Efficient source-independent quantum conference key agreement

TL;DR

This paper introduces a source-independent quantum conference key agreement protocol that significantly improves key rates and scalability over previous entanglement-based methods, with promising applications in quantum networks.

Contribution

The authors propose a novel source-independent QCKA scheme using post-matching, providing unconditional security and enhanced key rates compared to prior entanglement protocols.

Findings

Key rate improved from $O(\eta^{n})$ to $O(\eta^{2})$

Simulation shows orders of magnitude performance gains over long distances

Protocol feasible within existing entangled photon networks

Abstract

Quantum conference key agreement (QCKA) enables the unconditional secure distribution of conference keys among multiple participants. Due to challenges in high-fidelity preparation and long-distance distribution of multi-photon entanglement, entanglement-based QCKA is facing severe limitations in both key rate and scalability. Here, we propose a source-independent QCKA scheme utilizing the post-matching method, feasible within the entangled photon pair distribution network. We introduce an equivalent distributing virtual multi-photon entanglement protocol for providing the unconditional security proof even in the case of coherent attacks. For the symmetry star-network, comparing with previous $n$-photon entanglement protocol, the conference key rate is improved from $O(\eta^{n})$ to $O(\eta^{2})$, where $\eta$ is the transmittance from the entanglement source to one participant. Simulation results show that the performance of our protocol has multiple orders of magnitude advantages in the intercity distance. We anticipate that our approach will demonstrate its potential in the implementation of quantum networks.