  We consider a model of interacting cosmological constant/quintessence, where
dark matter and dark energy behave as, respectively, two coexisting phases of a
fluid, a thermally excited Bose component and a condensate, respectively. In a
simple phenomenological model for the dark components interaction we find that
their energy density evolution is strongly coupled during the universe
evolution. This feature provides a possible way out for the coincidence problem
affecting many quintessence models.
