Miscibility transition in a binary Bose-Einstein condensate induced by linear interconversion

We consider a model of a two-component condensate in one dimension, where the components represent two different spin states of the same atom. We demonstrate that linear interconversion between them, induced by a resonant electromagnetic wave, can make the immiscible binary condensate miscible. This transition is predicted by means of a variational approximation, and is then confirmed by direct numerical solutions of the symmetric and asymmetric models (the asymmetry is accounted for by a chemical-potentil difference between the components). The dependence of the corresponding order parameters on the linear-coupling strengths reveals a typical phase transition of the second kind. However, in dynamic states the species may remain separated, even if they would get mixed in a static configuration.