************************************ * QUANTUM OPTICS AND ATOM OPTICS * * IN AUSTRALASIA * * * * * * * * MONTHLY NEWSLETTER * * VOL IV, NO 5 * * * CONTENTS: * May 1996 * ________________ * * * ISSN 1325-6467 * 1. ABSTRACTS * * Edited by: Craig Savage 2. CONFERENCES * \ | / * Physics, Faculties, ANU, * \__|__/ * 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 * * ___________________ Please send in abstracts for the next newsletter. ___________________ 1. ABSTRACTS ____________ TITLE: Active versus passive squeezing via second harmonic generation AUTHORS: Andrew G. White, Tim C. Ralph, Hans-A. Bachor ADDRESS: Department of Physics, The Faculties, The Australian National University, ACT 0200, AUSTRALIA EMAIL: andrew.white@anu.edu.au JOURNAL: J.O.S.A. B STATUS: Accepted ABSTRACT: The characteristics of squeezed light generated by both passive (occurs in a cavity external to a laser) and active (occurs within a laser cavity) second harmonic generation (SHG) are investigated and contrasted. Squeezing of both the fundamental and the second harmonic is discussed, and the issue of doubly versus singly resonant behaviour is addressed. Passive squeezing is examined by explicitly modelling the intrinsically noisy output of the pump laser and coupling it to a passive, multi-port, lossy SHG cavity. Low frequency degradation of the squeezing due to the laser pump noise is predicted and provides a probable explanation for previous discrepancies between theory and experiment. Active squeezing is quantitatively modelled using a three level laser model that retains all laser dynamics. Previously disparate predictions are reconciled: for one parameter set two regimes of squeezing are predicted, 50% squeezing at frequencies lower than the laser relaxation oscillation, and near perfect squeezing at frequencies above. A particular problem of active squeezing is highlighted: the fast dephasing of the laser coherence introduces considerable excess noise likely to mask squeezing in experimental situations. We conclude that whilst passive SHG is a practical source of squeezing, active SHG is unlikely to be so in the foreseeable future. ____________ TITLE: Experimental test of modular noise propagation theory for quantum optics AUTHORS: Andrew G. White, Matthew S. Taubman, Timothy C. Ralph, Ping Koy Lam, David E. McClelland, and Hans-A. Bachor ADDRESS: Department of Physics, Faculty of Science, The Australian National University, ACT 0200 Australia EMAIL: andrew.white@anu.edu.au JOURNAL: Physical Review A STATUS: Submitted ABSTRACT: We present and test against experiment a general technique that allows modular modelling of noise propagation in quantum optics experiments. Specifically, we consider a multi-element frequency doubling experiment that ultimately produces 1.7 dB/32% (3.0 dB/50% inferred) squeezing at 532 nm. Unlike previous theoretical treatments, we obtain completely analytical expressions for each element of the experiment. This allows intuitive analysis and straightforward experimental modelling. The exact role of driving noise is demonstrated: addition of a narrow linewidth mode cleaning cavity to reduce the driving noise improves the inferred squeezing from 0.75 to 3.0 dB. We find excellent agreement between the modular theory and experiment. ____________ TITLE: Evanescent wave diffraction of multi-level atoms AUTHORS: D. Gordon, C.M. Savage ADDRESS: Department of Physics, Faculty of Science, The Australian National University, ACT 0200 Australia EMAIL: craig.savage@anu.edu.au JOURNAL: Optics Communnications STATUS: In press ABSTRACT: Diffraction of multi-level atoms by an evanescent wave reflective diffraction grating is modeled by numerically solving the time-dependent Schr\"{o}dinger equation. We are able to explain the diffraction observed in experiments with metastable Neon. This is not possible using a two-level atom model. The multi-level model predicts sensitive dependence of diffraction on the laser polarization. For pure p-polarization of the lasers a dark state forms. Associated with this is high order diffraction. http://xxx.lanl.gov/abs/atom-ph/9604004 ____________ TITLE: An atom laser based on Raman transitions AUTHORS: G.M. Moy, J.J. Hope, C.M. Savage ADDRESS: Department of Physics, Faculty of Science, The Australian National University, ACT 0200 Australia EMAIL: craig.savage@anu.edu.au JOURNAL: PRA STATUS: Submitted ABSTRACT: In this paper we present an atom laser scheme using a Raman transition for the output coupling of atoms. A beam of thermal atoms (bosons) in a metastable atomic state |1> are pumped into a multimode atomic cavity. This cavity is coupled through spontaneous emission to a single mode of another cavity for the ground atomic state, |2>. Above a certain threshold pumping rate a large number of atoms, N2, builds up in this single quantum state and transitions to the ground state of the cavity become enhanced by a factor (N2+1). Atoms in this state are then coupled to the outside of the cavity with a Raman transition. This changes the internal state of the atom and imparts a momentum kick, allowing the atoms to leave the system. http://xxx.lanl.gov/abs/atom-ph/9604001 ____________ TITLE: Stimulated Enhancement of Cross-Section by a Bose-Einstein Condensate AUTHORS: J.J. Hope, C.M. Savage ADDRESS: Department of Physics, Faculty of Science, The Australian National University, ACT 0200 Australia EMAIL: craig.savage@anu.edu.au JOURNAL: PRA STATUS: Submitted ABSTRACT: This paper examines the feasibility of constructing an experiment which detects the atomic stimulation of a photon emission process. A beam of atoms (bosons) in an excited state is passed over an atomic trap which traps the atoms when they are in their internal ground state. When the trap contains a Bose-Einstein condensate, the cross-section for absorption of the atomic beam is increased. We examine a particular model in which this atom-stimulation is observable, and is also characterised by the emission of photons in a narrow cone in the direction of the atomic beam. http://xxx.lanl.gov/abs/atom-ph/9602002 &&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&& 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/ &&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&