Coherence limits in lattice atom interferometry at the one-minute scale

TL;DR

This paper demonstrates an atom interferometer maintaining spatial superpositions for up to 70 seconds, significantly exceeding previous limits, and analyzes the coherence limits due to collective dephasing, opening new possibilities for precision measurements.

Contribution

It introduces a long-duration atom interferometer with enhanced coherence times and provides a theoretical and experimental analysis of decoherence mechanisms at these timescales.

Findings

Coherence maintained for up to 70 seconds in atom interferometry.

Decoherence rate slows down at hold times exceeding tens of seconds.

Potential applications in gravimetry and fundamental physics tests.

Abstract

In quantum metrology and quantum simulation, a coherent non-classical state must be manipulated before unwanted interactions with the environment lead to decoherence. In atom interferometry, the non-classical 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 around 3 seconds for a 10 m fountain. Here, we realise an atom interferometer with a spatial superposition state that is maintained for as long as 70 seconds. We analyse the theoretical and experimental limits to coherence arising from collective dephasing of the atomic ensemble. This reveals that the decoherence rate slows down markedly at hold times that exceed tens of seconds. These gains in coherence may enable gravimetry measurements, searches for fifth forces or fundamental probes into the non-classical nature of gravity.