Quantum vacuum processes in the extremely intense light of relativistic plasma mirror sources

TL;DR

This paper predicts quantum vacuum effects such as photon-photon scattering and pair creation using intense plasma mirror-generated harmonic beams, demonstrating their potential for experimental observation at unprecedented intensities.

Contribution

It introduces a novel approach using focused harmonic beams from plasma mirrors to probe quantum vacuum processes at extremely high intensities, with detailed numerical predictions and experimental configurations.

Findings

Focused harmonic beams can produce comparable scattering signals to two colliding infrared pulses.

Coupling harmonic beams with auxiliary optical beams enhances inelastic scattering signals.

Quantum vacuum signatures are predicted at intensities between 10^{24} and 10^{28} W/cm^2.

Abstract

The advent of Petawatt-class laser systems allows generating electro-magnetic fields of unprecedented strength in a controlled environment, driving increasingly more efforts to probe yet unobserved processes through their interaction with the quantum vacuum. Still, the lowest intensity scale governing these effects lies orders of magnitude beyond foreseen capabilities, so that such endeavor is expected to remain extremely challenging. In recent years, however, plasma mirrors have emerged as a promising bridge across this gap, by enabling the conversion of intense infrared laser pulses into coherently focused Doppler harmonic beams lying in the X-UV range. In this work, we present quantitative predictions on the quantum vacuum signatures produced when such beams are focused to intensities between $10^{24}$ and $10^{28}\ \mathrm{W.cm}^{-2}$ . These signatures, which notably include photon-photon scattering and electron-positron pair creation, are obtained using state-of-the-art massively parallel numerical tools. In view of identifying experimentally favorable configurations, we also consider the coupling of the focused harmonic beam with an auxiliary optical beam, and provide comparison with other established schemes. Our results show that a single coherently focused harmonic beam can produce as much scattered photons as two infrared pulses in head-on collision, and confirm that the coupling of the harmonic beam to an auxiliary beam gives rise to significant levels of inelastic scattering, and hence holds the potential to strongly improve the attainable signal to noise ratios in experiments.