Tantalum nitride superconducting single-photon detectors with low cut-off energy

TL;DR

This paper reports the development of tantalum nitride superconducting single-photon detectors with a lower energy gap, enabling detection of lower-energy photons more efficiently, aligning with theoretical models.

Contribution

The study introduces a TaN detector with a smaller superconducting gap and lower density of states, improving low-energy photon detection compared to NbN devices.

Findings

Reduced minimum photon energy for detection by approximately one-third.

TaN detector exhibits a smaller superconducting energy gap.

Detection efficiency for low-energy photons is enhanced.

Abstract

Materials with a small superconducting energy gap are expected to favor a high detection efficiency of low-energy photons in superconducting nanowire single-photon detectors. We developed a TaN detector with smaller gap and lower density of states at the Fermi energy than in comparable NbN devices, while other relevant parameters remain essentially unchanged. The observed reduction of the minimum photon energy required for direct detection is in line with model predictions of $\approx1/3$ as compared to NbN.