Quantum dual-path interferometry scheme for axion dark matter searches

Exploring dark matter remains a key quest in modern physics. Detecting axions is challenging due to their weak interactions. This work shows at the quantum level that, in a cavity permeated by a magnetic field, the single axion–photon conversion rate is enhanced by the cavity quality factor and is quantitatively larger than the classical result by 7π/2. The axion cavity behaves as a quantum device emitting single photons with temporal separations, differing from the classical picture. This reveals the possibility to handle signal sensitivity at the quantum level via a dual-path quantum interferometry scheme with cross-power and second-order correlation measurements, greatly reducing signal scanning time and improving sensitivity to the axion–photon coupling, potentially enabling direct axion observation.