# Exploring gravity with the MIGA large scale atom interferometer

## TL;DR

This paper proposes an underground large-scale atom interferometer to detect gravitational waves in a frequency band not covered by existing observatories, using innovative hybrid atom-laser technology for enhanced sensitivity.

## Contribution

It introduces a novel large-scale atom interferometer design for gravitational wave detection, demonstrating its potential sensitivity and operational principles at an underground site.

## Key findings

- Projected strain sensitivity of 2×10^{-13}/√Hz at 2 Hz
- Design of a hybrid atom-laser antenna for gravitational wave detection
- Assessment of underground site for low-noise measurements

## Abstract

We present an underground long baseline atom interferometer to study gravity at large scale. The hybrid atom-laser antenna will use several atom interferometers simultaneously interrogated by the resonant mode of an optical cavity. The instrument will be a demonstrator for gravitational wave detection in a frequency band (100 mHz - 1 Hz) not explored by classical ground and space-based observatories, and interesting for potential astrophysical sources. In the initial instrument configuration, standard atom interferometry techniques will be adopted, which will bring to a peak strain sensitivity of 2$\cdot 10^{-13}/\sqrt{\mathrm{Hz}}$ at 2 Hz. The experiment will be realized at the underground facility of the Laboratoire Souterrain \`a Bas Bruit (LSBB) in Rustrel--France, an exceptional site located away from major anthropogenic disturbances and showing very low background noise. In the following, we present the measurement principle of an in-cavity atom interferometer, derive signal extraction for Gravitational Wave measurement from the antenna and determine the expected strain sensitivity. We then detail the functioning of the different systems of the antenna and describe the properties of the installation site.