Effective suppression of dark counts in superconducting microstructures with grid of pinholes in a magnetic field

TL;DR

This paper demonstrates that incorporating a pinhole grid in superconducting microwires effectively suppresses dark counts in magnetic fields, enhancing the performance of single-photon detectors by maintaining higher critical currents and reducing noise.

Contribution

The study introduces a novel pinhole grid design in superconducting wires that reduces dark counts and maintains critical current stability in magnetic fields, improving detector reliability.

Findings

Dark counts are significantly suppressed in magnetic fields below 16 mT.

Critical current remains stable or increases in magnetic fields above 10 mT.

Photon detection efficiency remains unaffected by magnetic fields in the tested range.

Abstract

In a magnetic field, vortices significantly contribute to the dark counts of single-photon detectors made of superconducting wires, and they are also limiting the critical current of such devices. To address this issue, we prepared superconducting microwires with a pinhole grid from WSi thin films and report on corresponding critical-current and count-rate measurements in an external magnetic field B. When compared to corresponding devices without pinholes, the critical current only weakly depends on the magnetic field at B < 16 mT and it is even larger already at B > 10 mT. Moreover, dark counts are not only suppressed in zero field, but particularly in magnetic fields B < 16 mT, while photon counts are virtually field insensitive in the same range of the magnetic field.