Localized oscillating fields are beam splitters that can entangle internal and longitudinal momentum states in an atomic beam. Differentially detuned separated oscillatory fields and an am modulator constitute a “white fringe” longitudinal interferometer which rephases velocity averaging by a process analogous to half a spin echo. Differentially detuned separated oscillatory fields are used to produce a downstream coherence or rephase an upstream coherence in an atomic beam.

• Received 18 March 1998

DOI:https://doi.org/10.1103/PhysRevLett.81.1996