Exact solution of a generalized two-sites Bose-Hubbard model
  I introduce a new parametrization of a bosonic Lax operator for the algebraic Bethe ansatz method with the $gl(2)$-invariant $R$-matrix and use it to present the exact solution of a generalized two-sites Bose-Hubbard model with asymmetric tunnelling. In the no interaction limit I show that the Bethe ansatz equations can be written as a $S^{N-1}$ sphere, where $N$ is the total number of atoms in the condensate. 
Gilberto N. Santos Filho
cond-mat.quant-gas hep-th math-ph math.MP nlin.SI quant-ph