  The causal interpretation of quantum mechanics is applied to a homogeneous
and isotropic quantum universe, whose matter content is composed by non
interacting dust and radiation. For wave functions which are eigenstates of the
total dust mass operator, we find some bouncing quantum universes which reachs
the classical limit for scale factors much larger than its minimum size.
However these wave functions do not have unitary evolution. For wave functions
which are not eigenstates of the dust total mass operator but do have unitary
evolution, we show that, for flat spatial sections, matter can be created as a
quantum effect in such a way that the universe can undergo a transition from an
exotic matter dominated era to a matter dominated one.
