‘‘Heisenberg microscope’’ decoherence atom interferometry

Atom de Broglie\char21{}wave interference fringes are revealed by their selective destruction. A thermal potassium beam is transmitted through a Talbot-Lau atom interferometer. Different fringe Fourier components resonate in the interferometer at different atomic velocities. The thermal velocity distribution averages and washes out the high-frequency components. ac-modulated laser light passes through the interferometer, is scattered by atoms at one velocity, and destroys, and thereby reveals via the ac modulation, the associated high-frequency fringe contribution.