Generation and detection of two-photon coherent states in degenerate four-wave mixing

It is shown that degenerate four-wave mixing generates two-photon coherent states (TCS) of the radiation field for modes that are proper combinations of the output object and image waves. TCS light has novel quantum behavior, which can be probed by homodyne detection, intensity interferometry, or photocount statistics. Numerical estimates indicate that the generation and detection of TCS light via degenerate four-wave mixing and homodyne detection can be accomplished with current technology.