Multiphoton emission spectrum of two atoms interacting with two modes of radiation field

The multiphoton emission spectrum of a pair of coupling two-level atoms interacting with two modes of the radiation field is studied. A general expression for the two-mode multiphoton emission spectrum is presented. The non-degenerate two-photon emission spectra of two atoms are calculated when the two modes of the field are in various number states and some new results are obtained. It is found that the two-atom emission spectrum in the two-mode vacuum field reflects the atomic dipole-dipole interaction more sensitively than in the case of a single-mode vacuum field.