Practical continuous-variable quantum key distribution with squeezed light

TL;DR

This paper experimentally demonstrates a practical squeezed-state CV-QKD system that offers higher secret key rates and better noise resilience compared to traditional coherent-state systems, advancing quantum communication technology.

Contribution

It introduces a practical implementation of squeezed-state CV-QKD with modern techniques, verifying theoretical advantages over coherent states in real fiber channels.

Findings

Squeezed-state CV-QKD achieves higher secret key rates.

The system shows increased resilience to excess noise.

Finite-size security against collective attacks is maintained.

Abstract

Continuous-variable quantum key distribution (CV-QKD) has gathered significant interest for its potential to achieve high secret key rates and seamless integration with existing optical communication infrastructure. State-of-the-art CV-QKD systems primarily use coherent states for simplicity. However, squeezed states of light have been theoretically shown to offer significant advantages, including higher secret key rates, greater resilience to excess noise, and reduced requirements on information reconciliation efficiency. In this work, we experimentally verify these theoretical predictions and propose and demonstrate a practical squeezed-state CV-QKD system based on modern local-local oscillator and digital-signal-processing techniques. Operating over fibre channels and considering finite-size security against collective attacks we show the advantages of our system over its coherent state counterpart. Our work paves the way for squeezed states to become practical resources for quantum key distribution and other quantum information protocols.