We investigate both the electrical response of Superconducting Single Photon Detectors (SSPDs) and the critical behaviour behind the superconducting phase transition. It is found that the existence...Show moreWe investigate both the electrical response of Superconducting Single Photon Detectors (SSPDs) and the critical behaviour behind the superconducting phase transition. It is found that the existence of the intermediate state and corresponding relaxation oscillations are paramount for the self-reset of SSPDs and resulting photon detection. The superconducting transition in the discussed SSPDs is set by the thermal unbinding of vortices following the behaviour set by the BKT phase transition. However, the critical behaviour at low temperatures is set by the depairing of Cooper pairs which is the dominant process.Show less
