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Characterization of State-Preparation Uncertainty in Quantum Key Distribution

The authors investigate how to create a secure quantum key distribution (QKD) by performing a proof-of-principle demonstration of the experimental techniques for characterizing the source phase and intensity fluctuation in commercial QKD systems.

Publication Date: January 18, 2023

Authors: Anqi Huang, Akihiro Mizutani, Hoi-Kwong Lo (CQIQC Member), Vadim Makarov, and Kiyoshi Tamaki


We propose a fully passive linear optical quantum key distribution (QKD) source that implements both random decoy-state and encoding choices with postselection only, thus eliminating all side channels in active modulators. Our source is general purpose and can be used in, e.g., BB84, the six-state protocol, and reference-frame-independent QKD. It can even potentially be combined with measurement-device- independent QKD to achieve robustness against side channels in both detectors and modulators. We also perform a proof-of-principle experimental source characterization to show its feasibility.

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