We observe the build-up of a matter wave interference pattern from single atom detection events in a double-slit experiment. The interference arises from two overlapping atom laser beams extracted from a Rubidium Bose-Einstein condensate. Our detector is a high-finesse optical cavity which realizes the quantum measurement of the presence of an atom and thereby projects delocalized atoms into a state with zero or one atom in the resonator. The experiment reveals simultaneously the granular and the wave nature of matter.
@article{arxiv.cond-mat/0511234,
title = {Cavity QED Detection of Interfering Matter Waves},
author = {T. Bourdel and T. Donner and S. Ritter and A. Öttl and M. Köhl and T. Esslinger},
journal= {arXiv preprint arXiv:cond-mat/0511234},
year = {2009}
}