Minute-scale gravimetry using a coherent atomic spatial superposition

Abstract

In quantum metrology and quantum information processing, a coherent nonclassical state must be manipulated before unwanted interactions with the environment lead to decoherence. In atom interferometry, the nonclassical state is a spatial superposition, where each atom coexists in multiple locations as a collection of phase-coherent partial wavepackets. These states enable precise measurements in fundamental physics and inertial sensing. However, atom interferometers usually use atomic fountains, where the available interrogation time is limited to ~3 seconds (for 10 m fountains). Here, we analyze the theoretical and experimental limits to the coherence arising from collective dephasing of the atomic ensemble and realize atom interferometry with a spatial superposition state that is maintained for as long as 70 seconds. These gains in coherence may enable gravimetry measurements, searches for fifth forces, or fundamental probes into the non-classical nature of gravity.Comment: 21 pages, 9 figure