Multiplex velocity selection for precision matter-wave interferometry

We describe a novel velocity-selection technique for measuring dispersive phase shifts in matter-wave interferometers. Where conventional velocity-selection techniques simply reduce the width of the initial velocity distribution, here, the velocity distribution is chopped into a series of narrow peaks such that the velocity dependence of the phase shifts will result in a rephasing of the interference for certain strengths of applied potential. This technique overcomes limitations due to wide and poorly known velocity distributions and thus allows a better determination of the applied interaction with complete independence from the initial velocity distribution of the beam.Dedicated to H. Walther on the occasion of his 60th birthday