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VERSION:2.0
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PRODID:UW-Madison-Physics-Events
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SEQUENCE:0
UID:UW-Physics-Event-3091
DTSTART:20130926T150000Z
DURATION:PT1H0M0S
DTSTAMP:20260419T212208Z
LAST-MODIFIED:20130920T144751Z
LOCATION:Chamberlin 5310
SUMMARY:Cavity-mediated near-critical dissipative dynamics of a driven
  condensate\, R. G. Herb Condensed Matter Seminar\, Dr. Manas Kulkarni
 \, Princeton University
DESCRIPTION:We investigate the near-critical dynamics of atomic densit
 y fluctuations in the non-equilibrium self-organization transition of 
 an optically driven quantum gas coupled to a single mode of a cavity. 
 In this system cavity-mediated long-range interactions between atoms\,
  tunable by the drive strength\, lead to softening of an excitation mo
 de recently observed in experiments. This phenomenon has previously be
 en studied within a two-mode approximation for the collective motional
  degrees of freedom of the atomic condensate which results in an effec
 tive open-system Dicke model. Here\, including the full spectrum of at
 omic modes we find a finite lifetime for a roton-like mode in the Bogo
 liubov excitation spectrum that is strongly pump-dependent. The corres
 ponding decay rate and critical exponents for the phase-transition are
  calculated explaining the non-monotonic pump-dependent atomic damping
  rate observed in recent experiments. We compute the near-critical beh
 avior of the intra-cavity field fluctuations\, that has been previousl
 y shown to be enhanced with respect to the equilibrium Dicke model in 
 a two-mode approximation. We highlight the role of the finite size of 
 the system in the suppression of it below the expectations of the open
  Dicke model.
URL:https://www.physics.wisc.edu/events/?id=3091
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