Upper Bounds on Device-Independent Quantum Key Distribution

Matthias Christandl, Roberto Ferrara, Karol Horodecki

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Abstract

Quantum key distribution (QKD) is a method that distributes a secret key to a sender and a receiver by the transmission of quantum particles (e.g., photons). Device-independent quantum key distribution (DIQKD) is a version of QKD with a stronger notion of security, in that the sender and receiver base their protocol only on the statistics of input and outputs of their devices as inspired by Bell’s theorem. We study the rate at which DIQKD can be carried out for a given bipartite quantum state distributed between the sender and receiver or a quantum channel connecting them. We provide upper bounds on the achievable rate going beyond upper bounds possible for QKD. In particular, we construct states and channels where the QKD rate is significant while the DIQKD rate is negligible. This gap is illustrated for a practical case arising when using standard postprocessing techniques for entangled two-qubit states.
Original languageEnglish
Article number160501
JournalPhysical Review Letters
Volume126
Issue number16
Number of pages6
ISSN0031-9007
DOIs
Publication statusPublished - 2021

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