Low-noise single-photon counting superconducting nanowire detectors at infrared wavelengths up to 29 μm

We report on the extension of the spectral sensitivity of superconductingnanowire single-photon detectors to a wavelength of 29 μm.This represents the first demonstration of a time correlated singlephotoncounting detector at these long infrared wavelengths. We achievesaturated internal detection efficiency from 10 to 29 μm, whilst maintainingdark count rates below 0.1 counts per second. Extensionof superconducting nanowire single-photon detectors to this spectralrange provides low noise and high timing resolution photon countingdetection, effectively providing a new class of single-photon sensitivedetector for these wavelengths. These detectors are importantfor applications such as exoplanet spectroscopy, infrared astrophysics,physical chemistry, remote sensing and direct dark-matter detection.