High-time-resolved 64-channel single-flux quantum-based address encoder integrated with a multi-pixel superconducting nanowire single-photon detector.

We propose and demonstrate a 64-channel event-driven encoder based on single-flux quantum (SFQ) circuits for application to a multi-pixel superconducting nanowire single-photon detector (SSPD) system. Multi-pixel SSPD systems were developed to improve maximum count rates and realize ultra-sensitive imaging systems. An intelligent signal processor is required, which we designed based on SFQ circuits. We were able to obtain an address based on the reserve timing information for the photon detection that occurs in the SSPD, as well as read the time-tagged address information for the SSPDs through the SFQ encoder. The overall observed FWHM jitter was 56.5 ps.