Quantum statistical properties of the radiation field in the degenerate two-photon emission process

The degenerate two-photon emission process is treated on the basis of quantum theory. Neglecting relaxation mechanisms, solutions in short time approximation are given. Relevant quantities as the mean photon number, second order correlation, field fluctuations and the uncertainty product are analyzed. It is shown, that an initial coherent state does not tend to a two-photon coherent state by two-photon emission as it can be expected from the results given by Yuen.