Coincidence detection of single photons is crucial in numerous quantum technologies and usually requires multiple time-resolved single-photon detectors. However, the electronic readout becomes a major challenge when the measurement basis scales to large numbers of spatial modes. Here, we address this problem by introducing a two-terminal coincidence detector that enables scalable readout of an array of detector segments based on superconducting nanowire microstrip transmission line. Exploiting timing logic, we demonstrate a 16-element detector that resolves all 136 possible single-photon and two-photon coincidence events. We further explore the pulse shapes of the detector output and resolve up to four-photon coincidence events in a 4-element device, giving the detector photon-number-resolving capability. This new detector architecture and operating scheme will be particularly useful for multi-photon coincidence detection in large-scale photonic integrated circuits.
@article{arxiv.1711.10546,
title = {A scalable multi-photon coincidence detector based on superconducting nanowires},
author = {Di Zhu and Qing-Yuan Zhao and Hyeongrak Choi and Tsung-Ju Lu and Andrew E. Dane and Dirk R. Englund and Karl K. Berggren},
journal= {arXiv preprint arXiv:1711.10546},
year = {2018}
}