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arXiv · 2101.05799

Dimension Reduction in Quantum Key Distribution for Continuous- and Discrete-Variable Protocols

Twesh Upadhyaya·Thomas van Himbeeck·Jie Lin·Norbert Lütkenhaus
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Abstract

We develop a method to connect the infinite-dimensional description of optical continuous-variable quantum key distribution (QKD) protocols to a finite-dimensional formulation. The secure key rates of the optical QKD protocols can then be evaluated using recently-developed reliable numerical methods for key rate calculations. We apply this method to obtain asymptotic key rates for discrete-modulated continuous-variable QKD protocols, which are of practical significance due to their experimental simplicity and potential for large-scale deployment in quantum-secured networks. Importantly, our security proof does not require the photon-number cutoff assumption relied upon in previous works. We also demonstrate that our method can provide practical advantages over the flag-state squasher when applied to discrete-variable protocols.

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Twesh Upadhyaya, Thomas van Himbeeck, Jie Lin, Norbert Lütkenhaus. 2021-01-14. Dimension Reduction in Quantum Key Distribution for Continuous- and Discrete-Variable Protocols. https://doi.org/10.1103/prxquantum.2.020325

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