Effect of the wire width on the intrinsic detection efficiency of superconducting-nanowire single-photon detectors

TL;DR

This study investigates how the width of superconducting nanowires affects their ability to detect single photons, revealing that the efficiency cutoff correlates with wire width and aligns with hot-spot detection models.

Contribution

It provides a spectral analysis linking wire width to detection efficiency and compares hot-spot and vortex-assisted models for explaining the cutoff behavior.

Findings

Cut-off wavelength scales inversely with wire width.

Hot-spot models accurately predict the scaling behavior.

Vortex-assisted models suggest a stronger dependence on wire width.

Abstract

Thorough spectral study of the intrinsic single-photon detection efficiency in superconducting TaN and NbN nanowires with different widths shows that the experimental cut-off in the efficiency at near-infrared wavelengths is most likely caused by the local deficiency of Cooper pairs available for current transport. For both materials the reciprocal cut-off wavelength scales with the wire width whereas the scaling factor quantitatively agrees with the hot-spot detection models. Comparison of the experimental data with vortex-assisted detection scenarios shows that these models predict a stronger dependence of the cut-off wavelength on the wire width.