Superconducting nanowire single-photon detectors (SNSPDs) are highly sensitive devices used to detect individual photons, which are the smallest units of light. They operate at very low temperatures, close to absolute zero, where certain materials become superconductors. When a photon hits the nanowire, it creates a localized area of resistance, allowing the detection of the photon. SNSPDs are known for their high efficiency and fast response times, making them valuable in various applications, including quantum computing and quantum cryptography. Their ability to detect single photons with minimal noise makes them superior to traditional detectors in many scenarios.