Stochasticity effects in quantum radiation reaction

TL;DR

This paper demonstrates that quantum stochastic effects in radiation reaction cause electron beams to spread out after laser interaction, contrasting classical predictions, and suggests these effects are experimentally observable with current technology.

Contribution

It reveals the opposite effect of quantum stochasticity on electron beam dynamics compared to classical models, highlighting the importance of quantum effects in radiation reaction.

Findings

Quantum stochasticity causes electron beam spreading.

Simulations show effects are measurable with current lasers.

Quantum effects dominate in high-intensity laser-electron interactions.

Abstract

When an ultrarelativistic electron beam collides with a sufficiently intense laser pulse, radiation-reaction effects can strongly alter the beam dynamics. In the realm of classical electrodynamics, radiation reaction has a beneficial effect on the electron beam as it tends to reduce its energy spread. Here, we show that when quantum effects become important, radiation reaction induces the opposite effect, i.e., the electron beam spreads out after interacting with the laser pulse. We identify the physical origin of this opposite tendency in the intrinsic stochasticity of photon emission, which becomes substantial in the full quantum regime. Our numerical simulations indicated that the predicted effects of the stochasticity can be measured already with presently available lasers and electron accelerators.