SEMICLASSICAL ANALYSIS OF COLLECTIVE EXCITATIONS IN BOSE-EINSTEIN CONDENSATE

We investigate the low-lying excitations of Bose-Einstein condensate o f confined alkali-metal atoms, with repulsive interaction. Vortex exci tation energy of the condensate a large number of atoms is estimated s emiclassically. We also investigate the asymptotic form of the low-ene rgy quasiparticle excitation of the condensate in the presence of a vo rtex, in the large-N Limit. The dispersion relation remains the same a s that of a condensate without a vortex, except the z component of ang ular momentum of the modes is shifted by the angular momentum of the v ortex. The first-order correction of the energy eigenvalues due to fin ite-size effects is calculated.