# Energy absorption in the laser-QED regime

## TL;DR

This paper investigates how energy absorption in ultra-intense laser interactions changes when quantum electrodynamics effects become significant, predicting a regime shift linked to pair production, verified through simulations.

## Contribution

It introduces a theoretical prediction of a regime change in laser energy absorption due to QED effects, confirmed by extensive numerical simulations.

## Key findings

- Regime change in electron energy dependence at QED threshold
- Power law shift associated with pair production onset
- Potential experimental signature for entering the QED regime

## Abstract

A theoretical and numerical investigation of non-ponderomotive absorption at laser intensities relevant to quantum electrodynamics is presented. It is predicted that there is a regime change in the dependence of fast electron energy on incident laser energy that coincides with the onset of pair production via the Breit-Wheeler process. This prediction is numerically verified via an extensive campaign of QED-inclusive particle-in-cell simulations. The dramatic nature of the power law shift leads to the conclusion that this process is a candidate for an unambiguous signature that future experiments on multi-petawatt laser facilities have truly entered the QED regime.