# Probing gravity by holding atoms for 20 seconds

## TL;DR

This paper demonstrates a novel atom interferometer that holds atoms for 20 seconds in an optical lattice, enabling highly sensitive gravitational measurements while reducing vibration noise.

## Contribution

It introduces a trapped atom interferometry method with extended interrogation time, surpassing traditional free-fall approaches for gravity probing.

## Key findings

- Achieved 20-second interrogation time with trapped atoms.
- Reduced vibration sensitivity by 3-4 orders of magnitude.
- Measured gravitational potential differences at micron-scale separations.

## Abstract

Atom interferometers are powerful tools for both measurements in fundamental physics and inertial sensing applications. Their performance, however, has been limited by the available interrogation time of freely falling atoms in a gravitational field. We realize an unprecedented interrogation time of 20 seconds by suspending the spatially-separated atomic wavepackets in a lattice formed by the mode of an optical cavity. Unlike traditional atom interferometers, this approach allows potentials to be measured by holding, rather than dropping, atoms. After seconds of hold time, gravitational potential energy differences from as little as microns of vertical separation generate megaradians of interferometer phase. This trapped geometry suppresses the phase sensitivity to vibrations by 3-4 orders of magnitude, overcoming the dominant noise source in atom-interferometric gravimeters. Finally, we study the wavefunction dynamics driven by gravitational potential gradients across neighboring lattice sites.