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.
CITATION STYLE
Upadhyaya, T., Van Himbeeck, T., Lin, J., & Lütkenhaus, N. (2021). Dimension Reduction in Quantum Key Distribution for Continuous- And Discrete-Variable Protocols. PRX Quantum, 2(2). https://doi.org/10.1103/PRXQuantum.2.020325
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