Energy absorption in the laser-QED regime

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 teh dependence of fast electron energy on incident laser energy that coincides with teh onset of pair production via the Breit-Wheeler process. This prediction is numerically verified via na extensive campaign of QED-inclusive particle-in-cell simulatoins. 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.