Results of Atom Interferometry Experiments with Potassium

Results of high flux atom interferometry experiments with potassium in generalized Talbot-Lou configurations are presented. The interferometer consists of a sequence of three planar vacuum-slit diffraction gratings, microfabricated from silicon nitride membranes. Interference fringes are sensed by measuring the transmission of atoms on a hot-wire as a function of grating relative position. Different spatial Fourier components in the diffraction pattern are resonant in the interferometer at different atomic velocities. When a laser cooled slow beam is incident, various different diffraction patterns are observed as a function of atomic velocity, selected via the tuning of cooling lasers. In an alternative “Heisenberg Microscope” configuration an incident thermal beam produces a velocity average over different fringe patterns that averages over and washes out the high frequency Fourier components. In this configuration AC modulated laser light passes through the interferometer. Via the Doppler shift, it is scattered only by atoms in a narrow velocity band. Since imaging of the fluorescent light could determine which slit an atom passes, the laser destroys, and thereby reveals via the AC modulation, the associated high-frequency fringe contribution.