Back-reaction on background fields: a coherent state approach

TL;DR

This paper introduces a method to incorporate back-reaction effects of quantum processes on background electromagnetic fields using a coherent state approach, enabling modeling of phenomena like beam depletion in intense laser interactions.

Contribution

It extends background field methods by deforming coherent states to account for back-reaction, providing a new framework for analyzing intense laser-matter interactions.

Findings

Modeling beam depletion via coherent state deformation

Introduction of an extremisation principle for depletion levels

Demonstration of the approach in laser-matter interaction scenarios

Abstract

There are many situations in which a strong electromagnetic field may be approximated as a fixed background. Going beyond this approximation, i.e. accounting for the back-reaction of quantum process on the field, is however challenging. Here we develop an approach to this problem which is a straightforward extension of background field methods. The approach follows from the observation that scattering in an on-shell background is equivalent to scattering between coherent states; we show that by deforming these states one can model back-reaction. Focussing on intense laser-matter interactions, we provide examples which model beam depletion and, furthermore, introduce an extremisation principle with which to determine the level of depletion in a given scattering process.