Fast and Continuous Detection of Single Microwave Photons via Photo-assisted Quasiparticle Tunneling to a Superconducting Island
arXiv:2511.17470 · doi:10.1103/mj91-ntm4
Abstract
We demonstrate a single-photon detector operating in the microwave domain, based on photo-assisted quasiparticle tunneling events that poison a superconducting island. The detection relies on continuously monitoring the island's charge parity using microwave reflectometry. This scheme achieves 10\% detection efficiency with sub \SI{50}{\ns} time resolution and short dead time ($\sim \SI{1}{\us}$), for microwave photons at \SI{10}{\GHz}. The detector features three junctions connected to a superconducting island, which together carry out photoelectric conversion and charge readout. The enhanced light--matter coupling, crucial to photon to quasiparticle conversion, is provided by a granular aluminum-based high-impedance microwave resonator. The time resolved detection of itinerant microwave photon opens up new perspectives in quantum sensing, microwave quantum optics and mesoscopic physics.
5 pages, 4 figures + supplementary informations