Hannover 2003 – scientific programme

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Q: Quantenoptik

Q 35: Quantengase 3: Gruppenberichte

Q 35.2: Group Report

Thursday, March 27, 2003, 11:30–12:00, E001

Dynamics of a Single Vortex Line in a Bose-Einstein Condensate — •Peter Rosenbusch, Vincent Bretin, Fréderic Chevy, and Jean Dalibard — Laboratoire Kaster Brossel, 24 rue Lhomond, 75231 Paris, FRANCE

We study experimentally the line of a single vortex in a rotating prolate Bose-Einstein condensate (BEC) confined by a harmonic potential [1]. In agreement with predictions, we find that the vortex line is in most cases curved at the ends. We monitor its time evolution from the state where the angular momentum per particle is ℏ to the vortex-free condensate. The length of the vortex line is measured as a function of time and temperature. For a low temperature, the survival time can be as large as 10 seconds, decreasing with increasing temperature.

We also present evidence for oscillations of the single centered vortex line, the so called Kelvin modes [2]. The difference in the decay rates of the two transverse quadrupole modes m=±2 is attributed to a Beliaev-type excitation of the Kelvin modes, only possible for m=−2. This is supported by direct imaging of the wiggling vortex line.

[1] P. Rosenbusch, V. Bretin, and J. Dalibard, Phys. Rev. Lett. 89 200403 (2002)

[2] V. Bretin, P. Rosenbusch, F. Chevy, G. Shlyapnikov, and J. Dalibard, cond-mat/0211101