Quantum sensing of axion dark matter with a phase resolved haloscope

Axions are hypothetical particles which do not belong to the standard model. They are credible candidates for dark matter in the Universe. Under a high DC magnetic field, an axion can decay into a photon of energy corresponding to the axion mass. Three-dimensional cavities in high magnetic fields can therefore serve as axion detectors, as first proposed by P. Sikivie in 1983. These devices, known as cavity haloscopes, are limited to a narrow range of accessible frequencies as opposed to the wide range of possible axion masses. Their sensitivity is also bounded by the standard quantum limit, which has slowed down the axion dark matter sensing efforts so far.

Our haloscope is different in concept from the existing platform, as it combines a superconducting circuit, an antiferromagnetic crystal, and a microwave cavity. It aims to detect the axion signal by measuring a phase shift of the microwave signal, which can outcast the standard quantum limit. Furthermore, the antiferromagnetic crystal provides a tunability, enabling in principle a large mass range.

In my talk, I will present our results concerning the physics of the superconducting circuit, the antiferromagnetic and the cavity modes. I will also show that our hybrid magnon-superconducting circuit-cavity platform is a scanning phase haloscope which should enable a substantial speed-up in the axion dark matter search, I will show recent measurements on sub-Poissonian distribution for quantum spectroscopy.