Investigation of Resonant Activation in a Josephson Junction for Axion Search With Microwave Single Photon Detection

A growing interest in the detection of single microwave-photons has been stimulated by the search for light dark matter, such as Axions and Axion-like particles, together with the fast development of quantum technologies based on superconducting devices. Many solutions have been proposed in literature but most of them still fail to satisfy the tight requirements imposed by Dark Matter experiments. For instance, many have a large dark-count rate that still make parametric amplifiers a preferable choice. On the contrary, a device based on a current biased Josephson junction resonantly activated by the absorption of a microwave photon may have dark-counts rate down to the mHz level. Here, we report the experimental study of the resonant activation of an Al Josephson junction excited by continuous radiofrequency. The device under study consists of a chip with a transmission line terminated by an Al Josephson-junction, fabricated by shadow-mask evaporation technique. The sample-holder with the chip inside is hosted in a superconducting box and it is thermally anchored to the mixing-chamber plate of a dilution refrigerator at a temperature of about 15 mK. We measured the escape rates of the junction in different configurations of current bias and radiofrequency excitations. Response to continuous wave has been measured and interpreted within the RCSJ model. These results are used to optimize the design of a single microwave-photon detector.