title: Symmetry breaking and enhanced condensate fraction in a matter-wave bright soliton.
abstract: An exact diagonalization study reveals that a matter-wave bright soliton and the Goldstone mode are simultaneously created in a quasi-one-dimensional attractive Bose-Einstein condensate by superpositions of quasidegenerate low-lying many-body states. Upon formation of the soliton the maximum eigenvalue of the single-particle density matrix increases dramatically, indicating that a fragmented condensate converts into a single condensate as a consequence of the breaking of translation symmetry.
authors.affiliation: Department of Physics, Osaka City University, Osaka 558-8585, Japan.
authors.forename: Rina
authors.initials: R
authors.lastname: Kanamoto
authors.forename: Hiroki
authors.initials: H
authors.lastname: Saito
authors.forename: Masahito
authors.initials: M
authors.lastname: Ueda