Origin of intrinsic dark count in superconducting nanowire single-photon detectors

TL;DR

This study investigates the fundamental cause of dark counts in superconducting nanowire single-photon detectors, identifying vortex-antivortex unbinding as the primary mechanism through experimental and theoretical analysis.

Contribution

It provides new insights into the microscopic origin of dark counts, linking them to vortex dynamics and thermal fluctuations in superconducting nanowires.

Findings

Dark count rate depends on bias current and temperature.

Vortex-antivortex unbinding explains the dark count mechanism.

Thermal fluctuations influence vortex behavior.

Abstract

The origin of the decoherence in superconducting nanowire single-photon detectors, the so-called dark count, was investigated. We measured the direct-current characteristics and bias-current dependencies of the dark count rate in a wide range of temperatures from 0.5 K to 4 K, and analyzed the results by theoretical models of thermal fluctuations of vortices. Our results indicate that the current-assisted unbinding of vortex-antivortex pairs is the dominant origin of the dark count.