Nonequilibrium Evolution Of A Trapped Bose Gas

V. E. Colussi, Cameron Straatsma, Dana Z. Anderson +1 more

Tarun Kanti Ghosh

Makoto Yamashita, Masato Koashi, N. Imoto

Summary form only given.The successful demonstrations of Bose-Einstein condensation (BEG) with alkali atoms in a magnetic trap have opened up a new field of quantum physics. The evaporative cooling that enables six-order increase of phase space density is the essential technique for achieving the BEC transition in these experiments. However, at low temperatures, this cooling method is strongly affected by Bose statistics of alkali atoms, since evaporation occurs through the scattering process between trapped atoms. The quantum kinetics of nonequilibrium gas has been the subject of considerable interest for classic gas on the basis of truncated Boltzman distribution. We extend this method to treat the quantum statistics.

Michiel J. Bijlsma, Henk T. C. Stoof

Renu Bala, K. N. Pathak

J. Wachter, R. Walser, J. Cooper +1 more

We discuss the equivalence of two nonequilibrium kinetic theories that describe the evolution of a dilute, Bose-Einstein condensed atomic gas in a harmonic trap. The second-order kinetic equations of Walser et al. [Phys. Rev. A 63, 013607 (2001)] reduce to the Gross-Pitaevskii equation and the quantum Boltzmann equation in the low- and high-temperature limits, respectively. These kinetic equations thus describe the system in equilibrium (finite temperature) as well as in nonequilibrium (real time). We have found this theory to be equivalent to the nonequilibrium Green's function approach originally proposed by Kadanoff and Baym and more recently applied to inhomogeneous trapped systems by Imamovi\ifmmode \acute{c}\else \'{c}\fi{}-Tomasovi\ifmmode \acute{c}\else \'{c}\fi{} and Griffin [in Progress in Nonequilibrium Green's Functions, edited by M. Bonitz (World Scientific, Singapore, 2000), p. 404].