Boosting the secret key rate in a shared quantum and classical fibre communication system

TL;DR

This paper demonstrates a high-rate quantum key distribution system using a 37-core fiber, achieving a combined secret key rate of over 105 Mbps while co-propagating classical signals, advancing secure quantum communications.

Contribution

It introduces a multi-core fiber approach to significantly boost quantum key distribution rates and integrates classical signals, enabling shared quantum-classical communication networks.

Findings

Achieved a secret key rate of 105.7 Mbit/s using multi-core fiber.

Successfully co-propagated classical signals at 370 Gbit/s with quantum signals.

Demonstrated robustness of the system with off-the-shelf equipment.

Abstract

During the last 20 years, the advance of communication technologies has generated multiple exciting applications. However, classical cryptography, commonly adopted to secure current communication systems, can be jeopardized by the advent of quantum computers. Quantum key distribution (QKD) is a promising technology aiming to solve such a security problem. Unfortunately, current implementations of QKD systems show relatively low key rates, demand low channel noise and use ad hoc devices. In this work, we picture how to overcome the rate limitation by using a 37-core fibre to generate 2.86 Mbit/s per core that can be space multiplexed into the highest secret key rate of 105.7 Mbit/s to date. We also demonstrate, with off-the-shelf equipment, the robustness of the system by co-propagating a classical signal at 370 Gbit/s, paving the way for a shared quantum and classical communication network.