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arXiv · 2210.14296

An Improved Correction Term for Dimension Reduction in Quantum Key Distribution

Twesh Upadhyaya·Thomas van Himbeeck·Norbert Lütkenhaus
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Abstract

The dimension reduction method enables security proofs of quantum key distribution (QKD) protocols that are originally formulated in infinite dimensions via reduction to a tractable finite-dimensional optimization. The reduction of dimensions is associated with a correction term in the secret key rate calculation. The previously derived correction term is loose when the protocol measurements are nearly block-diagonal with respect to the projection onto the reduced finite-dimensional subspace. Here, we provide a tighter correction term. It interpolates between the two extreme cases where all measurement operators are block-diagonal, and where at least one has maximally large off-diagonal blocks. This new correction term can reduce the computational overhead of applying the dimension reduction method by reducing the required dimension of the chosen subspace.

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Twesh Upadhyaya, Thomas van Himbeeck, Norbert Lütkenhaus. 2022-10-25. An Improved Correction Term for Dimension Reduction in Quantum Key Distribution. https://arxiv.org/abs/2210.14296

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