Light by light diffraction in vacuum

TL;DR

This paper proposes a method to detect photon-photon scattering in vacuum using laser diffraction, potentially confirming quantum electrodynamics predictions or discovering new physics with current or future high-power lasers.

Contribution

It analytically demonstrates a realistic experimental setup for observing vacuum light-by-light diffraction, improving sensitivity over previous methods and enabling tests of fundamental physics theories.

Findings

Quantum vacuum effects can cause laser beam diffraction.

Single-shot experiments at future 100 PW lasers can detect QED predictions.

Current facilities could discover non-standard physics or improve existing limits.

Abstract

We show that a laser beam can be diffracted by a more concentrated light pulse due to quantum vacuum effects. We compute analytically the intensity pattern in a realistic experimental configuration, and discuss how it can be used to measure for the first time the parameters describing photon-photon scattering in vacuum. In particular, we show that the Quantum Electrodynamics prediction can be detected in a single-shot experiment at future 100 petawatt lasers such as ELI or HIPER. On the other hand, if carried out at one of the present high power facilities, such as OMEGA EP, this proposal can lead either to the discovery of non-standard physics, or to substantially improve the current PVLAS limits on the photon-photon cross section at optical wavelengths. This new example of manipulation of light by light is simpler to realize and more sensitive than existing, alternative proposals, and can also be used to test Born-Infeld theory or to search for axion-like or minicharged particles.