Fractal Superconducting Nanowires Detect Infrared Single Photons with 84% System Detection Efficiency, 1.02 Polarization Sensitivity, and 20.8 ps Timing Resolution

The near-unity system detection efficiency (SDE) and excellent timing resolution of superconducting nanowire single-photon detectors (SNSPDs), combined with their other merits, have enabled many classical quantum photonic applications. However, the prevalent design based on meandering nanowires makes SDE dependent polarization states incident photons; for unpolarized light, major merit high would get compromised, which could be detrimental photon-starved Here, we create SNSPDs an arced fractal geometry that almost completely eliminates this dependence SDE, experimentally demonstrate 84$\pm$3$\%$ 1.02$^{+0.06}_{-0.02}$ sensitivity at wavelength 1575 nm, 20.8 ps jitter in a 0.1-W closed-cycle Gifford-McMahon cryocooler, base temperature 2.0 K. This demonstration provides novel, practical device structure SNSPDs, allowing operation visible, near-, mid-infrared spectral ranges, paves way polarization-insensitive