INTERFEROMETRIC MEASUREMENT OF AN ATOMIC WAVE-FUNCTION

We discuss a simple method to probe the wave function psi(x) describin g the transverse center-of-mass motion of an atomic beam. We detect po sition distributions of the atoms after they have interacted with two counterpropagating laser beams. The resulting interference pattern dep ends crucially on the cross term psi(x)psi(x - Delta x), which finall y allows us to reconstruct the phase of psi(x).