Nonlocal energy functionals and long range interactions in collapsing condensates in a box

Abstract

The collapse of attractive Bose–Einstein condensates in a box with tunable interatomic interactions was studied experimentally recently. Not only were remarkably stable remnant condensates observed, but furthermore they often seem to involve two stable plateaus. We suggest that these plateaus correspond in fact to two minima of the energy, the attractive atomic interactions being long-range. We show in detail that all the experimental data for these remnant condensates can be accounted for by minimising a nonlocal variational energy involving a long-range interatomic potential that is attractive everywhere and whose range is of the order of the magnetic length.