arXiv:cond-mat/0212290 · Journal of Physics B Atomic Molecular and Optical Physics
Gyroscopic motion of superfluid-trapped atomic condensates
Halvor M ll Nilsen, Dermot McPeake, J F McCann
Abstract
The gyroscopic motion of a trapped Bose gas containing a vortex is studied. We model the system as a classical top, as a superposition of coherent hydrodynamic states, by solution of the Bogoliubov equations, and by integration of the time-dependent Gross–Pitaevskii equation. The frequency spectrum of Bogoliubov excitations, including quantum frequency shifts, is calculated and the quantal precession frequency is found to be consistent with experimental results, although a small discrepancy does exist. The superfluid precession is found to be well described by the classical and hydrodynamic models. However, the frequency shifts and helical oscillations associated with vortex bending and twisting require a quantal treatment. In gyroscopic precession, the Kelvin modes m = ±1 are the dominant features giving a vortex kink or bend, while the m = +2 mode is found to be the dominant Kelvin wave associated with vortex twisting.