Quantum kinetic theory. IV. Intensity and amplitude fluctuations of a Bose-Einstein condensate at finite temperature including trap loss
Abstract
We use the quantum kinetic theory to calculate the steady state and fluctuations of a trapped Bose-Einstein condensate at a finite temperature. The system is divided in a condensate and a noncondensate part. A quantum-mechanical description based on the number-conserving 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 Bose-Einstein condensate, calculate the steady state of the system, and investigate the effect of one-, two-, and three-particle 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-1I derived in the paper. For the amplitude correlation function, we find ballistic behavior for time differences smaller than γ-1I, and diffusive behavior for larger time differences.
- Publication:
-
Physical Review A
- Pub Date:
- August 1998
- DOI:
- 10.1103/PhysRevA.58.1450
- arXiv:
- arXiv:cond-mat/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
- E-Print:
- 15 pages with 7 figures to appear in Phys. Rev. A