DOCSLIB.ORG

Trends in Quantum Optics∗ a Personal Perspective

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Trends in Quantum Optics∗ a Personal Perspective GENERAL ARTICLE Trends in Quantum Optics∗ A Personal Perspective Subhashish Banerjee and Arun M Jayannavar Here, we review some of the recent developments in quantum optics. After a brief introduction to the historical develop- ment of the subject, we discuss some of the modern aspects of quantum optics including atom field interactions, quantum state engineering, metamaterials and plasmonics, optomechan- ical systems, PT (parity-time) symmetry in quantum optics, as well as, quasi-probability distributions and quantum state tomography. Further, the recent developments in topological Subhashish Banerjee is a photonics is briefly discussed. The potent role of the subject physicist at the Indian in the development of our understanding of quantum physics Institute of Technology Jodhpur. His major interest is and modern technologies is highlighted. in the field of open quantum systems and also works in the fields of quantum field theory, 1. Introduction quantum optics, and quantum information. Light is intimately connected to the existence of all forms of life. The systematic study of light is known as ‘optics’ and could be traced historically to [1]. The notion of light as an electromag- netic field was made clear by Maxwell, resulting in his cele- brated work on what is now known as Maxwell equations. He showed that electromagnetic fields in vacuum propagate at the Arun M Jayannavar is a senior scientist at Institute of speed of light. The next step in the history of this subject were Physics, Bhubaneswar. He is the questions raised by the Michelson–Morley experiment and interested in general the Rayleigh–Jeans catastrophe associated with black-body radi- condensed matter physics and ation. The former lead to the development of the special theory emergent phenomena. of relativity and the later to Planck’s resolution, which provided the first seeds for the field of quantum mechanics. The notion of Keywords photon, essentially considering it as a particle, was first realized Quantum optics, metamaterials, plasmonics, optomechanical sys- ff in Einstein’s work on the photoelectric e ect. tems, parity-time symmetry. A large number of phenomena, related to optics, could be ex- ∗Vol.25, No.11, DOI: https://doi.org/10.1007/s12045-020-1075-y RESONANCE | November 2020 1559 GENERAL ARTICLE plained by invoking the concept of photons involving a classical electromagnetic field along with vacuum fluctuations. It was soon realized, in the wake of experimental developments that to under- stand the full potential of the photon, one needs to treat it quan- tum mechanically. This lead to the development of the quantum theory of radiation, which in turn, was the precursor to quantum optics [2]. The photon provides an example of a simple quantum state labelled by, say, its horizontal and vertical polarizations as: |ψi = c1 |Hi + c2 |Vi . Here, |ψi, pronounced as ket psi, denotes the state of the sys- tem and is a vector and is an example of a superposition state. Also, c1 and c2 are in general, complex numbers such that the 2 2 sum of squares of their modulus |c1| + |c2| = 1. The states |Hi 2 2 and |Vi can exist simultaneously with probabilities |c1| and |c2| , respectively. This is the surprising content of quantum mechan- In quantum mechanics, ics that makes it stand apart from classical physics. This feature we deal with operators can be used as a resource for achieving things not possible in the characterizing the classical realms. Further, it should be noted that in quantum me- observables. For example, energy is chanics, we deal with operators characterizing the observables. represented by the For example, energy is represented by the operator Hˆ called the operator Hˆ called the Hamiltonian of the system. Experiments typically involve mak- Hamiltonian of the ing measurements of the operator on the state vector and what is system. Experiments typically involve making obtained as a result of the measurement is the eigenvalue of the measurements of the operator. A simple example of measurement would be a projec- operator on the state tion operator that acts on the state of the system to be measured vector and what is and take it to the final state. A basic tenet of quantum mechanics obtained as a result of the measurement is the is that the results of the process of measurement are probabilistic eigenvalue of the in nature, and is known as the Born rule. operator. Quantum measurements are described, in general, by a collec- tion {Mm} of measurement operators, acting on the state space of the system being measured. The index m refers to the mea- surement outcomes that may occur in the experiment. If the state of the quantum system is |ψii immediately before the measure- † ment, then the probability that result m occurs is hψi|Mm Mm|ψii. 1560 RESONANCE | November 2020 GENERAL ARTICLE † Here, hψi|Mm is the Hermitian conjugate of the vector Mm|ψii. The measurement leaves the system in the state: Mm |ψii |ψii → |ψ f i = . (1) † hψi|MmMm|ψii q The measurement operators satisfy the completeness condition † m Mm Mm = ½, expressing the fact that probabilities sum up to one. For those operators M where M† = M and M2 = M , P m m m m m this reduces to the projection operators mentioned above. Quantum optics provide tools to study the foundations of quan- Quantum optics provide tum mechanics with precision and is the cause of several devel- tools to study the opments in quantum information and quantum technology. An foundations of quantum mechanics with important development in quantum optics came with the formu- precision and is the lation of coherent states [3, 4], which basically ask the question cause of several of what are the states of the field that most nearly describes a developments in classical electromagnetic field. This was originally introduced by quantum information and quantum technology. Schrödinger [5]. Classically, electromagnetic field has a well- defined amplitude and phase, a picture that changes in the quan- tum mechanical scenario. A field in a coherent state is a minimum- uncertainty state with equal uncertainties in the two variables, in this context, often termed as the two quadrature components. For example, this could relate to the standard deviation of two sets of operators, such as position and momentum. This was followed by the development of squeezed states, where fluctuations in one quadrature component are reduced below that of the correspond- ing coherent state. In the quest for characterizing the nonclassical behavior of pho- tons, anti-bunching and sub-Poissonian statistics were investigated. The coherent field is represented by Poissonian photon statistics, in which the photons tend to distribute themselves uniformly, i.e., the variance of the photon distribution is equal to its mean. In con- trast to this, in sub-Poissonian statistics, the variance is less than the mean and was, first experimentally demonstrated in [6]. The deviation from Poissonian statistics is quantified by the Mandel QM parameter, discussed below in the context of quantum cor- RESONANCE | November 2020 1561 GENERAL ARTICLE relations. A closely related albeit distinct phenomenon is that of photon antibunching. Photon bunching is the tendency of photons to distribute themselves in bunches, such that when light falls on a photodetector, more photon pairs are detected close together in time than further apart. In contrast to this, in antibunching, the probability of photon pairs detection further apart is greater than that for pairs close together. Both the phenomena of sub- Poissonian statistics and photon antibunching are purely quantum in nature. A major technological development due to quantum optics has been the development of LASER (Light Amplification by Stim- ulated Emission of Radiation), where coherent states play an es- Quantum entanglement, sential role. Quantum entanglement, which is the quintessence of which is the the quantum world, has been experimentally demonstrated with quintessence of the photons and has proved to be a potential resource in quantum quantum world, has been experimentally computation and communication. Spontaneous Parametric Down demonstrated with Conversion (SPDC) is a frequently used process in quantum op- photons and has proved tics, which is very useful for generating squeezed states, single to be a potential resource and entangled photons. in quantum computation and communication. Having sketched the roots of quantum optics, we will, in the re- maining part of this article, try to provide a flavor for some of the modern developments in the field. In this context, the fol- lowing topics will be discussed: (a) atom-field interactions, (b) quantum state engineering, (c) metamaterials and plasmonics, (d) optomechanical systems, (e) PT (Parity-Time) symmetry in quan- tum optics, (f) quasi-probability distributions and quantum state tomography, and (g) topological photonics. 2. Atom-Field Interactions A canonical model of quantum optics is the Rabi model, which deals with the response of an atom to an applied field in resonance with the atom’s natural frequency. Rabi considered the problem of a spin-half magnetic dipole undergoing precessions in a mag- netic field. He obtained the probability of a spin-half atom flip- ping from |0i = (1 0)T or |1i = (0 1)T to the states |1i or |0i, 1562 RESONANCE | November 2020 GENERAL ARTICLE respectively, by an applied radio-frequency magnetic field. Here, T stands for the transpose of the row matrix. In the context of quantum optics, Rabi oscillations would imply oscillations of the atom, considered as a two-level system, between the upper and lower levels under the influence of the electromagnetic field. The Rabi model led to the development of the well-known Jaynes– Cumming model, which is a generalization of the semi-classical Rabi model in the sense that it invokes the interaction of the atom and the single mode of the electromagnetic field in a cavity.
Load more

Recommended publications
  • Nori, Franco; Et Al. Source: PHYSICAL REVIEW B Volume: 87 Issue: 23 Article Number: 235410 DOI: 10.1103/Physrevb.87.235410 Published: JUN 10 2013
    Title: Quantum metamaterial without local control Author(s): Shvetsov, A.; Satanin, A. M.; Nori, Franco; et al. Source: PHYSICAL REVIEW B Volume: 87 Issue: 23 Article Number: 235410 DOI: 10.1103/PhysRevB.87.235410 Published: JUN 10 2013 Title: Full Numerical Simulations of Dynamical Response in Superconducting Single-Photon Detectors Author(s): Ota, Yukihiro; Kobayashi, Keita; Machida, Masahiko; et al. Source: IEEE TRANSACTIONS ON APPLIED SUPERCONDUCTIVITY Volume: 23 Issue: 3 Article Number: 2201105 DOI: 10.1109/TASC.2013.2248871 Part: 1 Published: JUN 2013 Title: Quantum anti-Zeno effect without wave function reduction Author(s): Ai, Qing; Xu, Dazhi; Yi, Su; et al. Source: SCIENTIFIC REPORTS Volume: 3 Article Number: 1752 DOI: 10.1038/srep01752 Published: MAY 8 2013 Title: Hybrid quantum circuit consisting of a superconducting flux qubit coupled to a spin ensemble and a transmission-line resonator Author(s): Xiang, Ze-Liang; Lu, Xin-You; Li, Tie-Fu; et al. Source: PHYSICAL REVIEW B Volume: 87 Issue: 14 Article Number: 144516 DOI: 10.1103/PhysRevB.87.144516 Published: APR 29 2013 Title: Hybrid quantum circuits: Superconducting circuits interacting with other quantum systems Author(s): Xiang, Ze-Liang; Ashhab, Sahel; You, J. Q.; et al. Source: REVIEWS OF MODERN PHYSICS Volume: 85 Issue: 2 Pages: 623-653 DOI: 10.1103/RevModPhys.85.623 Published: APR 9 2013 Title: Nonclassical microwave radiation from the dynamical Casimir effect Author(s): Johansson, J. R.; Johansson, G.; Wilson, C. M.; et al. Source: PHYSICAL REVIEW A Volume: 87 Issue: 4 Article Number: 043804 DOI: 10.1103/PhysRevA.87.043804 Published: APR 4 2013 Title: QuTiP 2: A Python framework for the dynamics of open quantum systems Author(s): Johansson, J.
    [Show full text]
  • Quantum Metamaterials in the Microwave and Optical Ranges Alexandre M Zagoskin1,2* , Didier Felbacq3 and Emmanuel Rousseau3
    Zagoskin et al. EPJ Quantum Technology (2016)3:2 DOI 10.1140/epjqt/s40507-016-0040-x R E V I E W Open Access Quantum metamaterials in the microwave and optical ranges Alexandre M Zagoskin1,2* , Didier Felbacq3 and Emmanuel Rousseau3 *Correspondence: [email protected] Abstract 1Department of Physics, Loughborough University, Quantum metamaterials generalize the concept of metamaterials (artificial optical Loughborough, LE11 3TU, United media) to the case when their optical properties are determined by the interplay of Kingdom quantum effects in the constituent ‘artificial atoms’ with the electromagnetic field 2Theoretical Physics and Quantum Technologies Department, Moscow modes in the system. The theoretical investigation of these structures demonstrated Institute for Steel and Alloys, that a number of new effects (such as quantum birefringence, strongly nonclassical Moscow, 119049, Russia states of light, etc.) are to be expected, prompting the efforts on their fabrication and Full list of author information is available at the end of the article experimental investigation. Here we provide a summary of the principal features of quantum metamaterials and review the current state of research in this quickly developing field, which bridges quantum optics, quantum condensed matter theory and quantum information processing. 1 Introduction The turn of the century saw two remarkable developments in physics. First, several types of scalable solid state quantum bits were developed, which demonstrated controlled quan- tum coherence in artificial mesoscopic structures [–] and eventually led to the devel- opment of structures, which contain hundreds of qubits and show signatures of global quantum coherence (see [, ] and references therein). In parallel, it was realized that the interaction of superconducting qubits with quantized electromagnetic field modes re- produces, in the microwave range, a plethora of effects known from quantum optics (in particular, cavity QED) with qubits playing the role of atoms (‘circuit QED’, [–]).
    [Show full text]
  • Redefining Metrics in Near-Term Devices for Quantum Information
    Mo01 Redefining metrics in near-term devices for quantum information processing Antonio C´orcoles IBM E-mail: [email protected] The outstanding progress in experimental quantum computing over the last couple of decades has pushed multi-qubit gate error rates in some platforms well below 1%. How- ever, as the systems have grown in size and complexity so has the richness of the inter- actions within them, making the meaning of gate fidelity fade when taken isolated from its environment. In this talk I will discuss this topic and offer alternatives to benchmark the performance of small quantum processors for near-term applications. Mo02 Efficient simulation of quantum error correction under coherent error based on non-unitary free-fermionic formalism Yasunari Suzuki1,2, Keisuke Fujii3,4, and Masato Koashi1,2 1Department of Applied Physics, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan 2Photon Science Center, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan 3 Department of Physics, Graduate School of Science, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto, 606-8502, Japan 4JST, PRESTO, 4-1-8 Honcho, Kawaguchi, Saitama, 332-0012, Japan In order to realize fault-tolerant quantum computation, tight evaluation of error threshold under practical noise models is essential. While non-Clifford noise is ubiquitous in experiments, the error threshold under non-Clifford noise cannot be efficiently treated with known approaches. We construct an efficient scheme for estimating the error threshold of one-dimensional quantum repetition code under non-Clifford noise[1].
    [Show full text]
  • Electromagnetic Waves in Josephson Qubit Lines
    Phys. Status Solidi B 246, No. 5, 955–960 (2009) / DOI 10.1002/pssb.200881568 p s sb solidi status www.pss-b.com physica Quantum metamaterials: basic solid state physics Electromagnetic waves in Josephson qubit lines A. M. Zagoskin1,2,3*, A. L. Rakhmanov1,4, Sergey Savel’ev1,2, and Franco Nori1,5 1 Frontier Research System, The Institute of Physical and Chemical Research (RIKEN), Wako-shi, Saitama, 351-0198, Japan 2 Department of Physics, Loughborough University, Loughborough LE11 3TU, United Kingdom 3 Physics and Astronomy Department, The University of British Columbia, Vancouver, B.C., V6T 1Z1, Canada 4 Institute for Theoretical and Applied Electrodynamics RAS, 125412 Moscow, Russia 5 Department of Physics, Center for Theoretical Physics, Applied Physics Program, Center for the Study of Complex Systems, University of Michigan, Ann Arbor, MI 48109-1040, USA Received 15 October 2008, revised 4 February 2009, accepted 4 February 2009 Published online 3 April 2009 PACS 03.67.–a, 41.20.Jb, 82.25.Cp ∗ Corresponding author: e-mail [email protected] We consider the propagation of a classical electromagnetic oscillating bandgap. Similar behaviour is expected from a wave through a transmission line, formed by identical super- transmission line formed by flux qubits. The key ingredient conducting charge qubits inside a superconducting resonator. of these effects is that the optical properties of the Josephson Since the qubits can be in a coherent superposition of quan- transmission line are controlled by the quantum coherent state tum states, we show that such a system demonstrates interest- of the qubits. ing new effects, such as a “breathing” photonic crystal with an © 2009 WILEY-VCH Verlag GmbH & Co.
    [Show full text]
  • Magnetically Induced Transparency of a Quantum Metamaterial Composed of Twin flux Qubits
    ARTICLE DOI: 10.1038/s41467-017-02608-8 OPEN Magnetically induced transparency of a quantum metamaterial composed of twin flux qubits K.V. Shulga 1,2,3,E.Il’ichev4, M.V. Fistul 2,5, I.S. Besedin2, S. Butz1, O.V. Astafiev2,3,6, U. Hübner 4 & A.V. Ustinov1,2 Quantum theory is expected to govern the electromagnetic properties of a quantum metamaterial, an artificially fabricated medium composed of many quantum objects acting as 1234567890():,; artificial atoms. Propagation of electromagnetic waves through such a medium is accompanied by excitations of intrinsic quantum transitions within individual meta-atoms and modes corresponding to the interactions between them. Here we demonstrate an experiment in which an array of double-loop type superconducting flux qubits is embedded into a microwave transmission line. We observe that in a broad frequency range the transmission coefficient through the metamaterial periodically depends on externally applied magnetic field. Field-controlled switching of the ground state of the meta-atoms induces a large suppression of the transmission. Moreover, the excitation of meta-atoms in the array leads to a large resonant enhancement of the transmission. We anticipate possible applications of the observed frequency-tunable transparency in superconducting quantum networks. 1 Physikalisches Institut, Karlsruhe Institute of Technology, D-76131 Karlsruhe, Germany. 2 Russian Quantum Center, National University of Science and Technology MISIS, Moscow, 119049, Russia. 3 Moscow Institute of Physics and Technology, Dolgoprudny, 141700 Moscow region, Russia. 4 Leibniz Institute of Photonic Technology, PO Box 100239, D-07702 Jena, Germany. 5 Center for Theoretical Physics of Complex Systems, Institute for Basic Science, Daejeon, 34051, Republic of Korea.
    [Show full text]
  • Dispersive Response of a Disordered Superconducting Quantum Metamaterial
    Photonics 2015, 2, 449-458; doi:10.3390/photonics2020449 OPEN ACCESS photonics ISSN 2304-6732 www.mdpi.com/journal/photonics Article Dispersive Response of a Disordered Superconducting Quantum Metamaterial Dmitriy S. Shapiro 1;2;3;*, Pascal Macha 4;5, Alexey N. Rubtsov 1;3 and Alexey V. Ustinov 1;4;6 1 Russian Quantum Center, Novaya St. 100, Skolkovo, Moscow region 143025, Russia; E-Mail: [email protected] (A.N.R.); [email protected] (A.V.U.) 2 Kotel’nikov Institute of Radio Engineering and Electronics of the Russian Academie of Sciences, Mokhovaya 11/7, Moscow 125009, Russia 3 Center of Fundamental and Applied Research, N.L. Dukhov All-Russia Institute of Science and Research, Sushchevskaya 22, Moscow 123055, Russia 4 Physikalisches Institut, Karlsruhe Institute of Technology, Karlsruhe D-76128, Germany; E-Mail: [email protected] 5 ARC Centre for Engineered Quantum Systems, University of Queensland, Brisbane, Queensland 4072, Australia 6 National University of Science and Technology MISIS, Leninsky prosp. 4, Moscow 119049, Russia * Author to whom correspondence should be addressed; E-Mail: [email protected]; Tel.: +7-495-629-34-59 Received: 8 April 2015 / Accepted: 23 April 2015 / Published: 27 April 2015 Abstract: We consider a disordered quantum metamaterial formed by an array of superconducting flux qubits coupled to microwave photons in a cavity. We map the system on the Tavis-Cummings model accounting for the disorder in frequencies of the qubits. The complex transmittance is calculated with the parameters taken from state-of-the-art experiments. We demonstrate that photon phase shift measurements allow to distinguish individual resonances in the metamaterial with up to 100 qubits, in spite of the decoherence spectral width being remarkably larger than the effective coupling constant.
    [Show full text]
  • Quantum Engineering
    QUANTUM ENGINEERING Quantum engineering – the design and fabrication of quantum coherent structures – has emerged as a field in physics with important potential applications. This book provides a self-contained presentation of the theoretical methods and experimental results in quantum engineering. The book covers such topics as the quantum theory of electric circuits; theoretical methods of quantum optics in application to solid-state circuits; the quantum theory of noise, decoherence and measurements; Landauer formalism for quantum trans- port; the physics of weak superconductivity; and the physics of a 2-dimensional electron gas in semiconductor heterostructures. The theory is complemented by up-to-date experimental data to help put it into context. Aimed at graduate students in physics, the book will enable readers to start their own research and apply the theoretical methods and results to their current experimental situation. a. m. zagoskin is a Lecturer in Physics at Loughborough University, UK. His research interests include the theory of quantum information processing in solid-state devices, mesoscopic superconductivity, mesoscopic transport, quantum statistical physics and thermodynamics. QUANTUM ENGINEERING Theory and Design of Quantum Coherent Structures A. M. ZAGOSKIN Loughborough University cambridge university press Cambridge, New York, Melbourne, Madrid, Cape Town, Singapore, São Paulo, Delhi, Tokyo, Mexico City Cambridge University Press The Edinburgh Building, Cambridge CB2 8RU, UK Published in the United States of America by Cambridge University Press, New York www.cambridge.org Informationonthistitle:www.cambridge.org/9780521113694 © A. M. Zagoskin 2011 This publication is in copyright. Subject to statutory exception and to the provisions of relevant collective licensing agreements, no reproduction of any part may take place without the written permission of Cambridge University Press.
    [Show full text]
  • Perfect Quantum Metamaterial
    Perfect Quantum Metamaterial Scientists have devised a way to build a "quantum metamaterial"—an engineered material with exotic properties not found in nature—using ultracold atoms trapped in an artificial crystal composed of light. The theoretical work represents a step toward manipulating atoms to transmit information, perform complex simulations or function as powerful sensors. [11] An optical chip developed at INRS by Prof. Roberto Morandotti's team overcomes a number of obstacles in the development of quantum computers, which are expected to revolutionize information processing. An international research team has demonstrated that on-chip quantum frequency combs can be used to simultaneously generate multiphoton entangled quantum bit (qubit) states. [10] Optical photons would be ideal carriers to transfer quantum information over large distances. Researchers envisage a network where information is processed in certain nodes and transferred between them via photons. [9] While physicists are continually looking for ways to unify the theory of relativity, which describes large-scale phenomena, with quantum theory, which describes small-scale phenomena, computer scientists are searching for technologies to build the quantum computer using Quantum Information. In August 2013, the achievement of "fully deterministic" quantum teleportation, using a hybrid technique, was reported. On 29 May 2014, scientists announced a reliable way of transferring data by quantum teleportation. Quantum teleportation of data had been done before but with highly unreliable methods. The accelerating electrons explain not only the Maxwell Equations and the Special Relativity, but the Heisenberg Uncertainty Relation, the Wave-Particle Duality and the electron’s spin also, building the Bridge between the Classical and Quantum Theories.
    [Show full text]
  • Frontiers of Quantum and Mesoscopic Thermodynamics 14 - 20 July 2019, Prague, Czech Republic
    Frontiers of Quantum and Mesoscopic Thermodynamics 14 - 20 July 2019, Prague, Czech Republic Under the auspicies of Ing. Miloš Zeman President of the Czech Republic Jaroslav Kubera President of the Senate of the Parliament of the Czech Republic Milan Štˇech Vice-President of the Senate of the Parliament of the Czech Republic Prof. RNDr. Eva Zažímalová, CSc. President of the Czech Academy of Sciences Dominik Cardinal Duka OP Archbishop of Prague Supported by • Committee on Education, Science, Culture, Human Rights and Petitions of the Senate of the Parliament of the Czech Republic • Institute of Physics, the Czech Academy of Sciences • Department of Physics, Texas A&M University, USA • Institute for Theoretical Physics, University of Amsterdam, The Netherlands • College of Engineering and Science, University of Detroit Mercy, USA • Quantum Optics Lab at the BRIC, Baylor University, USA • Institut de Physique Théorique, CEA/CNRS Saclay, France Topics • Non-equilibrium quantum phenomena • Foundations of quantum physics • Quantum measurement, entanglement and coherence • Dissipation, dephasing, noise and decoherence • Many body physics, quantum field theory • Quantum statistical physics and thermodynamics • Quantum optics • Quantum simulations • Physics of quantum information and computing • Topological states of quantum matter, quantum phase transitions • Macroscopic quantum behavior • Cold atoms and molecules, Bose-Einstein condensates • Mesoscopic, nano-electromechanical and nano-optical systems • Biological systems, molecular motors and
    [Show full text]
  • Renninger's Gedankenexperiment, the Collapse of the Wave Function in a Rigid Quantum Metamaterial and the Reality of the Quant
    View metadata, citation and similar papers at core.ac.uk brought to you by CORE www.nature.com/scientificreportsprovided by Loughborough University Institutional Repository OPEN Renninger’s Gedankenexperiment, the collapse of the wave function in a rigid quantum metamaterial and Received: 14 August 2015 Accepted: 6 June 2018 the reality of the quantum state Published: xx xx xxxx vector Sergey E. Savel’ev 1 & Alexandre M. Zagoskin1,2 A popular interpretation of the “collapse” of the wave function is as being the result of a local interaction (“measurement”) of the quantum system with a macroscopic system (“detector”), with the ensuing loss of phase coherence between macroscopically distinct components of its quantum state vector. Nevetheless as early as in 1953 Renninger suggested a Gedankenexperiment, in which the collapse is triggered by non-observation of one of two mutually exclusive outcomes of the measurement, i.e., in the absence of interaction of the quantum system with the detector. This provided a powerful argument in favour of “physical reality” of (nonlocal) quantum state vector. In this paper we consider a possible version of Renninger’s experiment using the light propagation through a birefringent quantum metamaterial. Its realization would provide a clear visualization of a wave function collapse produced by a “non-measurement”, and make the concept of a physically real quantum state vector more acceptable. Te central element of the transition from quantum to classical behaviour (e.g., during the measurement) is the loss of phase coherence between the components of the wave function corresponding to macroscopically dis- tinguishable states of the system1.
    [Show full text]
  • Quantum Information Processing with Superconducting Circuits: a Review
    Quantum Information Processing with Superconducting Circuits: a Review G. Wendin Department of Microtechnology and Nanoscience - MC2, Chalmers University of Technology, SE-41296 Gothenburg, Sweden Abstract. During the last ten years, superconducting circuits have passed from being interesting physical devices to becoming contenders for near-future useful and scalable quantum information processing (QIP). Advanced quantum simulation experiments have been shown with up to nine qubits, while a demonstration of Quantum Supremacy with fifty qubits is anticipated in just a few years. Quantum Supremacy means that the quantum system can no longer be simulated by the most powerful classical supercomputers. Integrated classical-quantum computing systems are already emerging that can be used for software development and experimentation, even via web interfaces. Therefore, the time is ripe for describing some of the recent development of super- conducting devices, systems and applications. As such, the discussion of superconduct- ing qubits and circuits is limited to devices that are proven useful for current or near future applications. Consequently, the centre of interest is the practical applications of QIP, such as computation and simulation in Physics and Chemistry. Keywords: superconducting circuits, microwave resonators, Josephson junctions, qubits, quantum computing, simulation, quantum control, quantum error correction, superposition, entanglement arXiv:1610.02208v2 [quant-ph] 8 Oct 2017 Contents 1 Introduction 6 2 Easy and hard problems 8 2.1 Computational complexity . .9 2.2 Hard problems . .9 2.3 Quantum speedup . 10 2.4 Quantum Supremacy . 11 3 Superconducting circuits and systems 12 3.1 The DiVincenzo criteria (DV1-DV7) . 12 3.2 Josephson quantum circuits . 12 3.3 Qubits (DV1) .
    [Show full text]
  • Quantum Metamaterial for Broadband Detection of Single Microwave Photons
    PHYSICAL REVIEW APPLIED 15, 034074 (2021) Quantum Metamaterial for Broadband Detection of Single Microwave Photons Arne L. Grimsmo ,1,2,* Baptiste Royer ,1,3 John Mark Kreikebaum,4,5 Yufeng Ye,6,7 Kevin O’Brien,6,7 Irfan Siddiqi,4,5,8 and Alexandre Blais 1,9 1 Institut quantique and Départment de Physique, Université de Sherbrooke, Sherbrooke, Québec J1K 2R1, Canada 2 Centre for Engineered Quantum Systems, School of Physics, The University of Sydney, Sydney, Australia 3 Department of Physics, Yale University, New Haven, Connecticut 06520, USA 4 Materials Science Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA 5 Quantum Nanoelectronics Laboratory, Department of Physics, University of California, Berkeley, California 94720, USA 6 Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA 7 Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA 8 Computational Research Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA 9 Canadian Institute for Advanced Research, Toronto, Canada (Received 14 July 2020; revised 27 January 2021; accepted 1 February 2021; published 25 March 2021) Detecting traveling photons is an essential primitive for many quantum-information processing tasks. We introduce a single-photon detector design operating in the microwave domain, based on a weakly nonlinear metamaterial where the nonlinearity is provided by a large number of Josephson junctions. The combination of weak nonlinearity and large spatial extent circumvents well-known obstacles limiting approaches based on a localized Kerr medium. Using numerical many-body simulations we show that the single-photon detection fidelity increases with the length of the metamaterial to approach one at experi- mentally realistic lengths.
    [Show full text]