title: Observation of atom pairs in spontaneous four-wave mixing of two colliding Bose-Einstein condensates.
abstract: We study atom scattering from two colliding Bose-Einstein condensates using a position sensitive, time resolved, single atom detector. In analogy to quantum optics, the process can also be thought of as spontaneous, degenerate four-wave mixing of de Broglie waves. We find a clear correlation between atoms with opposite momenta, demonstrating pair production in the scattering process. We also observe a Hanbury Brown-Twiss correlation for collinear momenta, which permits an independent measurement of the size of the pair production source and thus the size of the spatial mode. The back-to-back pairs occupy very nearly two oppositely directed spatial modes, a promising feature for future quantum optics experiments.
authors.affiliation: Laboratoire Charles Fabry de l'Institut d'Optique, CNRS, Univ Paris-Sud, Campus Polytechnique, RD128, 91127 Palaiseau cedex, France.
authors.forename: A
authors.initials: A
authors.lastname: Perrin
authors.forename: H
authors.initials: H
authors.lastname: Chang
authors.forename: V
authors.initials: V
authors.lastname: Krachmalnicoff
authors.forename: M
authors.initials: M
authors.lastname: Schellekens
authors.forename: D
authors.initials: D
authors.lastname: Boiron
authors.forename: A
authors.initials: A
authors.lastname: Aspect
authors.forename: C I
authors.initials: CI
authors.lastname: Westbrook