Experimental observation of anomalous supralinear response of single-photon detectors

TL;DR

This paper reports the first precise measurement of nonlinear responses in single-photon detectors, revealing unexpected supralinear behavior that challenges existing models and enhances understanding of detector anomalies.

Contribution

It introduces a novel measurement approach and uncovers previously unknown supralinear effects in single-photon detectors, expanding the knowledge of their nonlinear behavior.

Findings

Discovery of supralinear response in avalanche diodes

Full characterization of superconducting nanowire detectors

Identification of detector anomalies beyond current models

Abstract

We demonstrate a direct single-source measurement of absolute nonlinearity of single-photon detectors with unprecedented accuracy. We discover a surprising supralinear behavior of single-photon avalanche diodes and show that it cannot be explained using known theoretical models. We also fully characterize sub- and supra-linear operation regimes of superconducting nanowire single-photon detectors and uncover the supralinearity under faint continuous illumination. The results identify new detector anomalies that supersede existing knowledge of nonlinear effects at the single-photon level.