Impedance-matched differential superconducting nanowire detectors

Superconducting nanowire single-photon detectors (SNSPDs) are the highest performing photon-counting technology in the near-infrared (NIR). Due to delay-line effects, large area SNSPDs typically trade-off timing resolution and detection efficiency. 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-to-single-ended readout electronics, with minimal impact on the system timing resolution. Our niobium nitride differential SNSPDs achieve \(47.3\,\% \pm 2.4\,\%\) system detection efficiency and sub-\(10\,\mathrm{ps}\) system jitter at \(775\,\mathrm{nm}\), while at \(1550\,\mathrm{nm}\) they achieve \(71.1\,\% \pm 3.7\,\%\) system detection efficiency and \(13.1\,\mathrm{ps} \pm 0.4\,\mathrm{ps}\) system jitter. These detectors also achieve sub-100 ps timing response at one one-hundredth maximum level, \(30.7\,\mathrm{ps} \pm 0.4\,\mathrm{ps}\) at \(775\,\mathrm{nm}\) and \(47.6\,\mathrm{ps} \pm 0.4\,\mathrm{ps}\) at \(1550\,\mathrm{nm}\), enabling time-correlated single-photon counting with high dynamic range response functions. Furthermore, thanks to 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 many scientific applications.