title: Quadrupole oscillation of a single-vortex Bose-Einstein condensate: evidence for Kelvin modes.
abstract: We study the two transverse quadrupole modes of a cigar-shaped Bose-Einstein condensate with a single centered vortex. We show that the counterrotating mode is more strongly damped than in the absence of a vortex, whereas the corotating mode is not affected appreciably by the vortex. We interpret this result as a decay of the counterrotating quadrupole mode into two excitations of the vortex line, the so-called Kelvin modes. This is supported by direct observation of the vortex line.
authors.affiliation: Laboratoire Kastler Brossel, 24 rue Lhomond, 75005 Paris, France.
authors.forename: V
authors.initials: V
authors.lastname: Bretin
authors.forename: P
authors.initials: P
authors.lastname: Rosenbusch
authors.forename: F
authors.initials: F
authors.lastname: Chevy
authors.forename: G V
authors.initials: GV
authors.lastname: Shlyapnikov
authors.forename: J
authors.initials: J
authors.lastname: Dalibard