Improved finite-size key rates for discrete-modulated continuous variable quantum key distribution under coherent attacks

Abstract

Continuous variable quantum key distribution (CVQKD) with discrete modulation combines advantages of CVQKD, such as the implementability using readily available technologies, with advantages of discrete variable quantum key distribution, such as easier error correction procedures. We consider a prepare-and-measure CVQKD protocol, where Alice chooses from a set of four coherent states and Bob performs a heterodyne measurement, the result of which is discretised in both key and test rounds. We provide a security proof against coherent attacks in the finite-size regime, and compute the achievable key rate. To this end, we employ the generalised entropy accumulation theorem, as well as recent advances in conic optimisation, yielding improved key rates compared to previous works. At metropolitan distances, our method can provide positive key rates for the order of $10^8$ rounds.

24 pages, 5 figures

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Cited by in corpus (7)

• Continuous-variable quantum communication
• Experimental composable key distribution using discrete-modulated continuous variable quantum cryptography
• Quantum key distribution rates from non-symmetric conic optimization
• An introductory review of the theory of continuous-variable quantum key distribution: Fundamentals, protocols, and security
• Quantum Key Distribution with Imperfections: Recent Advances in Security Proofs
• Finite-size secret-key rates of discrete modulation continuous-variable quantum key distribution under Gaussian attacks
• Finite-size security of QKD: comparison of three proof techniques