  The three-photon Compton effect is studied. An incoming photon undergoes
triple scattering off a free electron, which leads to the emission of three
entangled photons. We investigate the properties of both the total cross
section, assuming a low-energy cutoff for the detected photons, and the
differential cross section. Particular emphasis is laid on evaluating
polarization-resolved cross sections. The entanglement of the final
three-photon state is analyzed.
