A Superconducting Tunable Cavity for Axion Dark Matter Detection in the Microwave Regime

Dark matter candidates, such as the axion or hidden photon, could convert to light. Current dark matter searches based on resonant cavities coherently accumulate the field sourced by the dark matter at fixed frequencies and use a near-quantum limited amplifier to read out the cavity signal. The capability of in-situ frequency tuning of the resonant cavity will be a powerful tool to scan through the relevant axion mass range effectively. Here, we present the development of a tunable cavity architecture using a superconducting quantum interference device (SQUID) through dc flux-biasing while maintaining a good coherence time, allowing us to perform a dark matter mass range scan close to quantum limited noise. We also employ a robust microwave photon counting technique through repeated quantum nondemolition measurements harnessing a transmon qubit for hidden-photon dark matter detection [1].