TIME-DEPENDENT CONTROL OF ULTRACOLD ATOMS IN MAGNETIC TRAPS

With radio-frequency fields one can control ultracold atoms in magneti c traps. These fields couple the atomic spin states, and are used in e vaporative cooling that can lead to Bose-Einstein condensation in the atom cloud. Also, they can be used in controlled release of the conden sate from the trap, thus providing output couplers for atom lasers. In this paper we show that the time-dependent multistate models for thes e processes have exact solutions that are polynomials of the solutions of the corresponding two-state models. This allows simple, in many ca ses analytic, descriptions for the time-dependent control of the magne tically trapped ultra-cold atoms. [S1050-2947(97)50712-8].