Invariance, symmetry and irreversibility in coherence theory

The intrinsic degrees of coherence characterize several properties of partially polarized and partially coherent light. In particular, their properties of invariance by the multiplication of the electric fields by non singular deterministic Jones matrices is reviewed and their ability to exhibit different possible symmetry configurations of the second order statistical properties is discussed. Their evolution when the electric fields of the light are multiplied by random Jones matrices is also analyzed and it is shown that two kinds of irreversible behavior can be exhibited.