Multipartite entanglement enables secure and anonymous key exchange between multiple parties in a network. In particular Greenberger-Horne-Zeilinger (GHZ) states have been introduced as resource states for anonymous key exchange protocols, in which an anonymous subset of parties within a larger network establishes a secret key. However, the use of other types of multipartite entanglement for such protocols remains relatively unexplored. Here we demonstrate that linear cluster states can serve as a versatile and potentially scalable resource in such applications. We implemented an anonymous key exchange protocol with four photons in a linear cluster state and established a shared key between three parties in our network. We show how to optimize the protocol parameters to account for noise and to maximize the finite key rate under realistic conditions. As cluster states have been established as a flexible resource in quantum computation, we expect that our demonstration provides a first step towards their hybrid use for networked computing and communication.
Comment on "Fully device-independent conference key agreement" [Phys. Rev. A 97, 022307 (2018)]
在本文中，我们讨论了设备无关会议密钥协商（DICKA）协议[Phys. Rev. A 97，022307（2018）]。我们表明，建议诚实的实施失败，因为完美的相关测量结果和所需的贝尔不等式违反不能同时实现，在矛盾的声称。我们进一步表明，通过半定规划，不可能存在任何合适的诚实的实现三方设置，使DICKA协议不完整。
Strategy optimization for quantum conference key agreement in asymmetric star networks
Technische Universität Berlin（柏林工业大学）；Heinrich Heine University Düsseldorf（杜塞尔多夫大学）；Freie Universität Berlin（柏林自由大学）；Helmholtz-Zentrum Berlin für Materialien und Energie（亥姆霍兹柏林材料与能源中心）；Universität Innsbruck（因斯布鲁克大学）
National Laboratory of Solid State Microstructures and School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University（南京大学固体微结构物理国家重点实验室、物理学院、先进微结构协同创新中心）；School of Physics and Key Laboratory of Quantum State Construction and Manipulation (Ministry of Education), Renmin University of China（中国人民大学物理学院、量子态构建与操控教育部重点实验室）；Beijing Academy of Quantum Information Sciences（北京量子信息科学研究院）；Yunnan Key Laboratory for Quantum Information, Yunnan University（云南大学云南省量子信息重点实验室）
Improving the Loss Tolerance of Heralded Photonic GHZ States for Long-Distance Device-Independent Conference Key Agreement
Imperial College London（帝国理工学院）；Keio University（庆应义塾大学）；Curtin University（科廷大学）；University of Oxford（牛津大学）；National Institute of Information and Communications Technology (NICT)（信息通信研究机构）
Performance Analysis of Multiparty GHZ-State Quantum Conference Key Agreement over Optical Fiber Channel
Indian Institute of Technology Delhi（印度德里理工学院）；Centre for Applied Research in Electronics (CARE)（电子应用研究中心）；Bharti School of Telecommunication Technology and Management（Bharti电信技术与管理学院）；University of Melbourne（墨尔本大学）
Pauli Error Composition Determines the Multipartite Advantage in Conference Key Agreement
The Coding School dba Frontier Technology Institute（Frontier Technology Institute）；Department of Computer Science, University of Maryland, College Park, Maryland, USA（马里兰大学）
该研究通过精确模拟不同噪声下的 GHZ 会议密钥协商协议，发现 Pauli 错误组成决定其相对 BB84 的多体优势，并推导闭式速率证明噪声分散优于集中。
Security of passive entanglement-based key distribution protocols
Network Innovation Laboratories, NTT, Inc.（NTT网络创新实验室）；NTT Research Center for Theoretical Quantum Information, NTT, Inc.（NTT理论量子信息研究中心）；Basic Research Laboratories, NTT, Inc.（NTT基础研究所）
