Superconducting single-photon detector with a speed of 5 GHz and a photon number resolution of 61

Abstract

Rapid detection and discrimination of single photons are pivotal in various applications, such as deep-space laser communication, high-rate quantum key distribution, and optical quantum computation. However, conventional single-photon detectors (SPDs), including semiconducting and recently developed superconducting detectors, have limited detection speed and photon number resolution (PNR), which pose significant challenges in practical applications. In this paper, we present an efficient, fast SPD with good PNR, which has 64 paralleled, sandwiched superconducting nanowires fabricated on a distributed Bragg reflector. The detector is operated in a compact Gifford–McMahon cryocooler that supports 64 electrical channels and has a minimum working temperature of 2.3 K. The combined detector system shows a functional nanowire yield of 61/64, a system detection efficiency of 90% at 1550 nm, and a maximum count rate of 5.2 GHz. Additionally, it has a maximum PNR of 61, corresponding to the operating nanowires. This SPD signifies a substantial improvement in quantum detector technology, with potential applications in deep-space laser communication, high-speed quantum communication, and fundamental quantum optics experiments.