ATOMIC PHASE-CONJUGATION FROM A BOSE CONDENSATE

We discuss the possibility of observing atomic phase conjugation from Bose condensates, and using it as a diagnostic tool to access the spat ial coherence properties and to measure the lifetime of the condensate . We argue that since phase conjugation results from the scattering of a partial matter wave off the spatial grating produced by two other w aves, it offers a natural way to directly measure such properties, and as such provides an attractive alternative to the optical methods pro posed in the past.