  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
nonlocal. We show in detail that all the experimental data for these remnant
condensates can be accounted for by minimising a variational energy involving a
nonlocal interatomic potential that is attractive everywhere and that has a
range of the order of the magnetic length.
