Fluctuations of a weakly interacting Bose-Einstein condensate

Abstract

Fluctuations of the number of condensed atoms in a finite-size, weakly interacting Bose gas confined in a box potential are investigated for temperatures up to the critical region. The canonical partition functions are evaluated using a recursive scheme for smaller systems, and a saddle-point approximation for larger samples, that allows to treat realistic size systems containing up to $N\sim 10^5$ particles. We point out the importance of particle-number constrain and interactions between out of condensate atoms for the statistics near the critical region. For sufficiently large systems the crossover from the anomalous to normal scaling of the fluctuations is observed. The excitations are described in a self-consistent way within the Bogoliubov-Popov approximation, and the interactions between thermal atoms are described by means of the Hartree-Fock method.

4 pages, 4 figures; vastly improved version, now includes thermal atom interactions for the condensate statistics

References in corpus (5)

• Condensation of classical nonlinear waves
• Direct Observation of Sub-Poissonian Number Statistics in a Degenerate Bose Gas
• Condensation of N interacting bosons: Hybrid approach to condensate fluctuations
• No Anomalous Fluctuations Exist in Stable Equilibrium Systems
• Microcanonical fluctuations of the condensate in weakly interacting Bose gases

Cited by in corpus (6)

• A comparison between microscopic methods for finite temperature Bose gases
• Statistical properties of one dimensional Bose gas
• Thermal effects in light scattering from ultracold bosons in an optical lattice
• Continuum of classical-field ensembles from canonical to grand canonical and the onset of their equivalence
• On the fluctuations of the number of atoms in the condensate
• Bose-Einstein condensation in exotic lattice geometries