Eight-fold signal amplification of a superconducting nanowire single-photon detector using a multiple-avalanche architecture

Scalable cryogenic readout circuit for a superconducting nanowire single-photon detector system

The superconducting nanowire single-photon detector (SNSPD) is a leading technology for quantum information science applications using photons, and is finding increasing uses in photon-starved classical imaging applications. Critical detector characteristics, such as timing resolution (jitter), reset time, and maximum count rate, are heavily influenced by the readout electronics that sense and amplify the photon detection signal. We describe a readout circuit for SNSPDs using commercial off-the-shelf amplifiers operating at cryogenic temperatures. Our design demonstrates a 35 ps timing resolution and a maximum count rate of over 2 × 10⁷ counts per second, while maintaining <3 mW power consumption per channel, making it suitable for a multichannel readout.

Superconductor-superconductor bilayers for enhancing single-photon detection

Here, we optimized ultrathin films of granular NbN on SiO₂ and of amorphous αW₅Si₃. We showed that hybrid superconducting nanowire single-photon detectors (SNSPDs) made of 2 nm thick αW₅Si₃ films over 2 nm thick NbN films exhibit advantageous coexistence of timing (<5 ns reset time and 52 ps timing jitter) and efficiency (>96% quantum efficiency) performance. We discuss the governing mechanism of this hybridization via the proximity effect. Our results demonstrate saturated SNSPDs performance at 1550 nm optical wavelength and suggest that such hybridization can significantly expand the range of available superconducting properties, impacting other nano-superconducting technologies. Lastly, this hybridization may be used to tune properties, such as the amorphous character of superconducting films.