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arXiv · 2105.06748

Gigahertz measurement-device-independent quantum key distribution using directly modulated lasers

R. I. Woodward·Y. S. Lo·M. Pittaluga·M. Minder·T. K. Paraïso·M. Lucamarini·Z. L. Yuan·A. J. Shields
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Abstract

Measurement-device-independent quantum key distribution (MDI-QKD) is a technique for quantum-secured communication that eliminates all detector side-channels, although is currently limited by implementation complexity and low secure key rates. Here, we introduce a simple and compact MDI-QKD system design at gigahertz clock rates with enhanced resilience to laser fluctuations - thus enabling free-running semiconductor laser sources to be employed without spectral or phase feedback. This is achieved using direct laser modulation, carefully exploiting gain-switching and injection-locking laser dynamics to encode phase-modulated time-bin bits. Our design enables secure key rates that improve upon the state of the art by an order of magnitude, up to 8 bps at 54 dB channel loss and 2 kbps in the finite-size regime for 30 dB channel loss. This greatly simplified MDI-QKD system design and proof-of-principle demonstration shows that MDI-QKD is a practical, high-performance solution for future quantum communication networks.

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R. I. Woodward, Y. S. Lo, M. Pittaluga, M. Minder, T. K. Paraïso, M. Lucamarini, Z. L. Yuan, A. J. Shields. 2021-05-14. Gigahertz measurement-device-independent quantum key distribution using directly modulated lasers. https://doi.org/10.1038/s41534-021-00394-2

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