Quantum kinetic theory. IV. Intensity and amplitude fluctuations of a BoseEinstein condensate at finite temperature including trap loss
Abstract
We use the quantum kinetic theory to calculate the steady state and fluctuations of a trapped BoseEinstein condensate at a finite temperature. The system is divided in a condensate and a noncondensate part. A quantummechanical description based on the numberconserving Bogoliubov method is used for describing the condensate part. The noncondensed particles are treated as a classical gas in thermal equilibrium with temperature T and chemical potential μ. We find a master equation for the reduced density operator of the BoseEinstein condensate, calculate the steady state of the system, and investigate the effect of one, two, and threeparticle losses on the condensate. Using linearized Ito equations, we find expressions for the intensity fluctuations and the amplitude fluctuations in the condensate. A Lorentzian line shape is found for the intensity correlation function that is characterized by a time constant γ^{1}_{I} derived in the paper. For the amplitude correlation function, we find ballistic behavior for time differences smaller than γ^{1}_{I}, and diffusive behavior for larger time differences.
 Publication:

Physical Review A
 Pub Date:
 August 1998
 DOI:
 10.1103/PhysRevA.58.1450
 arXiv:
 arXiv:condmat/9712206
 Bibcode:
 1998PhRvA..58.1450J
 Keywords:

 03.75.Fi;
 74.40.+k;
 42.50.Lc;
 Fluctuations;
 Quantum fluctuations quantum noise and quantum jumps;
 Condensed Matter  Statistical Mechanics
 EPrint:
 15 pages with 7 figures to appear in Phys. Rev. A