Robustness of fragmented condensate many-body states for continuous distribution amplitudes in Fock space

Abstract

We consider a two-mode model describing scalar bosons with two-body interactions in a single trap, taking into account coherent pair-exchange between the modes. It is demonstrated that the resulting fragmented many-body states with continuous (nonsingular) Fock-space distribution amplitudes are robust against perturbations due to occupation number and relative phase fluctuations, Josephson-type tunneling between the modes, and weakly broken parity of orbitals, as well as against perturbations due to interaction with a third mode.