Breaking universal limitations on quantum conference key agreement without quantum memory

TL;DR

This paper introduces a measurement-device-independent quantum conference key agreement protocol that significantly improves transmission efficiency and distance without requiring quantum memory, advancing practical quantum networks.

Contribution

It presents a novel protocol leveraging spatial multiplexing and adaptive operations to surpass key rate bounds in lossy channels without quantum memory.

Findings

Enhanced key rate and transmission distance over lossy channels.

Security analysis confirms robustness in the composable framework.

Practical performance demonstrated in finite-size regime.

Abstract

Quantum conference key agreement is an important cryptographic primitive for future quantum network. Realizing this primitive requires high-brightness and robust multiphoton entanglement sources, which is challenging in experiment and unpractical in application because of limited transmission distance caused by channel loss. Here we report a measurement-device-independent quantum conference key agreement protocol with enhanced transmission efficiency over lossy channel. With spatial multiplexing nature and adaptive operation, our protocol can break key rate bounds on quantum communication over quantum network without quantum memory. Compared with previous work, our protocol shows superiority in key rate and transmission distance within the state-of-the-art technology. Furthermore, we analyse the security of our protocol in the composable framework and evaluate its performance in the finite-size regime to show practicality. Based on our results, we anticipate that our protocol will play an indispensable role in constructing multipartite quantum network.