Harvesting quantum coherence from axion dark matter

TL;DR

This paper proposes a novel method to detect axion dark matter by harvesting quantum coherence using an Unruh-DeWitt detector coupled to the axion field, demonstrating the feasibility of coherence-based detection.

Contribution

It introduces a new coherence harvesting approach with a specific detector model to probe axion dark matter, linking quantum coherence to dark matter detection.

Findings

The detector can harvest quantum coherence from axion dark matter.

A coherence measure formula is derived for a two-level electron system.

The method can determine axion mass via the detector's energy gap.

Abstract

Quantum coherence is one of the most striking features of quantum mechanics rooted in the superposition principle. Recently it has been demonstrated that it is possible to harvest the quantum coherence from a coherent scalar field. In order to explore a new method of detecting axion dark matter, we consider a point-like Unruh-DeWitt detector coupled to the axion field and quantify a coherent measure of the detector. We show that the detector can harvest the quantum coherence from the axion dark matter. To be more precise, we consider a two-level of electron system in an atom as the detector. In this case, we obtain the coherence measure $C=2.2\times 10^{-6}\gamma\, \left(T/1{\rm s}\right)$ where $T$ and $\gamma$ are an observation time and the Lorentz factor. At the same time, the axion mass $m_a$ we can probe is determined by the energy gap of the detector.