************************************ * QUANTUM OPTICS AND ATOM OPTICS * * IN AUSTRALASIA * * * * * * * * MONTHLY NEWSLETTER * * VOL IV, NO 4 * * * CONTENTS: * April 1996 * ________________ * * * ISSN 1325-6467 * 1. ABSTRACTS * * Edited by: Craig Savage 2. CONFERENCES * \ | / * Physics, Faculties, ANU, 3. JOB WANTED * \__|__/ * ACT 0200, Australia. * | * email: Craig.Savage@anu.edu.au Available on WWW at: * | * fax: +61 [(0)6] 249 0741 http://www.anu.edu.au * | * voice: +61 [(0)6] 249 4202 /Physics/newsletter * * ___________________ 1. ABSTRACTS ____________ TITLE: Squeezing and antisqueezing in homodyne measurements AUTHORS: M. S. Kim [1] and B. C. Sanders [2] ADDRESS: [1] Dep't of Physics, Sogang University, Seoul [2] School of MPCE and Centre for Lasers and Applications, Macquarie University, Sydney, NSW EMAIL CONTACT: barry@sanders.mpce.mq.edu.au JOURNAL: Physical Review A STATUS: Accepted as a brief report ABSTRACT: Squeezing the signal field or the local oscillator can improve the accuracy of homodyne detection. We show that an equivalence exists between antisqueezing the signal field and squeezing the local oscillator state. The importance of this result is illustrated in two contexts: a homodyne measurement of squeezing and the reconstruction of the wave function. ____________ TITLE: Master Equation Theory of Multi-Mode Semiconducotr Lasers AUTHORS: A. Eschmann and C.W. Gardiner, ADDRESS: University of Waikato, Hamilton, New Zealand. EMAIL CONTACT: andrea@phys.waikato.ac.nz JOURNAL: Phys. Rev. A STATUS: Accepted ABSTRACT: We extend the master equation treatment of the single-mode laser(Gardiner and Eschmann, Phys. Rev. A 51, 4982 (1995)) to include two sub-threshold side modes. We calculate spectra for a wide range of decay constantratios and confirm the predictions found by Marin et al. (Marin et al., Phys. Rev. Lett. 75, 4606 (1995).) ____________ TITLE: Master Equation Theory of Multi-Mode Semiconductor Lasers II: Injection Locking AUTHORS: A. Eschmann, C.W. Gardiner* ADDRESS: University of Waikato, Hamilton, New Zealand. *Victoria University of Wellington, Wellington, New Zealand. EMAIL CONTACT: andrea@phys.waikato.ac.nz JOURNAL: Phys. Rev. A STATUS: Submitted ABSTRACT: The master equation theory for multi-mode semicondcutor lasers (A. Eschmann and C.W. Gardiner, to appear Phys. rev. A, 1995) is adapted to treat the case of an injection locked laser. Both the intensity noise and the phase noise of the system are examined. A decrease in the total intensity noise and in the intensity noises of the individual modes is found for increasing injection power, provided the injection signal does not dominate the entire system. A regime is found in which a reduction of the intensity noise below the shot noise level is obtained which is not single mode squeezing, but which is due to the anti-correlations between the individual modes, and a further regime in which true single mode squeezing exists is also found. The phase noise is found to decrease with increasing injection strength, in other words as phase locking occurs. ____________ TITLE: Quantum noise in optical beam propagation in distributed amplifiers AUTHORS: Min Gyu Kim[1], Nobuyuki Imoto [1,2], Kyuman Cho [1] and Myung Shik Kim [1] ADDRESS: [1] Physics Department, Sogang University, CPO Box 1142, Seoul, 100-611, Korea [2] NTT Basic Research Laboratories, 3-1 Morinosato-Wakamiya, Atsugi-shi, Kanagawa 243-01, Japan EMAIL CONTACT: mshkim@ccs.sogang.ac.kr JOURNAL: Optics Communications STATUS: Accepted (minor modificaion to be done) ABSTRACT: Quantum effects on optical beam propagation in a gain medium having distributed loss is analyzed using an amplifier-attenuator array model. For the amplifier-attenuator set, the Wigner function of the output field is related to that of the input field by a convolution law. Using this, we derive the Fokker-Planck equation for the beam propagation in the distributed amplifier with loss, and the added quantum noise is analyzed by solving the equation. When the amplification just compensates the attenuation, the mean amplitude of the signal does not change but the mean energy grows due to the added noise. Even in this case, the photon number variance can be reduced when a proper phase-sensitive reservoir is incorporated. ____________ TITLE: Nonlocal momentum transfer in welcher Weg schemes AUTHORS: H.M. Wiseman, F.E. Harrison, M.J. Collett, D.F. Walls, S.M. Tan, and R.B. Killip* ADDRESS: Department of Physics,University of Auckland, Auckland, New Zealand *Department of Mathematics, University of Auckland, EMAIL CONTACT: h.wiseman@auckland.ac.nz STATUS: submitted to Phys Rev A. ABSTRACT: A which path (welcher Weg) measurement necessarily destroys the fringes in a double slit interference experiment. We show that this destruction is due to a momentum disturbance of at least $\pi\hbar/(2d)$, where d is the slit separation, in accordance with the uncertainty principle. However this momentum transfer need not be local (that is, at the slits). For well-known welcher Weg measurements such as Einstein's recoiling slit and Feynman's light microscope, the disturbance can be attributed to classical (local) momentum kicks, but in some recent proposals, including that by Scully, Englert and Walther [Nature 35}, 111 (1991)], the momentum disturbance is of a peculiarly quantum, nonlocal, nature. We use the Wigner function formalism, according to which the fringes are destroyed by momentum transfer midway between the slits, and show that for some examples there is absolutely no momentum disturbance at the slits. We also discuss the experimental signatures of local versus nonlocal momentum disturbance, and show the strong similarity with the nonlocality of the Aharonov-Bohm effect. ____________ &&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&& 2. CONFERENCES ________________ Quantum Optics Meeting - Satellite Meeting to IQEC '96 8-9 July 1996 Novotel Palm Cove Resort, Cairns, North Queensland, Australia This two-day meeting on Quantum Optics will be a satellite meeting to IQEC'96. It will take place at Novotel Palm Cove Resort, Cairns, North Queensland on Monday 8 and Tuesday 9 July, in the week before the IQEC Meeting in Sydney (14-19 July). The meeting will overlap with the three-day meeting on Atom Optics to be held at the same venue on Tuesday 9, Wednesday 10 and Thursday 11 July. For more details (including registration form) see http://www.physics.uq.oz.au:8001/conference/welcome.html ________________ Atom Optics Meeting- Satellite Meeting to IQEC '96 9-11 July 1996 Novotel Palm Cove Resort, Cairns, North Queensland, Australia This three-day workshop on Atoms Optics and Interferometry will be a satellite meeting to IQEC `96. The workshop will overlap with the two-day workshop on Quantum Optics to be held at the same venue on Monday 8, and Tuesday 9 July. For more details see: http://www.anu.edu.au/Physics/Cairns96/ &&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&& 3. JOB WANTED ________________ GORDON YEOMAN. I am looking for a postdoctoral position in the fields of quantum mechanics or modern optics (my Ph.D was concerned with squeezed light and resonance fluorescence). I am prepared to tackle a wide range of problems in these areas. Furthermore, I am willing to do research in areas which lie outwith my Ph.D training. Abbreviated CV gordon&phys.strath.ac.uk Education 1991-1994 Ph.d thesis: Squeezed Light and Resonance Flurescence 1987-1991 BSc (Hons) Physics. First Class Honours Research Experience Conducted theoretical investigations of conceptually simple experiments which could be performed using two distinct types of squeezed light. Comprehensively studied the mixing of two single-mode squeezed states at a beam-splitter. Analytically investigated the effect of squeezing bandwidths on resonance fluorescence. Referees Dr. S. M. Barnett Dr. S. Swain Department of Physics, Department of Applied Mathematics University of Strathclyde, and Theoretical Physics, 107 Rottenrow, The Queen's University of Belfast, Glasgow G4 0NG. Belfast, BT7 1NN, Fax: 0141 552 2891 Fax:01232 239182 Publications G. Yeoman and Stephen. M. Barnett. Two-Mode Squeezed Gaussons, J. Mod. Optics, vol40 1497 (1993). G. Yeoman and Stephen. M. Barnett. Influence of Squeezing Bandwidths on Resonance Fluorescence, accepted for publication in J. Mod. Optics. &&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&