Secret key rate bounds for quantum key distribution with non-uniform phase randomization

Abstract

Decoy-state quantum key distribution (QKD) is undoubtedly the most efficient solution to handle multi-photon signals emitted by laser sources, and provides the same secret key rate scaling as ideal single-photon sources. It requires, however, that the phase of each emitted pulse is uniformly random. This might be difficult to guarantee in practice, due to inevitable device imperfections and/or the use of an external phase modulator for phase randomization, which limits the possible selected phases to a finite set. Here, we investigate the security of decoy-state QKD with arbitrary, continuous or discrete, non-uniform phase randomization, and show that this technique is quite robust to deviations from the ideal uniformly random scenario. For this, we combine a novel parameter estimation technique based on semi-definite programming, with the use of basis mismatched events, to tightly estimate the parameters that determine the achievable secret key rate. In doing so, we demonstrate that our analysis can significantly outperform previous results that address more restricted scenarios.

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Cited by in corpus (5)

• Security framework for quantum key distribution with imperfect sources
• Quantum key distribution with imperfectly isolated devices
• Characterising higher-order phase correlations in gain-switched laser sources with application to quantum key distribution
• A consolidated and accessible security proof for finite-size decoy-state quantum key distribution
• Evaluation of quantum key distribution systems against injection-locking attacks