Decoherence from Long-Range Forces in Atom Interferometry

TL;DR

This paper investigates how long-range forces from ambient particles could cause decoherence in atom interferometers, concluding that such effects are negligible for future experiments, thus supporting their use in fundamental physics tests.

Contribution

The study introduces a Heisenberg picture approach to analyze long-range force effects on atomic coherence, providing a framework to assess decoherence sources in atom interferometry.

Findings

Long-range forces from ambient particles are unlikely to cause significant decoherence.

Decoherence timescales from dark matter backgrounds are estimated to be on the order of years.

The approach allows proper inclusion of experimental apparatus and long-range interactions.

Abstract

Atom interferometers provide a powerful means of realizing quantum coherent systems with increasingly macroscopic extent in space and time. These systems provide an opportunity for a variety of novel tests of fundamental physics, including ultralight dark matter searches and tests of modifications of gravity, using long drop times, microgravity. However, as experiments operate with longer periods of free fall and become sensitive to smaller background effects, key questions start to emerge about the fundamental limits to future atom interferometery experiments. We study the effects on atomic coherence from hard-to-screen backgrounds due to baths of ambient particles with long-range forces, such as gravitating baths and charged cosmic rays. Our approach - working in the Heisenberg picture for the atomic motion - makes proper inclusion of the experimental apparatus feasible and clearly shows how to handle long-range forces and preferred frame ambiguities. We find that these potential backgrounds are likely negligible for the next generation of interferometers, as aggressive estimates for the gravitational decoherence from a background bath of dark matter particles gives a decoherence timescale on the order of years.