Analysis of nonclassical behavior for a two-mode coupled-photon system

We consider a model two-mode coupled-photon system and verify that the photon distribution for this system is exactly super-Poissonian. We calculate the Glauber-Sudarshan diagonal P representation for both the individual photon subsystem and the complete photon-photon complex. We present the detailed analysis on the threshold temperature of the nonclassical behavior for the both cases. We discuss the effect of the interaction between two photons on the threshold temperature.