Single photon detectors operate based on various mechanisms, including avalanche photodiodes (APDs), superconducting nanowires, and photomultiplier tubes (PMTs). These mechanisms rely on the interaction of photons with the detector material to generate an electrical signal. For instance, in avalanche photodiodes, a single photon can trigger a cascade of electrons, resulting in a detectable current pulse. The choice of mechanism depends on the specific application and desired sensitivity.
