A superconducting nanowire single-photon camera with 400,000 pixels

For the past 50 years, superconducting detectors have offered exceptional sensitivity and speed for detecting faint electromagnetic signals in a wide range of applications. These detectors operate at very low temperatures and generate a minimum of excess noise, making them ideal for testing the non-local nature of reality^1,2, investigating dark matter^3,4, mapping the early universe^5-7 and performing quantum computation^8-10 and communication^11-14. Despite their appealing properties, however, there are at present no large-scale superconducting cameras-even the largest demonstrations have never exceeded 20,000 pixels¹⁵. This is especially true for superconducting nanowire single-photon detectors (SNSPDs)^16-18. These detectors have been demonstrated with system detection efficiencies of 98.0% (ref. ¹⁹), sub-3-ps timing jitter²⁰, sensitivity from the ultraviolet²¹ to the mid-infrared²² and microhertz dark-count rates³, but have never achieved an array size larger than a kilopixel^23,24. Here we report on the development of a 400,000-pixel SNSPD camera, a factor of 400 improvement over the state of the art. The array spanned an area of 4 × 2.5 mm with 5 × 5-μm resolution, reached unity quantum efficiency at wavelengths of 370 nm and 635 nm, counted at a rate of 1.1 × 10⁵ counts per second (cps) and had a dark-count rate of 1.0 × 10^-4 cps per detector (corresponding to 0.13 cps over the whole array). The imaging area contains no ancillary circuitry and the architecture is scalable well beyond the present demonstration, paving the way for large-format superconducting cameras with near-unity detection efficiencies across a wide range of the electromagnetic spectrum.