title: Quantum reflection from a solid surface at normal incidence.
abstract: We observed quantum reflection of ultracold atoms from the attractive potential of a solid surface. Extremely dilute Bose-Einstein condensates of 23Na, with peak density 10(11)-10(12) atoms/cm(3), confined in a weak gravitomagnetic trap were normally incident on a silicon surface. Reflection probabilities of up to 20% were observed for incident velocities of 1-8 mm/s. The velocity dependence agrees qualitatively with the prediction for quantum reflection from the attractive Casimir-Polder potential. Atoms confined in a harmonic trap divided in half by a solid surface exhibited extended lifetime due to quantum reflection from the surface, implying a reflection probability above 50%.
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: Y
authors.initials: Y
authors.lastname: Shin
authors.forename: C
authors.initials: C
authors.lastname: Sanner
authors.forename: M
authors.initials: M
authors.lastname: Saba
authors.forename: A
authors.initials: A
authors.lastname: Schirotzek
authors.forename: D E
authors.initials: DE
authors.lastname: Pritchard
authors.forename: W
authors.initials: W
authors.lastname: Ketterle