Sunday, May 19, 2013

1305.3878 (J. C. Cremon et al.)

Vortices in Bose-Einstein condensates - finite-size effects and the
thermodynamic limit

J. C. Cremon, G. M. Kavoulakis, B. R. Mottelson, S. M. Reimann
For a weakly-interacting Bose gas rotating in a harmonic trap we relate the yrast states of small systems (that can be treated exactly) to the thermodynamic limit (derived within the mean-field approximation). For a few dozens of atoms, the yrast line shows distinct quasi-periodic oscillations with increasing angular momentum that originate from the internal structure of the exact many-body states. These finite-size effects disappear in the thermodynamic limit, where the Gross-Pitaevskii approximation provides the exact energy to leading order in the number of particles N. However, the exact yrast states reveal significant structure not captured by the mean-field approximation: Even in the limit of large N, the corresponding mean-field solution accounts for only a fraction of the total weight of the exact quantum state.
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