  We show that photon coincidence spectroscopy can provide an unambiguous
signature of two atoms simultaneously interacting with a quantised cavity field
mode. We also show that the single-atom Jaynes-Cummings model can be probed
effectively via photon coincidence spectroscopy, even with deleterious
contributions to the signal from two-atom events. In addition, we have
explicitly solved the eigenvectors and eigenvalues of two two-level atoms
coupled to a quantised cavity mode for differing coupling strengths.
