Electromagnetic field state description with correlation functions of different nature

Modern electromagnetic theory based on quantum conceptions supposes turn to averages of operator dynamic variables for describing the field state and analyzing experimental results with computational methods. Theoretical analysis of such non-equilibrium phenomenon as Dicke superfluorescence leads to an algebra of variables which are necessary for building a set of evolution equations. Rather different correlation functions can be determined in measurements according to the coincidence scheme using Glauber's quantum detectors. A natural way of connecting various correlation functions is expressing them via the photon density matrix and Wigner function. The problem of comparing the theoretical and experimental approaches is analyzed in the present paper.