A photon blackbody field in Kerr nonlinear crystal is a squeezed thermal radiation state in which there is a new kind of quasi particle, the nonpolariton. A nonpolariton is a condensate of virtual nonpolar phonons, with a bare photon acting as the nucleus of condensation. The propagation velocity of nonpolaritons is a monotonically increasing function of temperature, and the noise of one quadrature phase in the squeezed thermal radiation state can be below the noise level in the vacuum state. The photon system undergoes a second-order phase transition from the normal to the squeezed thermal radiation state.
© 2002 Optical Society of America
Ze Cheng, "Quantum effects of thermal radiation in a Kerr nonlinear blackbody," J. Opt. Soc. Am. B 19, 1692-1705 (2002)