Quadrupole oscillation of a single-vortex Bose-Einstein condensate: evidence for Kelvin modes.
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.
Bretin
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V
Laboratoire Kastler Brossel, 24 rue Lhomond, 75005 Paris, France.
Rosenbusch
P
P
Chevy
F
F
Shlyapnikov
G V
GV
Dalibard
J
J