Collective excitations of a 87 Rb Bose condensate in the Thomas-Fermi regime

Abstract
Collective excitations have been observed in a 87Rb Bose condensate, confined in a magneto-static, elongated, harmonic trap. We have measured the frequency of two different modes with zero angular momentum along the symmetry axis of the trap. Both the frequencies are in good agreement with the values predicted by the hydrodynamic theory of superfluids holding in the Thomas-Fermi regime.