Quantum kinetic theory for evaporative cooling of trapped atoms: Growth ofBose-Einstein condensate

Evaporative cooling of trapped atoms is studied based on the quantum kineti c theory. We extend the classical analysis of Luiten ct al. [Phys. Rev. A 5 3, 381 (1996)] to treat Bose statistics of alkali-metal atoms. Dynamics in evaporative cooling process is described by a kinetic equation for the trun cated Bose-Einstein distribution function under the assumption that the sys tem is close to the thermal equilibrium. This approach is applicable to the "slow" evaporative cooling normally adopted in most experiments for the ef ficient production of Bose-Einstein condensates. Time-evolution calculation s explain the current experiment well with sodium atoms using a slow evapor ative cooling and demonstrate a rapid growth of condensate in the cooling p rocess. [S1050-2947(99)06003-5].