Heterodyne Detection of Axion Dark Matter & Quantum and Classical Effects of Axion Dark Matter

by Dr Kevin Zhou (UC Berkeley)

Thursday 9 Jul 2026, 16:00 → 17:30 Asia/Seoul

C101 (Changjo-gwan, KAIST (Munji Campus))

"Heterodyne Detection of Axion Dark Matter"

Though most axion dark matter experiments use static background fields, the axion also induces transitions between oscillating modes of an excited cavity. This "heterodyne" detection approach benefits from the very high quality factors available in superconducting cavities, and has a parametrically enhanced signal power at low axion masses. I will review recent experimental progress on this concept, which is currently being pursued by groups at SLAC, Fermilab, DESY, CERN, and Peking. In addition, I will show that the heterodyne approach is the strongest method to search for the coupling of ultralight axial vector dark matter to photons.

 

"Quantum and Classical Effects of Axion Dark Matter"

The search for axion dark matter is rapidly expanding, with new experiments deploying quantum sensing techniques to reach unprecedented precision. But does one need to account for the quantum nature of the axion itself? Using concepts developed in quantum optics, I will show that the axion can easily evolve into a quantum state with no classical analogue. But the intrinsically quantum effects of these states are practically undetectable: there always exists a classical ensemble which gives the same detection statistics, up to higher-order corrections in the axion coupling. Thus, the classical field approximation works even when the axion field's state is not classical at all. The same conclusion holds for a variety of other axion effects said to be inherently quantum.

260709_Kevin_Zhou.pdf