Quantum key distribution with non-ideal heterodyne detection: composable security of discrete-modulation continuous-variable protocols

Abstract

Continuous-variable quantum key distribution exploits coherent measurements of the electromagnetic field, i.e., homodyne or heterodyne detection. The most advanced security proofs developed so far relied on idealised mathematical models for such measurements, which assume that the measurement outcomes are continuous and unbounded variables. As physical measurement devices have finite range and precision, these mathematical models only serve as an approximation. It is expected that, under suitable conditions, the predictions obtained using these simplified models are in good agreement with the actual experimental implementations. However, a quantitative analysis of the error introduced by this approximation, and of its impact on composable security, have been lacking so far. Here we present a theory to rigorously account for the experimental limitations of realistic heterodyne detection. We focus on collective attacks, and present security proofs for the asymptotic and finite-size regimes, the latter within the framework of composable security. In doing this, we establish for the first time the composable security of discrete-modulation continuous-variable quantum key distribution in the finite-size regime. Tight bounds on the key rates are obtained through semi-definite programming and do not rely on a truncation of the Hilbert space.

v3: close to published version

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• Finite-Size Security for Discrete-Modulated Continuous-Variable Quantum Key Distribution Protocols
• Experimental demonstration of Continuous-Variable Quantum Key Distribution with a silicon photonics integrated receiver
• Security of discrete-modulated continuous-variable quantum key distribution
• Continuous-variable quantum communication
• Optimizing state-discrimination receivers for continuous-variable quantum key distribution over a wiretap channel
• Experimental composable key distribution using discrete-modulated continuous variable quantum cryptography
• Improved finite-size key rates for discrete-modulated continuous variable quantum key distribution under coherent attacks
• Refined finite-size analysis of binary-modulation continuous-variable quantum key distribution
• Analyzing the performance of CV-MDI QKD under continuous-mode scenarios
• Quantum communications in continuous variable systems
• Finite-size secret-key rates of discrete modulation continuous-variable quantum key distribution under Gaussian attacks
• Asymmetry effects in homodyne and heterodyne measurements: Positive operator-valued measures and asymptotic security of Gaussian-continuous-variable quantum key distribution
• Finite-size security of QKD: comparison of three proof techniques