Robustness of entanglement-based discrete- and continuous-variable quantum key distribution against channel noise

TL;DR

This paper compares the robustness of entanglement-based discrete-variable and continuous-variable quantum key distribution protocols against channel noise, demonstrating the practical superiority of DV schemes under realistic conditions.

Contribution

It provides a comprehensive analysis and fundamental bounds on noise tolerance, highlighting the realistic advantages of DV over CV QKD protocols.

Findings

DV protocols are more resistant to channel noise than CV protocols.

Fundamental bounds on noise tolerance for CV QKD are derived.

Realistic DV setups can outperform ideal CV protocols with proper parameters.

Abstract

Discrete-variable (DV) and continuous-variable (CV) schemes constitute the two major families of quantum key distribution (QKD) protocols. Unfortunately, since the setup elements required by these schemes are quite different, making a fair comparison of their potential performance in particular applications is often troublesome, limiting the experimenters' capability to choose an optimal solution. In this work we perform a general comparison of the major entanglement-based DV and CV QKD protocols in terms of their resistance to the channel noise, with the otherwise perfect setup, showing the definite superiority of the DV family. We analytically derive fundamental bounds on the tolerable channel noise and attenuation for entanglement-based CV QKD protocols. We also investigate the influence of DV QKD setup imperfections on the obtained results in order to determine benchmarks for the parameters of realistic photon sources and detectors, allowing the realistic DV protocols to outperform even the ideal CV QKD analogs. Our results indicate the realistic advantage of DV entanglement-based schemes over their CV counterparts and suggests the practical efforts for maximizing this advantage.