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 Letter 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.
Fields of Study & Subjects
Dark Matter and Cosmic Phenomena
Atomic and Subatomic Physics Research
Chemical and Physical Properties of Materials
Publication details
- Journal / source
- Physical Review Letters
- Publisher
- American Physical Society (APS)
- Volume
- 136
- Issue
- 17
- Publication date
- 31 March 2026
- Language
- EN