GQuEST: Gravity from the Quantum Entanglement of Spacetime

The GQuEST experiment uses tabletop-scale Michelson laser interferometers to probe for fluctuations in space-time motivated by recent 'geontropic' quantum gravity models. These theories propose that the quantum nature of gravity implies fluctuations of the space-time metric that accumulate over macroscopic distances and yield potentially measurable uncertainties. We present a practicable interferometer design, featuring a novel photon counting readout method that provides unprecedented sensitivity, as it is not subject to the interferometric standard quantum limit. The accelerated accrual of Fisher information offered by the photon counting readout enables GQuEST to detect the predicted quantum gravity phenomena within measurement times at least 100 times shorter than equivalent conventional interferometers. The GQuEST design thus enables a fast and sensitive search for signatures of quantum gravity in a laboratory-scale experiment.