Reaching supercritical field strengths with intense lasers

TL;DR

This paper investigates how oblique laser-electron collisions can enable electrons to reach supercritical QED field strengths, highlighting the role of collision angle in mitigating energy losses and facilitating the study of quantum electrodynamics breakdown.

Contribution

It demonstrates that oblique collisions between high-energy electron beams and intense lasers can achieve supercritical fields, providing a practical approach for experimental exploration of strong-field QED.

Findings

Oblique incidence reduces photon emission energy losses.

Electrons with tens of GeV can reach supercritical fields at $10^{24}~\text{W}\text{cm}^{-2}$ intensity.

Certain quantum effects are enhanced at oblique incidence.

Abstract

It is conjectured that all perturbative approaches to quantum electrodynamics (QED) break down in the collision of a high-energy electron beam with an intense laser, when the laser fields are boosted to `supercritical' strengths far greater than the critical field of QED. As field strengths increase toward this regime, cascades of photon emission and electron-positron pair creation are expected, as well as the onset of substantial radiative corrections. Here we identify the important role played by the collision angle in mitigating energy losses to photon emission that would otherwise prevent the electrons reaching the supercritical regime. We show that a collision between an electron beam with energy in the tens of GeV and a laser pulse of intensity $10^{24}~\text{W}\text{cm}^{-2}$ at oblique, or even normal, incidence is a viable platform for studying the breakdown of perturbative strong-field QED. Our results have implications for the design of near-term experiments as they predict that certain quantum effects are enhanced at oblique incidence.