Fragmentation of Bose-Einstein Condensates
  We present the theory of bosonic systems with multiple condensates, unifying disparate models which are found in the literature, and discuss how degeneracies, interactions, and symmetries conspire to give rise to this unusual behavior. We show that as degeneracies multiply, so do the types of fragmentation, eventually leading to strongly correlated states with no trace of condensation. 
Erich J. Mueller (Cornell), Tin-Lun Ho (OSU), Masahito Ueda (Tokyo   Institute of Technology) and Gordon Baym (UIUC)