Measuring Vacuum Polarisation with High Power Lasers
B. King, T. Heinzl
TL;DR
Measuring Vacuum Polarisation with High Power Lasers addresses how the quantum vacuum acts as a nonlinear medium under strong fields, enabling real photon-photon scattering observations. It surveys three analytical frameworks—S-matrix with a background, the polarization operator, and the Heisenberg-Euler modified Maxwell equations—and demonstrates their equivalence for predicting laser-based experiments. It catalogs a broad range of observable signatures across polarization, wavevector, frequency, and pulse shape, including vacuum birefringence, diffraction, frequency shifts, high-harmonics, and photon splitting, with sample parametric estimates. It advocates that upcoming high-power laser facilities and cavity-based schemes could realize the first measurements of real photon-photon scattering, connecting theoretical predictions to practical experimental tests.
Abstract
When exposed to intense electromagnetic fields, the quantum vacuum is expected to exhibit properties of a polarisable medium akin to a weakly nonlinear dielectric material. Various schemes have been proposed to measure such vacuum polarisation effects using a combination of high power lasers. Motivated by several planned experiments, we provide an overview of experimental signatures that have been suggested to confirm this prediction of quantum electrodynamics of real photon-photon scattering.