Continuous configuration-interaction for condensates in a ring

A continuous configuration-interaction approach for condensates in a ring is introduced. In its simplest form this approach utilizes for attractive condensates the Gross-Pitaevskii symmetry-broken solution and arrives at a ground state of correct symmetry. Furthermore, the energy found is lower than the Gross-Pitaevskii one and, with increasing number of particles and/or strength of inter-particle interaction, is even lower than that accessed by tractable diagonalization of the many-body Hamiltonian. Implications also to excited states are briefly discussed.