Nonperturbative treatment of double Compton backscattering in intense laser fields

TL;DR

This paper presents a nonperturbative relativistic approach to modeling double Compton backscattering in intense laser fields, revealing significant differences from perturbative predictions and analyzing photon entanglement.

Contribution

It introduces a fully relativistic, nonperturbative framework using Dirac--Volkov states to accurately describe two-photon emission in intense laser fields, including multi-photon exchange processes.

Findings

Nonperturbative treatment alters theoretical predictions.

Photon entanglement quantified by concurrence.

Results relevant for future high-intensity laser experiments.

Abstract

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. We quantify the degree of polarization correlation of the photons in the final state by employing the well-established concurrence as a measure of the entanglement.