  The aim of this paper is to derive a raw Bloch model for the interaction of
light with quantum boxes in the framework of a two-electron-species (conduction
and valence) description. This requires a good understanding of the one-species
case and of the treatment of level degeneracy. In contrast with some existing
literature we obtain a Liouville equation which induces the positiveness and
the boundedness of solutions, that are necessary for future mathematical
studies involving higher order phenomena.
