************************************ * QUANTUM OPTICS AND ATOM OPTICS * * IN AUSTRALASIA * * * * * * * * MONTHLY NEWSLETTER * * VOL XI, NO 2 * * * CONTENTS: * February 2003 * * * 0. EDITORIAL NOTE * ISSN 1325-6467 * Edited by: 1. ABSTRACTS * * Alexei Gilchrist 2. VACANCIES * \ | / * Physics, University of Queensland, 3. BUY/SELL * \__|__/ * QLD 4072, Australia. 4. MISC NEWS * | * email: alexei@physics.uq.edu.au 5. CONFERENCES * | * phone: +61 7 3365 2422 * | * fax: +61 7 3365 1242 Available on WWW at: * * http://www.physics.uq.edu.au/qonews =============================================================================== 1. ABSTRACTS =============================================================================== Quantum Trajectories and Quantum Measurement Theory H. M. Wiseman quant-ph/0302080 Beyond their use as numerical tools, quantum trajectories can be ascribed a degree of reality in terms of quantum measurement theory. In fact, they arise naturally from considering continuous observation of a damped quantum system. A particularly useful form of quantum trajectories is as linear (but non-unitary) stochastic Schrodinger equations. In the limit where a strong local oscillator is used in the detection, and where the system is not driven, these quantum trajectories can be solved. This gives an alternate derivation of the probability distributions for completed homodyne and heterodyne detection schemes. It also allows the previously intractable problem of real-time adaptive measurements to be treated. The results for an analytically soluble example of adaptive phase measurements are presented, and future developments discussed. ---------------------------------------------------------------------- Semigroup techniques for the efficient classical simulation of optical quantum information Stephen D. Bartlett quant-ph/0302063 A framework to describe a broad class of physical operations (including unitary transformations, dissipation, noise, and measurement) in a quantum optics experiment is given. This framework provides a powerful tool for assessing the capabilities and limitations of performing quantum information processing tasks using current experimental techniques. The Gottesman-Knill theorem is generalized to the infinite-dimensional representations of the group stabilizer formalism and further generalized to include non-invertable semigroup transformations, providing a theorem for the efficient classical simulation of operations within this framework. As a result, we place powerful constraints on obtaining computational speedups using current techniques in quantum optics. ---------------------------------------------------------------------- Spin squeezing and pairwise entanglement for symmetric multiqubit states Xiaoguang Wang, Barry C. Sanders quant-ph/0302014 We show that spin squeezing implies pairwise entanglement for arbitrary symmetric multiqubit states, and give a quantitative relation between the squeezing parameter and the concurrence for even and odd states, which refer to states with even or odd excitations. We prove that the even states generated from the one-axis twisting Hamiltonian are spin squeezed if and only if they are pairwise entangled; i.e., spin squeezing and pairwise entanglement are equivalent for these states. Numerical results show that this equivalence relation also holds for the one-axis twisting Hamiltonian with an external transverse field and for the two-axis counter-twisting Hamiltonian. ---------------------------------------------------------------------- Quantum error correction for continuously detected errors Charlene Ahn, H. W. Wiseman, G. J. Milburn quant-ph/0302006 We show that quantum feedback control can be used as a quantum error correction process for errors induced by weak continuous measurement. In particular, when the error model is restricted to one, perfectly measured, error channel per physical qubit, quantum feedback can act to perfectly protect a stabilizer codespace. Using the stabilizer formalism we derive an explicit scheme, involving feedback and an additional constant Hamiltonian, to protect an ($n-1$)-qubit logical state encoded in $n$ physical qubits. This works for both Poisson (jump) and white-noise (diffusion) measurement processes. In addition, universal quantum computation is possible in this scheme. As an example, we show that detected-spontaneous emission error correction with a driving Hamiltonian can greatly reduce the amount of redundancy required to protect a state from that which has been previously postulated [e.g., Alber \emph{et al.}, Phys. Rev. Lett. 86, 4402 (2001)]. ---------------------------------------------------------------------- Input states for quantum gates A. Gilchrist, W.J. Munro, A.G. White quant-ph/0301112 We examine three possible implementations of non-deterministic linear optical cnot gates with a view to an in-principle demonstration in the near future. To this end we consider demonstrating the gates using currently available sources such as spontaneous parametric down conversion and coherent states, and current detectors only able to distinguish between zero or many photons. The demonstration is possible in the co-incidence basis and the errors introduced by the non-optimal input states and detectors are analysed. ---------------------------------------------------------------------- How robust is a quantum gate in the presence of noise? Aram W. Harrow, Michael A. Nielsen quant-ph/0301108 We define several quantitative measures of the robustness of a quantum gate against noise. Exact analytic expressions for the robustness against depolarizing noise are obtained for all unitary quantum gates, and it is found that the controlled-not is the most robust two-qubit quantum gate, in the sense that it is the quantum gate which can tolerate the most depolarizing noise and still generate entanglement. Our results enable us to place several analytic upper bounds on the value of the threshold for quantum computation, with the best bound in the most pessimistic error model being 0.5. =============================================================================== 2. VACANCIES =============================================================================== Research Assistant in Experimental Quantum Information (Two posts) (ref. 9118) University of Bristol, Department of Electrical & Electronic Engineering The Department of Electrical and Electronic Engineering is assembling a world-leading experimental group in quantum information and communications. This group is co-ordinator of the EU programme RAMBOQ and will have strong links into the UK Quantum Information IRC. Areas to be studied are: single photon sources and detectors, multi-quantum interference, quantum communication and linear optics quantum logic. You will be responsible for building and developing various experimental capabilities including pair photon sources, photon counting systems, micro-PL equipments, optical cryostats and general polarisation optics and interferometry. Candidates with experience in one or more of these areas are encouraged to apply. The initial contract will be for 12 months in the first instance Further details and an application form can be found at http://www.bris.ac.uk/boris/jobs/ads?ID=9148 Contact for informal enquiries : Professor JG Rarity john.rarity@bristol.ac.uk Tel. 0117 954 5646 Alternatively you can telephone (0117) 954 6947, minicom (0117) 928 8894 or E-Mail Recruitment@bris.ac.uk (stating postal address ONLY), quoting reference number 9118. The closing date for applications is 9.00am, 05 March 2003
An Equal Opportunities Employer. ------------------------------------------------------------------------------- ADVERTISEMENT FOR CANADA RESEARCH CHAIR AT THE UNIVERSITY OF CALGARY http://careers.peopleclick.com/jobposts/Client40_UofC/BU1/External/32-1479.htm Job ID #:1504 Title:Department of Physics and Astronomy The Department of Physics and Astronomy at the University of Calgary invites applications from outstanding candidates in experimental atomic, molecular, and optical (AMO) physics for nomination to a Tier II Canada Research Chair (CRC) in Experimental Quantum Information Science. The Canada Research Chairs Programme has been established by the Canadian government to enable Canadian universities to foster research excellence and enhance their role as world class centres of research. Further information on the CRC programme may be found at http://www.chairs.gc.ca. This assistant professorship is part of the University's expansion in quantum information science, which includes the disciplines of experimental and theoretical physics in addition to computer science. As of September 2003, the Department will be the home of a new research group in quantum information science, supported by the Alberta Informatics Circle of Research Excellence (iCORE) program. The new faculty member will have the opportunity to interact closely with dynamic research groups in the Department of Computer Science currently investigating fundamental issues in quantum algorithms, complexity theory, and cryptography, and with current members of the AMO group in the Department of Physics and Astronomy, whose current activities include ion cooling and trapping, high resolution spectroscopy, and degenerate dilute atomic gases. Prospective candidates are encouraged to visit www.cpsc.ucalgary.ca/Research/quantum. The successful candidate must have a Ph.D. and postdoctoral experience or equivalent in experimental physics, an excellent track record in experimental physics research, an ability to establish and maintain an outstanding research program in quantum information science, and a strong commitment to teaching excellence. Applications with curriculum vitae (including a full list of publications, statements of research, and teaching goals) and four letters of reference should be sent to: Chair, Search Committee; Experimental Quantum Information Science; Department of Physics and Astronomy; University of Calgary, Calgary, AB, Canada T2N 1N4; E-mail: jcarr@ucalgary.ca; Telephone: (403) 220-3293; Fax: (403) 282-9154. The deadline for applications is May 15, 2003. Nomination to the CRC Program will occur in September 2003, and the anticipated start date is July 1, 2004. The University of Calgary respects, appreciates and encourages diversity. PLEASE DO NOT APPLY ONLINE, AS WE ARE NOT ACCEPTING ONLINE APPLICATIONS FOR TEACHING OR RESEARCH POSITIONS AT THIS TIME. THANK YOU FOR YOUR COOPERATION. =============================================================================== 5. CONFERENCES / WORKSHOPS =============================================================================== Obergurgl Meeting: Quantum optics 23 February-1 March 2003 Deadline: 1 December, 2002 Obergurgl, Austria. http://th-physik.uibk.ac.at/qo/obergurgl/ This meeting will cover different aspects of Quantum Optics. ------------------------------------------------------------------- 3rd ESF meeting - Quantum Information Theory and Quantum Computing 15th-22nd March 2003 registration deadline: 24th December 2002 Ettore Majorana Center in Erice, Italy. http://www.lsr.ph.ic.ac.uk/~plenio/erice2003/erice2003c.html The meeting follows earlier successful programme meetings held in Cambridge in 1999 and Gdansk in 2001 and will focus on "Advances in quantum information processing: from theory to experiments". ------------------------------------------------------------------- GRC conference on Quantum Information Science March 23-28, 2003 Ventura, California. http://www.grc.org/programs/2003/quantinf.htm Quantum Information Science will be a yearly conference focusing on the rapidly growing field of Quantum Information Processing. The primary focus of the conference will be on physical and theoretical aspects that arise in implementation of quantum information processing for computation or communication. The conference will bring together researchers from the diverse fields of physics, computer science, mathematics, chemistry, materials science, and engineering, with the common interest of increasing our understanding of how to formulate, manipulate, and process information using physical systems that operate on quantum mechanical principles. ------------------------------------------------------------------- Fluctuations and Noise 2003 1-4 June 2003 Abstract Due: 25 November 2002 Santa Fe, New Mexico USA http://spie.org/Conferences/Calls/03/fn/ Containing six parallel conferences: * Fluctuations and Noise in Biological, Biophysical, and Biomedical Systems * Fluctuations and Noise in Photonics and Quantum Optics * Noise as a Tool for Studying Materials * Noise in Devices and Circuits * Noise in Complex Systems and Stochastic Dynamics * Noise and Information in Nano-electronics, Sensors, and Standards ------------------------------------------------------------------- 8th International Conference on Squeezed States and Uncertainty Relations 9-13 June, 2003 Puebla, Mexico http://www-optica.inaoep.mx/ICSSUR/8th.html The program of the Conference will reflect the continuing importance of fundamental quantum physics and the increasing importance of applications in the domain of quantum optics. Contributed experimental and theoretical papers in all of these topics are solicited: o Squeezed states and uncertainty relations o Quantum-state generation and characterization o Phase space and group representations in quantum physics o Quantum transforms in signal analysis and quantum physics o Quantum interference and entanglement o Quantum-like and mesoscopic systems o Foundations of quantum mechanics and quantum optics o Trapped atoms and degenerate gases o Quantum chaos and quantum control o Quantum information and communication o Quantum computing ------------------------------------------------------------------- Benasque Center for Science - Quantum Information 22nd June - 11th July 2003 Deadline for applications is March 15. Barcelona, Spain http://sophia.ecm.ub.es/2003qi/2003qi.htm A three-week Benassque session will be devoted to recent progress in Quantum Information and Communication. Special topics that will be covered during the meeting are: * Theory of Quantum Information,Entanglement, Quantum Algorithms,... QCD * Experiments in Quantum Information, Trapped ions, photons, NMR, Superconducting currents, quantum dots, ------------------------------------------------------------------- Les Houches Summer School on 'Quantum entanglement and information processing' 30 June - 25 July, 2003. Registration deadline: March 7, 2003 Les Houches, France. http://www-houches.ujf-grenoble.fr/index-en.html The recent discovery that the laws of quantum physics could be used for efficient information processing or transmission led to a considerable upsurge of interest in developing a deeper understanding of quantum mechanics, and in fabricating genuine quantum processors. This new field gathers around common objectives various communities, such as theoretical physics, quantum optics or solid state physics. On the theoretical side, the major advances concern quantum algorithms and quantum error correction codes. On the experimental side, significant advances have been realized in quantum optics, solid state physics and nuclear magnetic resonance. In particular, quantum logic gates have been demonstrated, and small-size quantum algorithms have been operated. This school aims to provide a comprehensive overview of the theoretical and experimental aspects of quantum entanglement and information processing. It is opened to young researchers interested in learning the essentials of this new field. Introductory lectures will provide them with a common background, while more specialized lectures and seminars will give an up to date panorama. ------------------------------------------------------------------- ICOLS 03: 16th International Conference on Laser Spectroscopy 13-18 July 2003 Preregistration: 13 December 2002 Earlybird registration and abstracts: 7 April 2003 Palm Cove, AUSTRALIA http://www.swin.edu.au/rescentres/soll/icols03/icols.html Following the tradition of ICOLS conferences, the program will consist of single sessions of invited talks and posters covering the latest developments in Laser Spectroscopy and related topics. Scheduling will allow significant time for informal discussions. The number of participants will be limited to about 250-300. ------------------------------------------------------------------- 4th European QIPC Workshop 13th - 18th July 2003 Submission deadline: 04 April 2003 Oxford, UK http://www.quiprocone.org/4th_Keble.htm The purpose of the workshop is to promote interaction across the broad subject area of QIPC and follows previous meetings in Potsdam, ISI Torino and Trinity College Dublin. ------------------------------------------------------------------- 48th SPIE Meeting: Quantum Communications and Quantum Imaging (AM112) 3-8 August 2003 Abstract Due: 6 January 2003 Manuscript Due: 7 July 2003 http://spie.org/Conferences/Calls/03/am/conferences/index.cfm?fuseaction=AM112 Quantum communications and quantum imaging are emerging technologies that promise great benefits as well as great challenges. The objective of this conference is to provide a forum for researchers and system developers in both fields and encourage technology exchange between the quantum communication and quantum imaging communities. ------------------------------------------------------------------- IWQDQC: The 2nd International Workshop on Quantum Dots for Quantum Computing 7-9 August, 2003 Deadline for abstracts: 15 March 2003 Early registration: 1 July, 2003 University of Notre Dame, Indiana, USA http://www.nd.edu/%7Eiwqdqc/index.html The workshop is intended to be an international forum for discussions on the current trends and future directions of research in quantum dots and solid-state implementations for quantum computing. ------------------------------------------------------------------- Quantum Optics - EuroConference on Cavity QED and Quantum Fluctuations: From Fundamental Concepts to Nano-Technology 27 September - 02 October 2003 Applications by 26 May 2003 Granada, Spain http://www.esf.org/euresco/03/pc03005 Quantum Optics is a very active and fast evolving field in physics with at its core the understanding and control of quantum systems. The objective of the Quantum Optics Euroconferences is to bring together the leading groups in the field with the emphasis on combining knowledge and technology of different subfields and identifying new promising directions. The 2003 Quantum Optics conference will focus on cavity quantum electrodynamics and quantum fluctuations, covering a broad range of topics from fundamental concepts of quantum optics to technological developments. Sessions will be devoted to cavity QED, Casimir forces and their impact in nanostructures, quantum information and decoherence phenomena, coherent atomic sources and BEC in atom chips and wave guides. In close connection with these topics a session will address the new emerging field of nano-optics. ** Addendum ** =============================================================================== 2. VACANCIES =============================================================================== The Cambridge Centre for Quantum Computation The Cambridge Centre for Quantum Computation wishes to appoint one or more postdoctoral researchers in theoretical quantum cryptography. The position or positions are associated with the EU-funded project PROSECCO, which aims to develop new quantum cryptographic protocols and improved security analyses for quantum cryptography. Funds are available till January 2006 and the position or positions are available immediately. Applicants should send a letter of application supported by a full CV and arrange for three reference letters to be sent to: Kaija Hampson, DAMTP, CMS, Wilberforce Road, Cambridge CB3 0WA, email: K.K.Hampson@damtp.cam.ac.uk Tel +44 (0)1223 760 394. Informal enquiries can be made to: Dr Adrian Kent, University Lecturer in Quantum Information, Centre for Quantum Computation, Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, U.K, email: a.p.a.kent@damtp.cam.ac.uk Tel +44 1223 760 379. The closing date: 7 March 2003 Salary in the range £18,265 - £27,339 pa