Work

The security of practical post-selection in Gaussian-modulated continuous-variable quantum key distribution

Year: 2026

Type: article

Abstract: Gaussian-modulated coherent-state (GMCS) continuous-variable quantum key distribution (CV-QKD) offers a practical path to quantum-secured communication owing to its compatibility with existing optical fibre networks and use of mature security proofs. Achieving high secret key rates in real-time systems, however, requires post-processing schemes that are both information-theoretically efficient and computationally scalable. In previous experimental work 1 , we have demonstrated record real-time key rates using a one-round sliced reconciliation scheme with guard-band post-selection. Here, we present the corresponding theoretical framework and provide an asymptotic security analysis that considers arbitrary collective attacks, a much broader class of attacks than the usually assumed Gaussian collective attacks. The security analysis applies the entropic continuity of quantum channels justified by a quantum channel estimation procedure. In conditions of high noise, our scheme uses 500 times less classical communication than multidimensional reconciliation.

Source: npj Quantum Information

DOI: 10.1038/s41534-026-01366-0

Authors: Adam Alderton, Amanda Weerasinghe, Muataz Alhussein, Adrian Wonfor, Richard Penty

Institution: University of Cambridge

Language: English

Topic: Quantum Information and Cryptography

Subfield: Artificial Intelligence

Field: Computer Science

Domain: Physical Sciences

Open Access status: gold

Estimated APC paid: $4,290

Funder: Engineering and Physical Sciences Research Council