ATOM INTERFEROMETERS AND ATOMIC COHERENCE

Atom interferometers are powerful tools for the study of fundamental i ssues in quantum mechanics. This paper describes the use of our atom i nterferometer [1] for an experimental realization of Feynman's gedanke n experiment in which the observation of photons scattered off of part icles emerging from a double slit is used to obtain which path informa tion. This determination, in principal, of the particle's path, destro ys any interference effects downstream. The interference can be regain ed by observing only those particles which scatter a photon into a sma ll range of final directions.