Saturating Intrinsic Detection Efficiency of Superconducting Nanowire Single-Photon Detectors via Defect Engineering

Superconducting nanowire single-photon detectors (SNSPDs) with high system detection efficiency (SDE) would enable remarkable experiments in quantum information processing. However, realizing a NbN SNSPD with saturated intrinsic detection efficiency (IDE) that retains high SDE at near-infrared wavelengths is challenging, due to the high critical temperature of NbN. This study uses defect engineering by helium-ion irradiation to enhance the IDE of NbN SNSPDs to saturation without sacrificing SDE. This technique also allows direct comparison of irradiation-induced changes in detector performance, making it a useful tool for studying the physics of superconducting devices.