Matter-Wave Interferometry for Inertial Sensing and Tests of Fundamental Physics

Very Long Baseline Atom Interferometry corresponds to ground-based atomic matter-wave interferometry on large scales in space and time, letting the atomic wave functions interfere after free evolution times of several seconds or wave-packet separation at the scale of meters. As inertial sensors, e.g., accelerometers, these devices take advantage of the quadratic scaling of the leading-order phase shift with the free-evolution time to enhance their sensitivity, giving rise to compelling experiments. With shot-noise-limited instabilities better than 10−9 m/s2 at 1 s at the horizon, Very Long Baseline Atom Interferometry may compete with state-of-the-art superconducting gravimeters, while providing absolute instead of relative measurements. When operated with several atomic states, isotopes, or species simultaneously, tests of the universality of free fall at a level of parts in 1013 and beyond are in reach. Finally, the large spatial extent of the interferometer allows one to probe the limits of coherence at macroscopic scales as well as the interplay of quantum mechanics and gravity. We report on the status of the Very Long Baseline Atom Interferometry facility, its key features, and future prospects in fundamental science.