Nonperturbative treatment of double Compton backscattering in intense laser fields

Understand

The emission of a pair of entangled photons by an electron in an intense laser field can be described by two-photon transitions of laser-dressed, relativistic Dirac--Volkov states.

• In the limit of a small laser field intensity, the two-photon transition amplitude approaches the result predicted by double Compton scattering theory.
• Multi-exchange processes with the laser field, including a large number of exchanged laser photons, cannot be described without the fully relativistic Dirac--Volkov propagator.
• The nonperturbative treatment significantly alters theoretical predictions for future experiments of this kind.