The Two-Dimensional Bose-Einstein Condensate
نویسندگان
چکیده
We study the Hartree-Fock-Bogoliubov mean-field theory as applied to a two-dimensional finite trapped Bose gas at low temperatures and find that, in the Hartree-Fock approximation, the system can be described either with or without the presence of a condensate; this is true in the thermodynamic limit as well. We are unable to find condensate solutions when we consider a scheme that predicts the presence of phonons; moreover, the uncondensed solution, which is still valid when phonons are allowed, has a lower free energy at all temperatures. This seems to indicate that low-energy phonons destabilize the two-dimensional condensate.
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