Adaptable Continuous Variable Quantum Network with Finite Size Security

TL;DR

This paper demonstrates an active multi-user continuous-variable quantum network with finite-size security, achieving high secret key rates over 11 km channels, and explores adaptable protocols for diverse security needs.

Contribution

It presents the first experimental multi-user CV quantum network with finite-size security and adaptable protocols for different security and key rate requirements.

Findings

Achieved secret key generation of 0.19 bits per channel use.

Exchanged 1.25 billion coherent states over 11 km channels.

Established practical security compatible with existing telecommunication infrastructure.

Abstract

In recent years, continuous-variable quantum key distribution (CV-QKD) has become a promising paradigm for enabling secure communication among multiple end users sharing the same telecommunication backbone. CV-QKD with reverse reconciliation naturally enables scalability from conventional point-to-point links to quantum access networks based on passive quantum broadcasting channels. Here, we report an experimental demonstration on an active $1:4$ multi-user CV quantum network (QN) in the finite-size regime. With $1.25\cdot10^9$ coherent states exchanged on each $11\text{km}$ quantum channel, the highest performance for secret key generation totaling $1.9\cdot10^{-1}$ bits/channel use. Furthermore, we investigate adaptable CV-QN protocols that comprehensively allow network operation in various security and key rates requirements of individual users. The results establish the practical security of CV-QN compatible with existing telecommunication for broad deployment, and allowing additional degree of freedom for connected end users in existing infrastructures.