Improvement of two-way continuous-variable quantum key distribution with virtual photon subtraction

TL;DR

This paper introduces a virtual photon subtraction method to enhance two-way continuous-variable quantum key distribution, improving transmission distance, noise tolerance, and robustness through non-Gaussian post-selection.

Contribution

The paper presents a novel virtual photon subtraction technique applied to two-way CV-QKD, demonstrating improved performance and robustness over existing protocols.

Findings

Enhanced entanglement via virtual photon subtraction

Increased transmission distance and noise tolerance

Robustness maintained at longer distances

Abstract

We propose a method to improve the performance of two-way continuous-variable quantum key distribution protocol by virtual photon subtraction. The Virtual photon subtraction implemented via non-Gaussian post-selection not only enhances the entanglement of two-mode squeezed vacuum state but also has advantages in simplifying physical operation and promoting efficiency. In two-way protocol, virtual photon subtraction could be applied on two sources independently. Numerical simulations show that the optimal performance of renovated two-way protocol is obtained with photon subtraction only used by Alice. The transmission distance and tolerable excess noise are improved by using the virtual photon subtraction with appropriate parameters. Moreover, the tolerable excess noise maintains a high value with the increase of distance so that the robustness of two-way continuous-variable quantum key distribution system is significantly improved, especially at long transmission distance.