High-efficiency single photon detector combined with an ultra-small APD module and a self-training discriminator for high-speed quantum cryptosystems

TL;DR

This paper presents a high-speed, ultra-small single-photon detector with the lowest dark count rate, significantly enhancing quantum key generation rates for quantum cryptography systems.

Contribution

Introduction of a novel, compact SPAD with a 3 GHz bandwidth and self-training discriminator, achieving record-low dark counts and higher quantum key rates.

Findings

Achieved the highest photon detection frequency in a board-mountable system.

Reduced dark count rate to one-tenth of previous detectors.

Enabled a 3.2-fold increase in quantum key generation rate.

Abstract

A single-photon avalanche detector (SPAD) for high-speed quantum-key generation has successfully been developed. It has the highest photon detection repetition frequency and the lowest dark count rate in the world, as a board-mountable sub-system. The SPAD consists of an ultra-small dual-avalanche photodiode (APD) module and a novel discriminator. The APD module design is consistent with cooling capability and high-frequency characteristics. The new module has a 3 GHz bandwidth enabling 1 GHz gate-pulse repetition. The bandwidth is extended 15-fold relative to the most wideband peltier cooled APD module. The discriminator has a self-training mechanism to compensate charge pulse. Dark count rare of the SPAD is reduced 1/10th relative to the lowest dark count single photon detector. The SPAD allows 3.2-fold multiplying the quantum key generation rate in theoretical estimation.