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dc.contributor.authorWiseman, Howarden_US
dc.contributor.authorA. Vaccaro, Johnen_US
dc.date.accessioned2017-05-03T11:50:57Z
dc.date.available2017-05-03T11:50:57Z
dc.date.issued2002en_US
dc.date.modified2009-09-03T07:13:45Z
dc.identifier.issn10502947en_US
dc.identifier.doi10.1103/PhysRevA.65.043605en_AU
dc.identifier.urihttp://hdl.handle.net/10072/6959
dc.description.abstractA laser, be it an optical laser or an atom laser, is an open quantum system that produces a coherent beam of bosons (photons or atoms, respectively). Far above threshold, the stationary state ?ss of the laser mode is a mixture of coherent-field states with random phase, or, equivalently, a Poissonian mixture of number states. This paper answers the question: can descriptions such as these, of ?ss as a stationary ensemble of pure states, be physically realized? Here physical realization is as defined previously by us [H. M. Wiseman and J. A. Vaccaro, Phys. Lett. A 250, 241 (1998)]: an ensemble of pure states for a particular system can be physically realized if, without changing the dynamics of the system, an experimenter can (in principle) know at any time that the system is in one of the pure-state members of the ensemble. Such knowledge can be obtained by monitoring the baths to which the system is coupled, provided that coupling is describable by a Markovian master equation. Using a family of master equations for the (atom) laser, we solve for the physically realizable (PR) ensembles. We find that for any finite self-energy ? of the bosons in the laser mode, the coherent-state ensemble is not PR; the closest one can come to it is an ensemble of squeezed states. This is particularly relevant for atom lasers, where the self-energy arising from elastic collisions is expected to be large. By contrast, the number-state ensemble is always PR. As the self-energy ? increases, the states in the PR ensemble closest to the coherent-state ensemble become increasingly squeezed. Nevertheless, there are values of ? for which states with well-defined coherent amplitudes are PR, even though the atom laser is not coherent (in the sense of having a Bose-degenerate output). We discuss the physical significance of this anomaly in terms of conditional coherence (and hence conditional Bose degeneracy).en_US
dc.description.peerreviewedYesen_US
dc.description.publicationstatusYesen_AU
dc.format.extent471281 bytes
dc.format.mimetypeapplication/pdf
dc.languageEnglishen_US
dc.language.isoen_AU
dc.publisherAmerican Physical Societyen_US
dc.publisher.placeUSAen_US
dc.publisher.urihttp://pra.aps.org/en_AU
dc.relation.ispartofpagefrom043605.1en_US
dc.relation.ispartofpageto043605.19en_US
dc.relation.ispartofjournalPhysical Review A: Atomic, Molecular and Optical Physicsen_US
dc.relation.ispartofvolume65en_US
dc.subject.fieldofresearchcode240201en_US
dc.titleAtom lasers, coherent states, and coherence: I. Physically realizable ensembles of pure statesen_US
dc.typeJournal articleen_US
dc.type.descriptionC1 - Peer Reviewed (HERDC)en_US
dc.type.codeC - Journal Articlesen_US
gro.rights.copyrightCopyright 2002 American Physical Society. This is the author-manuscript version of this paper. Reproduced in accordance with the copyright policy of the publisher. Please refer to the journal link for access to the definitive, published version.en_AU
gro.date.issued2002
gro.hasfulltextFull Text


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