Impedance-Matched Differential Superconducting Nanowire Detectors

Superconducting nanowire single-photon detectors (SNSPDs) are the highest-performing photoncounting technology in the near-infrared region. Because of delay-line effects, large-area SNSPDs typically trade off timing resolution and detection efficiency. This unavoidable fundamental constraint might limit their future deployment in demanding scientific applications. Here we introduce a detector design based on transmission-line engineering and differential readout for device-level signal conditioning, enabling a high system detection efficiency and a low detector jitter simultaneously. To make our differential detectors compatible with single-ended time taggers, we also engineer analog differential-tosingle-ended readout electronics, with minimal impact on the system timing resolution. Our best niobium nitride differential SNSPD achieves a system detection efficiency of (83.3 +/- 4.3)% at 1550 nm and (78 +/- 5)% at 775 nm. The lowest system jitter is 13.0 +/- 0.4 ps at 1550 nm and 9.7 +/- 0.4 ps at 775 nm, limited by intrinsic contributions. These detectors also achieve sub-100-ps timing response at 1/100 of the maximum level, 30.7 +/- 0.4 ps at 775 nm and 47.6 +/- 0.4 ps at 1550 nm, enabling time-correlated single-photon counting with high-dynamic-range response functions. Furthermore, because of the differential impedance-matched design, our detectors exhibit delay-line imaging capabilities and photon-number resolution. The properties and high-performance metrics achieved by our system make it a versatile photon-detection solution for quantum computing, quantum communication, and many other scientific applications.