Photonic Superfluidity in a Kerr Nonlinear Black Body

We study a photon blackbody field in Kerr nonlinear crystals in a superfluid state in which 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 photon-pair system is a superfluid and the nonpolariton system is a normal fluid. At zero temperature the superfluid possesses a large persistent energy density. It has been found that the spectral energy density and the radiation pressure of a Kerr nonlinear black body are larger than those of a normal black body.