2001/04/30 by Tarun Kanti Ghosh
Physics and Astronomy · #cond-mat
published as Physical Review A 65, 053616 (2002). · 9 pages, 4 figures, version to appear in Physical Review A
arxiv created 2002/04/01 · arxiv updated 2009/11/30
We study the collective excitations of a neutral atomic Bose-Einstein condensate with gravity-like 1/r interatomic attraction induced by electromagnetic wave. Using the time-dependent variational approach, we derive an analytical spectrum for monopole and quadrupole mode frequencies of a gravity-like self-bound Bose condensed state at zero temperature. We also analyze the excitation frequencies of the Thomas-Fermi-gravity (TF-G) and gravity (G) regimes. Our result agrees excellently with that of Giovanazzi \em et al. [Europhysics Letters, \bf 56, 1 (2001)], which is obtained within the sum-rule approach. We also consider the vortex state. We estimate the superfluid coherence length and the critical angular frequencies to create a vortex around the z -axis. We find that the TF-G regime can exhibit the superfluid properties more prominently than the G-regime. We find that the monopole mode frequency of the condensate decreases due to the presence of a vortex.