Beliaev damping and Kelvin mode spectroscopy of a Bose-Einstein condensate in the presence of a vortex line.
It is demonstrated theoretically that the counter-rotating quadrupole mode in a vortex of Bose-Einstein condensates can decay into a pair of Kelvin modes via the Beliaev process. We calculate the spectral weight of a density-response function within the Bogoliubov framework, taking account of both Beliaev and Landau processes. Good agreement with experiment on 87 Rb by Bretin et al. [Phys. Rev. Lett., 100403 (2003)]] allows us to unambiguously identify the decayed mode as the Kelvin wave propagating along a vortex line.
Mizushima
T
T
Department of Physics, Okayama University, Okayama 700-8530, Japan.
Ichioka
M
M
Machida
K
K