Characteristics of four-wave mixing in a Bose-condensed atomic gas

An analysis is made of four-wave mixing of laser radiation interacting with an ultracold degenerate ensemble of boson atoms trapped in a magnetic trap. It is shown that the existence of long-range order in this type of atomic system leads to a new mechanism for the generation of the reversed wave whose experimental manifestation should differ from four-wave mixing in a nondegenerate gas. A similar nonlinear optical effect may be used for diagnostics of an ultracold gas at temperatures not much lower than the phase transition temperature. (C) 1999 American Institute of Physics. [S1063-7850(99)02611-7].