................................................................ 21 1 Panofsky Papers Guide Descriptive Summary Title: Wolfgang Kurt Hermann Panofsky Papers, 1932-2008 Collection Number: SLAC003 Creator: Panofsky, Wolfgang Kurt Hermann Extent: 220 cubic feet Repository: Stanford University. SLAC National Accelerator Laboratory. -
A Contribuição De Chien Shiung Wu Para a Teoria Quântica
UNIVERSIDADE FEDERAL DA BAHIA UNIVERSIDADE ESTADUAL DE FEIRA DE SANTANA PROGRAMA DE PÓS-GRADUAÇÃO EM ENSINO, FILOSOFIA E HISTÓRIA DAS CIÊNCIAS ANGEVALDO MENEZES MAIA FILHO PARA UMA HISTÓRIA DAS MULHERES NA CIÊNCIA: A CONTRIBUIÇÃO DE CHIEN SHIUNG WU PARA A TEORIA QUÂNTICA Salvador 2018 ANGEVALDO MENEZES MAIA FILHO PARA UMA HISTÓRIA DAS MULHERES NA CIÊNCIA: A CONTRIBUIÇÃO DE CHIEN SHIUNG WU PARA A TEORIA QUÂNTICA Dissertação apresentada ao Programa de Pós- Graduação em Ensino, Filosofia e História das Ciências, da Universidade Federal da Bahia e da Universidade Estadual de Feira de Santana como requisito parcial para a obtenção do título de Mestre em Ensino, Filosofia e História das Ciências. Orientadora: Profa. Dra. Indianara Lima Silva Salvador 2018 ANGEVALDO MENEZES MAIA FILHO PARA UMA HISTÓRIA DAS MULHERES NA CIÊNCIA: A CONTRIBUIÇÃO DE CHIEN SHIUNG WU PARA A TEORIA QUÂNTICA Dissertação apresentada como requisito parcial para obtenção do grau de mestre em 19 de abril de 2018, Programa de Pós-Graduação em Ensino, Filosofia e História das Ciências, da Universidade Federal da Bahia e da Universidade Estadual de Feira de Santana. 19 de abril de 2018 Banca Examinadora _______________________________________________ Professora Doutora Indianara Lima Silva _______________________________________________ Professora Doutora Maria Margaret Lopes _______________________________________________ Professor Doutor Olival Freire Júnior AGRADECIMENTOS Como não poderia deixar de ser, os agradecimentos revelam o quão importante são as pessoas que nos cercam e o quanto pode ser difícil, no meu caso, absolutamente impossível, realizar um trabalho individualmente. Agradeço a Josenice Assunção Maia e Angevaldo Maia, pessoas que tive a sorte de ter enquanto genitores me apoiando incondicionalmente desde sempre, confiando e acreditando nas minhas escolhas, a maior e inesgotável fonte de amor que pude encontrar na vida.