A low-noise single-photon detector for long-distance free-space quantum communication

TL;DR

This paper presents a highly sensitive, low-noise single-photon detector optimized for long-distance free-space quantum communication, featuring low dark counts, high efficiency, and minimal afterpulsing.

Contribution

It introduces a novel low-noise single-photon detector with detailed characterization and an improved long-time afterpulsing analysis method for quantum communication applications.

Findings

Dark count rate below 1 Hz

Photon detection efficiency around 50%

Timing jitter under 1 ns

Abstract

We build and test a single-photon detector based on a Si avalanche photodiode Excelitas 30902SH thermoelectrically cooled to -100 deg. C. Our detector has dark count rate below 1 Hz, 500 um diameter photosensitive area, photon detection efficiency around 50%, afterpulsing less than 0.35%, and timing jitter under 1 ns. These characteristics make it suitable for long-distance free-space quantum communication links, which we briefly discuss. We also report an improved method that we call long-time afterpulsing analysis, used to determine and visualise long trap lifetimes at different temperatures.