Analysis of the bichromatic atomic beam splitter

Abstract

We compare the properties of the bichromatic atomic beam splitter where the light field is treated classically and quantum mechanically. This beam splitter has been proposed as a configuration which produces two cleanly-separated diffracted beams. It is found that for a classical field with a definite temporal phase relationship between the standing waves, an incoming atomic beam is in general split unequally between the two orders, the ratio of the outgoing beams being dependent on the atomic state and on the phase relationship at the time at which the atom enters the field. In previous analyses of this beam splitter, the light fields have been assumed to be in number states leading to a symmetrical splitting of the atomic beam. The relative insensitivity of the bichromatic beam-splitter to the failure of the Raman-Nath approximation predicted by Grimm et al. is confirmed for a rectangular optical profile, but the results for a Gaussian profile suggest that operation in the Raman-Nath regime is still required for clean beam-splitting.