Characterization of superconducting nanowire single-photon detector with artificial constrictions

TL;DR

This study investigates how artificial constrictions in superconducting nanowire single-photon detectors affect their performance, revealing that dark counts originate from constrictions and confirming their impact on detection efficiency.

Contribution

The paper introduces a method to fabricate artificial constrictions in SNSPDs and systematically studies their influence on detector performance, providing direct evidence of constrictions' effects.

Findings

Dark counts originate from a single constriction.

Artificial constrictions affect detection efficiency.

Constrictions influence kinetic inductance and bias current relationship.

Abstract

Statistical studies on the performance of different superconducting nanowire single-photon detectors (SNSPDs) on one chip suggested that random constrictions existed in the nanowire that were barely registered by scanning electron microscopy. With the aid of advanced e-beam lithography, artificial geometric constrictions were fabricated on SNSPDs as well as single nanowires. In this way, we studied the influence of artificial constrictions on SNSPDs in a straight forward manner. By introducing artificial constrictions with different wire widths in single nanowires, we concluded that the dark counts of SNSPDs originate from a single constriction. Further introducing artificial constrictions in SNSPDs, we studied the relationship between detection efficiency and kinetic inductance and the bias current, confirming the hypothesis that constrictions exist in SNSPDs.