Conserving Gapless Mean-Field Theory of a Multi-Component Bose-Einstein Condensate

Abstract

We develop a mean-field theory for Bose-Einstein condensation of spin-1 atoms with internal degrees of freedom. It is applicable to nonuniform systems at finite temperatures with a plausible feature of satisfying the Hugenholtz-Pines theorem and various conservation laws simultaneously. Using it, we clarify thermodynamic properties and the excitation spectra of a uniform gas. The condensate is confirmed to remain in the same internal state from T=0 up to $T_c$ for both antiferromagnetic and ferromagnetic interactions. The excitation spectra of the antiferromagnetic (ferromagnetic) interaction are found to have only a single gapless mode, contrary to the prediction of the Bogoliubov theory where three (two) of them are gapless. We present a detailed discussion on those single-particle excitations in connection with the collective excitations.

8 pages, 7 figures Minor errors removed

References in corpus (3)

• Dynamics of F=1 87Rb condensates at finite temperatures
• Bose-Einstein condensation of trapped interacting spin-1 atoms
• Conserving Gapless Mean-Field Theory for Weakly Interacting Bose Gases

Cited by in corpus (1)

• Vortex splitting and phase separating instabilities of coreless vortices in F=1 spinor Bose-Einstein condensates