Single-photon detection using large-scale high-temperature MgB$_2$ sensors at 20 K

TL;DR

This paper demonstrates MgB$_2$ superconducting microwires capable of single-photon detection at 20 K, offering high efficiency, fast reset times, and broad temperature operation, advancing applications in quantum communication and space technologies.

Contribution

It introduces MgB$_2$ thin-film microwires as high-temperature single-photon detectors with enhanced performance and operational temperature range, surpassing previous superconducting detector limits.

Findings

Single-photon sensitivity up to 20 K

Detection efficiency saturation at 3.7 K for 1 μm wires

Reset time as low as 1 ns despite large active area

Abstract

Ultra-fast single-photon detectors with high current density and operating temperature can benefit space and ground applications, including quantum optical communication systems, lightweight cryogenics for space crafts, and medical use. Here we demonstrate magnesium diboride (MgB$_2$) thin-film superconducting microwires capable of single-photon detection at 1.55 $\mu$m optical wavelength. We used helium ions to alter the properties of MgB$_2$, resulting in microwire-based detectors exhibiting single-photon sensitivity across a broad temperature range of up to 20 K, and detection efficiency saturation for 1 $\mu$m wide microwires at 3.7 K. Linearity of detection rate vs incident power was preserved up to at least ~100 Mcps. Despite the large active area of up to 400$\times$400 $\mu$m$^2$, the reset time was found to be as low as $\sim1$ ns. Our research provides new possibilities for breaking the operating temperature limit and maximum single-pixel count rate, expanding the detector area, and raises inquiries about the fundamental mechanisms of single-photon detection in high-critical-temperature superconductors.