Theoretical study of the Compton effect with correlated three-photon   emission: From the differential cross section to high-energy triple-photon   entanglement
  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. 
E. L\"otstedt, U. D. Jentschura
quant-ph