Abstract

Results of high-flux atom-interferometry experiments with potassium in generalized Talbot-vonLau configurations² 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 (up to sixth) 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 atom cooling lasers^3. In an alternative "Heisenberg Microscope" configuration⁴ an incident thermal beam produces a velocity average over different fringe Fourier components. Fringe patterns for each HFS component are revealed by their selective destruction by AC modulated weak laser light passing through the interferometer near the middle grating. Since imaging of the fluorescent light could determine which slit an atom passes, the laser removes the fringe pattern contribution by Doppler shifted atoms at its wavelength. That contribution is then AC modulated and detected. While the 39_K hyperfine structure is not resolved in the fluorescence spectrum, by contrast, the transmission spectrum of the interferometer (as a function of laser tuning) displays two well-resolved peaks whose the spacing corresponds to the ground-state hyperfine structure. The interferometer thus acts as an atom interference filter, whose velocity selectivity allows us to narrow the effective transmitted velocity range, and improve the optical spectral resolution.

© 1994 Optical Society of America