# Signatures of correlation of spacetime fluctuations in laser interferometers

## TL;DR

This paper explores how laser interferometers can detect spacetime fluctuations predicted by gravity models by analyzing their signal patterns.

## Contribution

The paper introduces a method to link interferometer signals to specific gravity models based on spacetime fluctuation correlations.

## Key findings

- Three classes of spacetime fluctuations are characterized by their correlation functions and frequency behaviors.
- Interferometers with and without arm cavities can detect these fluctuations using different sensitivity ranges.
- Comparing modeled signals with experimental data helps constrain the strength and correlation scale of spacetime fluctuations.

## Abstract

Spacetime fluctuations (SFs), a common feature of proposed gravity models, could be detected using laser interferometers. To advance this effort, we provide the correspondence between expected interferometer output signals and gravity models. We consider three classes of SFs, characterised by the decay behaviours and symmetries of their two-point correlation functions. For each, we identify the low- and high-frequency behaviour of the outputs and their dependence on the interferometer’s length. Capturing these requires sensitivity over a broad frequency range that spans the light-round-trip frequency, as provided by laboratory-scale setups, whereas detecting the presence or absence of SFs can be done with high narrowband sensitivity at the light-round-trip frequency. Our approach applies to interferometers with arm cavities, such as the km-long LIGO detectors, and those without, like laboratory-scale setups QUEST and GQuEST. Finally, we constrain the strength and correlation scale of SFs by comparing our modelled signals with experimental data.

Spacetime fluctuations have been predicted by a plethora of semiclassical and quantum models of gravity. Here, the authors discuss how characteristic signatures of classes of such spacetime fluctuations can be identified in laser interferometers.