Self-consistent fragmented excited states of trapped condensates

Abstract

Self-consistent excited states of condensates are solutions of the Gross-Pitaevskii (GP) equation and have been amply discussed in the literature and related to experiments. By introducing a more general mean-field which includes the GP one as a special case, we find a new class of self-consistent excited states. In these states macroscopic numbers of bosons reside in different one-particle functions, i.e., the states are fragmented. Still, a single chemical potential is associated with the condensate. A numerical example is presented, illustrating that the energies of the new, fragmented, states are much lower than those of the GP excited states, and that they are stable to variations of the particle number and shape of the trap potential.