Interferometer Response to Geontropic Fluctuations

TL;DR

This paper models quantum gravity vacuum fluctuations as a scalar field with a thermal occupation number and calculates how these 'geontropic' fluctuations affect interferometer measurements, with implications for experiments like LIGO and GQuEST.

Contribution

It introduces a model of vacuum fluctuations in quantum gravity using a scalar field coupled to the metric, and computes the resulting interferometer response.

Findings

Interferometer response to geontropic fluctuations is quantified.

Results are applicable to current and future gravitational wave detectors.

The model links vacuum energy fluctuations to measurable signals.

Abstract

We model vacuum fluctuations in quantum gravity with a scalar field, characterized by a high occupation number, coupled to the metric. The occupation number of the scalar is given by a thermal density matrix, whose form is motivated by fluctuations in the vacuum energy, which have been shown to be conformal near a light-sheet horizon. For the experimental measurement of interest in an interferometer, the size of the energy fluctuations is fixed by the area of a surface bounding the volume of spacetime being interrogated by an interferometer. We compute the interferometer response to these "geontropic" scalar-metric fluctuations, and apply our results to current and future interferometer measurements, such as LIGO and the proposed GQuEST experiment.