The exact solution of a fragmented Bose-Hubbard model and twisted models

Abstract

We present the exact solution of a family of fragmented Bose-Hubbard models and represent the models as graphs with the condensates in the vertices. The models are solved by the algebraic Bethe ansatz method. We show that the models have the same spectrum of a family of twisted models that we get by a local U (1) gauge transformation.