Characterising higher-order phase correlations in gain-switched laser sources with application to quantum key distribution

• URL: http://arxiv.org/abs/2412.03738v1
• Date: Wed, 04 Dec 2024 22:06:13 GMT
• Title: Characterising higher-order phase correlations in gain-switched laser sources with application to quantum key distribution
• Authors: Alessandro Marcomini, Guillermo Currás-Lorenzo, Davide Rusca, Angel Valle, Kiyoshi Tamaki, Marcos Curty,
• Abstract summary: Multi-photon emissions in laser sources represent a serious threat for the security of quantum key distribution. We introduce experimental schemes to characterise the phase probability distribution of the emitted pulses. We demonstrate that an optimisation task over interferometric measures suffices in determining the impact of arbitrary order correlations.
• Score: 38.00713966087315
• License:
• Abstract: Multi-photon emissions in laser sources represent a serious threat for the security of quantum key distribution (QKD). While the decoy-state technique allows to solve this problem, it requires uniform phase randomisation of the emitted pulses. However, gain-switched lasers operating at high repetition rates do not fully satisfy this requirement, as residual photons in the laser cavity introduce correlations between the phases of consecutive pulses. Here, we introduce experimental schemes to characterise the phase probability distribution of the emitted pulses, and demonstrate that an optimisation task over interferometric measures suffices in determining the impact of arbitrary order correlations, which ultimately establishes the security level of the implementation according to recent security proofs. We expect that our findings may find usages beyond QKD as well.

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