Low-Dimensional Reconciliation for Continuous-Variable Quantum Key Distribution

TL;DR

This paper introduces a low-dimensional reconciliation method for CVQKD that improves key rates and distances by correcting quantum channel noise at the raw-data level in scalar space, enabling practical and secure quantum communication.

Contribution

It presents a novel low-dimensional reconciliation technique operating on raw data, enhancing CVQKD performance and security over existing methods.

Findings

Error probability of 1D reconciliation is zero in practical scenarios.

Method significantly improves key rates and transmission distances.

Reconciliation can be extended to arbitrary dimensions.

Abstract

We propose an efficient logical layer-based reconciliation method for continuous-variable quantum key distribution (CVQKD) to extract binary information from correlated Gaussian variables. We demonstrate that by operating on the raw-data level, the noise of the quantum channel can be corrected in the low-dimensional (scalar) space and the reconciliation can be extended to arbitrary dimensions. The CVQKD systems allow an unconditionally secret communication over standard telecommunication networks. To exploit the real potential of CVQKD a robust reconciliation technique is needed. It is currently unavailable, which makes it impossible to reach the real performance of the CVQKD protocols. The reconciliation is a post-processing step separated from the transmission of quantum states, which is aimed to derive the secret key from the raw data. The reconciliation process of correlated Gaussian variables is a complex problem that requires either tomography in the physical layer that is intractable in a practical scenario, or high-cost calculations in the multidimensional spherical space with strict dimensional limitations. To avoid these issues we define the low-dimensional reconciliation. We prove that the error probability of one-dimensional reconciliation is zero in any practical CVQKD scenario, and provides unconditional security. The results allow to significantly improve the currently available key rates and transmission distances of CVQKD.