Single-Photon Single-Flux Coupled Detectors

In this work, we present a novel device that is a combination of a superconducting nanowire single-photon detector and a superconducting multilevel memory. We show that these devices can be used to count the number of detections through single-photon to single-flux conversion. Electrical characterization of the memory properties demonstrates single-flux quantum (SFQ) separated states. Optical measurements using attenuated laser pulses with different mean photon number, pulse energies and repetition rates are shown to differentiate single-photon detection from other possible phenomena, such as multiphoton detection and thermal activation. Finally, different geometries and material stacks to improve device performance, as well as arraying methods, are discussed.