Precision measurement of gravity in a lattice atom interferometer

Atom interferometers are powerful quantum metrology devices to study fundamental physics and perform inertial sensing. However, they use atoms in free-fall, which limits measurement time to a few seconds or even less when measuring highly localized potentials due to small source masses. We instead realize interferometers with atoms suspended for up to 70 seconds in an optical lattice. In a recent measurement, we optimize the gravitational sensitivity of a lattice interferometer and use a system of signal inversions and switches to suppress and quantify systematic effects. We measure the attraction of a miniature source mass to be a_mass = 33.3 ± 5.6_stat ± 2.7_syst nm/s², consistent with Newtonian gravity, ruling out the existence of screened dark energy theories over their natural parameter space. More importantly, the combined accuracy of 6.2 nm/s² is four times as good as the best similar measurements with freely falling atoms, demonstrating the advantages of lattice interferometry in fundamental physics measurements. Improved atom-cooling and tilt-noise suppression may enable even higher sensitivity in a table-top setup, allowing the measurement of forces at sub-millimeter ranges, compact gravimetry, measuring the gravitational Aharonov-Bohm effect and the gravitational constant, and testing whether the gravitational field itself has quantum properties.