General Relativistic Decoherence with Applications to Dark Matter Detection

TL;DR

This paper calculates the rate at which gravitational interactions cause decoherence in quantum systems, revealing that dark matter in the Milky Way remains coherent, which could influence detection methods.

Contribution

It provides the first quantum general relativistic calculation of decoherence rates for superposed metric oscillations, especially applied to dark matter detection.

Findings

Dark matter in the Milky Way is resistant to decoherence.

Superpositions of the dark matter phase are stable, but spatial superpositions are not.

Results may impact future dark matter detection experiments.

Abstract

Quantum mechanics allows for states in macroscopic superpositions, but they ordinarily undergo rapid decoherence due to interactions with their environment. A system that only interacts gravitationally, such as an arrangement of dark matter (DM), may exhibit slow decoherence. In this Letter, we compute the decoherence rate of a quantum object within general relativity, focusing on superposed metric oscillations; a rare quantum general relativistic result. For axion DM in a superposition of the field's phase, we find that DM in the Milky Way is robust against decoherence, while a spatial superposition is not. This novel phase behavior may impact direct detection experiments.