Energy and vorticity in fast rotating Bose-Einstein condensates

We study a rapidly rotating Bose-Einstein condensate confined to a finite trap in the framework of two-dimensional Gross-Pitaevskii theory in the strong coupling (Thomas-Fermi) limit. Denoting the coupling parameter by 1/ε2 and the rotational velocity by Ω, we evaluate exactly the next to the leading-order contribution to the ground-state energy in the parameter regime |log ε| ≪ Ω ≪ 1/(ε2|log ε|) with ε → 0. While the TF energy includes only the contribution of the centrifugal forces the next order corresponds to a lattice of vortices whose density is proportional to the rotational velocity. © 2008 IOP Publishing Ltd.