10~Mb/s quantum key distribution

TL;DR

This paper presents the development of high-speed quantum key distribution systems capable of generating secure keys exceeding 10 Mb/s, demonstrating robustness, stability, and advanced post-processing techniques for practical quantum communication.

Contribution

The authors introduce a novel high-speed QKD system with optimized hardware and protocols achieving record secure key rates over 10 Mb/s and long-term stability without user intervention.

Findings

Achieved secure key rates over 13.7 Mb/s over a 2 dB channel.

Demonstrated continuous operation for over a month with stable performance.

Implemented efficient decoy-state BB84 protocol with large dataset for security.

Abstract

We report the first quantum key distribution (QKD) systems capable of delivering sustainable, real-time secure keys continuously at rates exceeding 10 Mb/s. To achieve such rates, we developed high speed post-processing modules, achieving maximum data throughputs of 60 MC/s, 55 Mb/s, and 108 Mb/s for standalone operation of sifting, error correction and privacy amplification modules, respectively. The photonic layer of the QKD systems features high-speed single photon detectors based on self-differencing InGaAs avalanche photodiodes, phase encoding using asymmetric Mach-Zehnder interferometer, and active stabilization of the interferometer phase and photon polarisation. An efficient variant of the decoy-state BB84 protocol is implemented for security analysis, with a large dataset size of $10^8$ bits selected to mitigate finite-size effects. Over a 2 dB channel, a record secure key rate of 13.72 Mb/s has been achieved averaged over 4.4 days of operation. We confirm the robustness and long-term stability on a second QKD system continuously running for 1 month without any user intervention.