SNSPDs function based on the principle of superconductivity and the photonic interaction with the nanowire. When a photon strikes the superconducting nanowire, it creates a localized region of normal (non-superconducting) resistance. This disruption in the superconducting state generates a measurable voltage pulse, indicating the detection of a single photon. The nanowire is then reset to its superconducting state, ready to detect the next photon.
