Coexistence of high-bit-rate quantum key distribution and data on optical fiber

TL;DR

This paper demonstrates a method for simultaneous high-bit-rate quantum key distribution and classical data transmission over a single optical fiber up to 90 km, using a novel temporal-filtering technique to reject noise photons.

Contribution

It introduces a new temporal-filtering effect that significantly improves noise rejection, enabling secure QKD alongside high-speed data over existing fiber infrastructure.

Findings

QKD achieved over 90 km fiber with Gb/s data rates

Noise-photon contamination effectively suppressed

Potential for integration into existing communication networks

Abstract

Quantum key distribution (QKD) uniquely allows distribution of cryptographic keys with security verified by quantum mechanical limits. Both protocol execution and subsequent applications require the assistance of classical data communication channels. While using separate fibers is one option, it is economically more viable if data and quantum signals are simultaneously transmitted through a single fiber. However, noise-photon contamination arising from the intense data signal has severely restricted both the QKD distances and secure key rates. Here, we exploit a novel temporal-filtering effect for noise-photon rejection. This allows high-bit-rate QKD over fibers up to 90 km in length and populated with error-free bidirectional Gb/s data communications. With high-bit rate and range sufficient for important information infrastructures, such as smart cities and 10 Gbit Ethernet, QKD is a significant step closer towards wide-scale deployment in fiber networks.