Green's function method to the ground state properties of a two-component Bose-Einstein condensate
Chen Liang, Kong Wei, B.J. Ye, H.M. Wen, X.Y. Zhou, and R.D. Han
Department of Modern Physics, University of Science and Technology of China, Hefei 230026, China
Received November 25, 2010
The elementary excitation spectrum of a two-component Bose–Einstein condensate is obtained by Green’s
function method. It is found to have two branches. In the long-wave limit, the two branches of the excitation spectrum are reduced to one phonon excitation and one single-particle excitation. With the obtained excitation spectrum and the Green’s functions, the depletion of the condensate and the ground state energy have also been calculated in this paper.
PACS: 03.75.Nt Other Bose–Einstein condensation phenomena.