Polarization properties of multiphoton processes in quantum systems with large angular momentum

We generalize an approach (previously proposed by two of the authors) to de scribe quantum systems with large angular momentum exposed to a radiation f ield. The approach exploits a transformation from the quantum-mechanical de scription to the classical one with respect to angular momentum orientation . The transformation is carried out through a density matrix representation similar to the well known Wigner representation for the translational degr ees of freedom. The generalization opens up the possibility of describing t he interaction of polychromatic radiation (i.e. a set of monochromatic comp onents) with a quantum system when the spectral components of the radiation are resonant to different transitions of the system. It follows naturally from the obtained equations that if the solution of the problem within the framework of the model of nondegenerate states is known, then its generaliz ation for the case of state degeneracy and accounting for polarization of i nteracting fields is given by the simplest operation. As an example, the pr oposed method is applied to stimulated Raman scattering and four-wave mixin g. We pay special attention to those polarization features which, on the on e hand, are interesting to experimentalists and, on the other hand, have no t yet been given an adequate explanation in the literature.