title: Observation of the scissors mode and evidence for superfluidity of a trapped bose-einstein condensed Gas
abstract: We report the observation of the scissors mode of a Bose-Einstein condensed gas of 87Rb atoms in a magnetic trap, which gives direct evidence of superfluidity in this system. The scissors mode of oscillation is excited by a sudden rotation of the anisotropic trapping potential. For a gas above T(c) (normal fluid) we detect the occurrence of oscillations at two frequencies, with the lower frequency corresponding to the rigid body value of the moment of inertia. Well below T(c) the condensate oscillates at a single frequency, without damping, as expected for a superfluid.
authors.affiliation: Clarendon Laboratory, Department of Physics, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom.
authors.initials: OM
authors.lastname: Marago
authors.initials: SA
authors.lastname: Hopkins
authors.initials: J
authors.lastname: Arlt
authors.initials: E
authors.lastname: Hodby
authors.initials: G
authors.lastname: Hechenblaikner
authors.initials: CJ
authors.lastname: Foot