title: Low velocity quantum reflection of Bose-Einstein condensates.
abstract: We study how interactions affect the quantum reflection of Bose-Einstein condensates. A patterned silicon surface with a square array of pillars resulted in high reflection probabilities. For incident velocities greater than 2.5 mm/s, our observations agreed with single-particle theory. At velocities below 2.5 mm/s, the measured reflection probability saturated near 60% rather than increasing towards unity as predicted by the accepted theoretical model. We extend the theory of quantum reflection to account for the mean-field interactions of a condensate which suppresses quantum reflection at low velocity. The reflected condensates show collective excitations as recently predicted.
authors.affiliation: Department of Physics, MIT-Harvard Center for Ultracold Atoms, and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.forename: T A
authors.initials: TA
authors.lastname: Pasquini
authors.forename: M
authors.initials: M
authors.lastname: Saba
authors.forename: G-B
authors.initials: GB
authors.lastname: Jo
authors.forename: Y
authors.initials: Y
authors.lastname: Shin
authors.forename: W
authors.initials: W
authors.lastname: Ketterle
authors.forename: D E
authors.initials: DE
authors.lastname: Pritchard
authors.forename: T A
authors.initials: TA
authors.lastname: Savas
authors.forename: N
authors.initials: N
authors.lastname: Mulders