Waves on an interface between two phase-separated Bose-Einstein condensates

Since a study of excited states of an immiscible system was lacking, normal modes for intercomponent boundary oscillations in the weakly segregated phase regime was considered. The Bogoliubov spectrum of a translationally invariant mixed BEC was obtained, but it revealed only the fact that such a homogeneous system was dynamically unstable against long-wavelength perturbations. Hence, tends to become phase separated.