Magneto-optical trap loaded from a low-velocity intense source

With a vapor-cell magneto-optical trap (VCMOT) atoms are trapped directly from the equilibrium vapor at room temperature without the complication of a precooling stage. The background vapor, however, can also be a source of energetic atoms hitting and ejecting those atoms already trapped. The background collision limits trap confinement time τ and consequently the total number N of atoms trapped in a VCMOT. In order to have large τ and N without losing the convenience and simplicity of a VCMOT, double MOT systems were built. In such a system there is a VCMOT with a usual background vapor pressure, and connected to it is another MOT without the vapor. The VCMOT captures atoms and transfers them to the second MOT through a long tube. The tube provides the constriction to maintain the pressure difference between the two MOT chambers. For the second MOT there is a steady supply of slow atoms without the complication of the background vapor, and it can hold a large number of atoms for a long time. Such systems were successfully used for a Bose Einstein condensation experiment and to study cold collisions.