Solitary-wave solutions in binary mixtures of Bose-Einstein condensates   under periodic boundary conditions
  We derive solitary-wave solutions within the mean-field approximation in quasi-one-dimensional binary mixtures of Bose-Einstein condensates under periodic boundary conditions, for the case of an effective repulsive interatomic interaction. The particular gray-bright solutions that give the global energy minima are determined. Their characteristics and the associated dispersion relation are derived. In the case of weak coupling, we diagonalize the Hamiltonian analytically to obtain the full excitation spectrum of "quantum" solitary-wave solutions. 
J. Smyrnakis, M. Magiropoulos, G. M. Kavoulakis, A. D. Jackson
cond-mat.quant-gas math-ph math.MP