Signatures of Quantum Gravity in the Gravitational Self-Interaction of Photons

TL;DR

This paper proposes relativistic quantum gravity tests using photon self-interaction in a cavity, revealing signatures that distinguish quantum gravity effects from classical theories, and offering new ways to explore gravity's quantum nature.

Contribution

It introduces a novel experimental scheme to detect quantum gravitational signatures via photon self-interaction, sensitive to graviton spin and locality, free from QED photon-photon scattering.

Findings

Quantum gravitational signatures alter photon states in a measurable way.

The proposed tests are sensitive to graviton spin and the locality of gravity.

Measurement schemes can optimally detect quantum gravity effects.

Abstract

We propose relativistic tests of quantum gravity using the gravitational self-interaction of photons in a cavity. We demonstrate that this interaction results in a number of quantum gravitational signatures in the quantum state of the light that cannot be reproduced by any classical theory of gravity. We rigorously assess these effects using quantum parameter estimation theory, and discuss simple measurement schemes that optimally extract their signatures. Crucially, the proposed tests are free of QED photon-photon scattering, are sensitive to the spin of the mediating gravitons, and can probe the locality of the gravitational interaction. These protocols provide a new avenue for studying the quantum nature of gravity in a relativistic setting.