The Two-Dimensional Bose-Einstein Condensate
Abstract
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. Of the two solutions, the one that includes a condensate has a lower free energy at all temperatures. However, the Hartree-Fock scheme neglects the presence of phonons within the system, and when we allow for the possibility of phonons we are unable to find condensed solutions; the uncondensed solutions, on the other hand, are valid also in the latter, more general scheme. Our results confirm that low-energy phonons destabilize the two-dimensional condensate.
- Publication:
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arXiv e-prints
- Pub Date:
- March 2002
- DOI:
- 10.48550/arXiv.cond-mat/0203175
- arXiv:
- arXiv:cond-mat/0203175
- Bibcode:
- 2002cond.mat..3175F
- Keywords:
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- Condensed Matter - Statistical Mechanics
- E-Print:
- 8 pages, 3 figures, REVTeX 4. To appear in J. Low Temp. Phys. Corrected a mistake in a calculation and changed the conclusions accordingly