Probing the electromagnetic nonlinearity of vacuum with continuous-wave lasers

TL;DR

This paper proposes a tabletop optical experiment to directly measure the electromagnetic nonlinearity of vacuum, a quantum effect, using resonantly enhanced four-wave mixing at high circulating powers.

Contribution

It introduces a novel experimental setup with resonators reaching high circulating power to detect vacuum nonlinearity predicted by quantum electrodynamics.

Findings

Achieved circulating power of 2.5 MW in a resonator.

Approaching the power level needed to detect EMNV as predicted by QED.

Demonstrated feasibility of the proposed measurement technique.

Abstract

In classical electrodynamics, light waves propagating in vacuum do not interact. In quantum physics, however, photon-photon interactions are mediated by virtual particles, giving rise to the electromagnetic nonlinearity of vacuum (EMNV). A direct measurement of EMNV would test a long-standing prediction of quantum electrodynamics and constrain new physics models. Despite its fundamental significance and extensive efforts to detect it, free-space EMNV has not yet been directly measured in the laboratory. Here, we propose a tabletop all-optical measurement of EMNV based on resonantly enhanced four-wave mixing in focusing optical resonators with a circulating power of a few megawatts. As a key experimental step toward this measurement, we demonstrate a resonator reaching a circulating power of 2.5 MW, approaching the parameter range needed to detect EMNV at the level predicted by quantum electrodynamics.