Dark Counts in Superconducting Single-photon NbN/NiCu Detectors

Nanostripes of hybrid superconductor/ferromagnetic (S/F) NbN/NiCu bilayers and pure superconducting NbN nanostripes have been investigated in dark count experiments. Presence of a ferromagnetic layer influences the superconducting properties of the S/F bilayer, such as the critical current density and the transient photoresponse. The observed significant decrease of the dark-count rate is discussed in terms of vortex-related fluctuation models to shed more light in the intriguing question of the basic mechanism responsible for dark counts in superconducting nanostripe single photon detectors