Quasiprobability distribution in a Kerr-nonlinear blackbody

In a Kerr-nonlinear blackbody, bare photons with opposite wave vectors and helicities are bound into pairs and unpaired photons are transformed into a new kind of quasiparticle, the nonpolariton. The nonpolariton system constitutes free thermal radiation in the blackbody. In this paper, the quasiprobability (Q function) distribution of thermal radiation is investigated. Non-classical effects of quadrature squeezing have been observed. The structure of nonpolaritons is unsteady and governed by the temperature. The phase space of the photon system is considered and found that in the transition from the normal to the squeezed thermal radiation state, the phase symmetry of the photon system is spontaneously broken.