Long-distance continuous-variable quantum key distribution with efficient channel estimation

TL;DR

This paper introduces a double-modulation protocol for continuous-variable quantum key distribution that enhances long-distance performance and key rates by optimizing resource use and channel estimation techniques.

Contribution

The paper proposes a novel double-modulation protocol that improves long-distance quantum key distribution by optimizing parameters and combining squeezed and coherent states.

Findings

Key rate approaches theoretical limit for long distances

Achieves ten times higher key rate with ten times shorter block size

Enhances channel estimation efficiency in finite-size settings

Abstract

We investigate the main limitations which prevent the continuous-variable quantum key distribution protocols from achieving long distances in the finite-size setting. We propose a double-modulation protocol which allows using each state for both channel estimation and key distribution. As opposed to the standard method, we optimize the parameters of the protocol and consider squeezed as well as coherent states as a signal. By optimally combining the resources the key rate can approach the theoretical limit for long distances, and one can obtain about ten times higher key rate using ten times shorter block size than in the current state-of-the-art implementation.