Photon vortex generation from nonlinear Compton scattering in Feynman approach

TL;DR

This paper models nonlinear Compton scattering with circularly polarized light using Feynman diagrams, demonstrating photon vortex generation with specific angular momentum properties and analyzing the effects of electron spin flips.

Contribution

It introduces a Feynman diagram approach to calculate photon vortex generation in nonlinear Compton scattering, considering angular momentum conservation and spin effects.

Findings

Photon vortices with specific angular momentum are predominantly generated when electrons absorb multiple photons.

Spin flip contributions to vortex generation are negligible, about four orders of magnitude smaller.

Circular polarization influences the properties of the generated photon vortices.

Abstract

In the present study, we show calculation of nonlinear Compton scattering with circularly polarized photons in a cylindrical coordinate using Feynman diagram to calculate photon vortex generation in intermediate states considering conservation of angular momentum. We take two different vortex wave functions based on Bessel function for the emitted photon and the electron after emission of the photon, which are the eigenstate of z component of the total angular momentum (zTAM) when a particle propagates along z axis. The result shows that when an electron absorbs N photons a photon vortex with a zTAM = N is predominantly radiated, but there are still very small contributions of photons with a zTAM = (N-1) and (N +1) due to the spin flip of the initial electron. This means even when an electron absorbs only a single photon, the electron may emit a photon vortex of a zTAM of 2 h-bar. However, the numerical calculations show that the contribution of the spin flip is four orders of magnitude smaller than that of the dominant radiation. We also discuss the circular polarization for the generated photon vortices.