Longitudinal atom interferometry

A detuned, radiofrequency field interacting with atoms in an atomic beam co nstitutes a beamsplitter in longitudinal momentum space. Using such beamspl itters, we have constructed a longitudinal atom interferometer in a general ization of Ramsey's classic SOF configuration. This interferometer is well- suited to studying the longitudinal coherence properties of matter-wave bea ms. We report on two such experiments, including a deconvolution of the lon gitudinal density matrix of an atomic beam and a search for longitudinal co herences coming from our supersonic beam source.