title: Observation of superfluid flow in a bose-einstein condensed Gas
abstract: We have studied the hydrodynamic flow in a Bose-Einstein condensate stirred by a macroscopic object, a blue-detuned laser beam, using nondestructive in situ phase contrast imaging. A critical velocity for the onset of a pressure gradient has been observed, and shown to be density dependent. The technique has been compared to a calorimetric method used previously to measure the heating induced by the motion of the laser beam.
authors.affiliation: Department of Physics and Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
authors.initials: R
authors.lastname: Onofrio
authors.initials: C
authors.lastname: Raman
authors.initials: JM
authors.lastname: Vogels
authors.initials: JR
authors.lastname: Abo-Shaeer
authors.initials: AP
authors.lastname: Chikkatur
authors.initials: W
authors.lastname: Ketterle