Intrinsically Quantum Effects of Axion Dark Matter are Undetectable
Abstract
Is the usual treatment of axion dark matter as a classical field reliable? We show that the answer is subtle: the axion field could well be in a quantum state that has no complete classical description, but realistic detectors cannot tell the difference. To see this, we solve a fully quantum model of axion detection using quantum optics techniques. We show that intrinsically quantum effects are washed out by mode averaging or small amounts of noise, and significantly suppressed by the weakness of the axion coupling. Our work exemplifies that there should always be a classical analog for axion dark matter effects, extends to other wave (ultralight) dark-matter candidates, and gives a general method to compute the effects of exotic dark-matter states.
Cite
@article{arxiv.2510.05198,
title = {Intrinsically Quantum Effects of Axion Dark Matter are Undetectable},
author = {Yunjia Bao and Dhong Yeon Cheong and Nicholas L. Rodd and Joey Takach and Lian-Tao Wang and Kevin Zhou},
journal= {arXiv preprint arXiv:2510.05198},
year = {2025}
}
Comments
10 pages, 1 figure