Single-photon detection using high-temperature superconductors

Superconducting single-photon detectors are critical for quantum communication, fluorescence lifetime imaging and remote sensing, but commonly operate at very low temperatures. Now, high-temperature cuprate superconducting nanowires enable single-photon detection up to 25 K. The detection of individual quanta of light is important for quantum communication, fluorescence lifetime imaging, remote sensing and more. Due to their high detection efficiency, exceptional signal-to-noise ratio and fast recovery times, superconducting-nanowire single-photon detectors (SNSPDs) have become a critical component in these applications. However, the operation of conventional SNSPDs requires costly cryocoolers. Here we report the fabrication of two types of high-temperature superconducting nanowires. We observe linear scaling of the photon count rate on the radiation power at the telecommunications wavelength of 1.5 μm and thereby reveal single-photon operation. SNSPDs made from thin flakes of Bi_2Sr_2CaCu_2O_8+ δ exhibit a single-photon response up to 25 K, and for SNSPDs from La_1.55Sr_0.45CuO_4/La_2CuO_4 bilayer films, this response is observed up to 8 K. While the underlying detection mechanism is not fully understood yet, our work expands the family of materials for SNSPD technology beyond the liquid helium temperature limit and suggests that even higher operation temperatures may be reached using other high-temperature superconductors.