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arXiv · 2211.15559

Overcoming fundamental bounds on quantum conference key agreement

Giacomo Carrara·Gláucia Murta·Federico Grasselli
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Abstract

Twin-Field Quantum Key Distribution (TF-QKD) enables two distant parties to establish a shared secret key, by interfering weak coherent pulses (WCPs) in an intermediate measuring station. This allows TF-QKD to reach greater distances than traditional QKD schemes and makes it the only scheme capable of beating the repeaterless bound on the bipartite private capacity. Here, we generalize TF-QKD to the multipartite scenario. Specifically, we propose a practical conference key agreement (CKA) protocol that only uses WCPs and linear optics and prove its security with a multiparty decoy-state method. Our protocol allows an arbitrary number of parties to establish a secret conference key by single-photon interference, enabling it to overcome recent bounds on the rate at which conference keys can be established in quantum networks without a repeater.

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Giacomo Carrara, Gláucia Murta, Federico Grasselli. 2022-11-28. Overcoming fundamental bounds on quantum conference key agreement. https://doi.org/10.1103/physrevapplied.19.064017

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