Enhanced Detection\nRate and High Photon-Number Efficiencies\nwith a Scalable Parallel SNSPD

Since their inception, superconducting nanowire single-photon\ndetectors\nhave been enabling quantum optical applications and the rise of the\nphotonic quantum industry. The evolution in the detector design and\nread-out strategies has led to the introduction of devices with a\nplurality of independent pixels, which have been able to operate with\nhigh system detection efficiency at high speed while also supporting\nphoton number resolution capabilities. However, this comes at the\ncost of a complex readout that requires one coaxial cable for each\npixel of the array. Here, we report a 28-pixel SNSPD with a dedicated\nparallel architecture that, while maintaining a simple readout with\na single coaxial line, enables the detector to operate at high speed\nwith low-performance degradation. The device shows a maximum single-photon\nefficiency of 88% and is able to maintain its efficiency above 50%,\ncoupled with a timing jitter lower than 80 ps, up to a detection rate\nof 200 million counts per second. The detector also provides state-of-the-art\nphoton-number-resolving performances with a 2-photon efficiency of\n75% and a 3-photon efficiency of 62%.