Double-slit vacuum polarisation effects in ultra-intense laser fields

TL;DR

This paper explores how ultra-intense laser fields induce vacuum polarisation effects that cause light-by-light diffraction, interference patterns, and polarization changes in a probe laser, revealing potential observable quantum vacuum phenomena.

Contribution

It introduces a novel double-slit-like setup with counter-propagating laser pulses to study vacuum polarisation effects and calculates observable diffraction and polarization signals.

Findings

Demonstrates a light-by-light diffraction pattern similar to double-slit experiments.

Calculates the number of diffracted probe photons and regions with enhanced vacuum signals.

Shows that beam misalignment can increase observable effects under certain conditions.

Abstract

The influence of the strong laser-driven vacuum on a propagating electromagnetic probe wave has been studied in detail. We investigate two scenarios comprising a focused probe laser beam passing through a region of vacuum polarised by an ultra-intense laser field. By splitting this strong field into two, separated, monochromatic Gaussian pulses counter-propagating in a plane perpendicular to the probe field axis, we demonstrate a leading order light-by-light diffraction effect that generates an interference pattern reminiscent of the classic double-slit experiment. We calculate the total number of probe photons diffracted as well as the number diffracted into regions where the vacuum polarisation signal is higher than the probe background. In addition, we calculate the induced ellipticity and polarisation rotation in the probe beam and show how, in the realistic situation in which the centres of the two strong fields are not exactly aligned, certain ranges of beam separation and observation distance may actually lead to an increase over the idealised case of a single strong laser beam.