Hajomer Adnan A E, Derkach Ivan, Filip Radim, Andersen Ulrik L, C Usenko Vladyslav, Gehring Tobias
Center for Macroscopic Quantum States (bigQ), Department of Physics, Technical University of Denmark, 2800, Kongens Lyngby, Denmark.
Department of Optics, Faculty of Science, Palacky University, 17. listopadu 12, 771 46, Olomouc, Czech Republic.
Light Sci Appl. 2024 Oct 16;13(1):291. doi: 10.1038/s41377-024-01633-9.
To establish a scalable and secure quantum network, a critical milestone is advancing from basic point-to-point quantum key distribution (QKD) systems to the development of inherently multi-user protocols designed to maximize network capacity. Here, we propose a quantum passive optical network (QPON) protocol based on continuous-variable (CV) systems, particularly the quadrature of the coherent state, which enables deterministic, simultaneous, and high-rate secret key generation among all network users. We implement two protocols with different trust levels assigned to the network users and experimentally demonstrate key generation in a quantum access network with 8 users, each with an 11 km span of access link. Depending on the trust assumptions about the users, we reach 1.5 and 2.1 Mbits/s of total network key generation (or 0.4 and 1.0 Mbits/s with finite-size channels estimation). Demonstrating the potential to expand the network's capacity to accommodate tens of users at a high rate, our CV-QPON protocols open up new possibilities in establishing low-cost, high-rate, and scalable secure quantum access networks serving as a stepping stone towards a quantum internet.
为了建立一个可扩展且安全的量子网络，一个关键的里程碑是从基本的点对点量子密钥分发（QKD）系统发展到设计用于最大化网络容量的固有多用户协议。在此，我们提出一种基于连续变量（CV）系统的量子无源光网络（QPON）协议，特别是相干态的正交分量，它能够在所有网络用户之间确定性地、同时地且高速率地生成秘密密钥。我们实现了两种为网络用户分配不同信任级别的协议，并在一个具有8个用户的量子接入网络中进行了实验演示，每个用户的接入链路跨度为11公里。根据对用户的信任假设，我们实现了总网络密钥生成速率分别为1.5和2.1兆比特每秒（对于有限尺寸信道估计，分别为0.4和1.0兆比特每秒）。我们的CV - QPON协议展示了扩展网络容量以高速率容纳数十个用户的潜力，为建立低成本、高速率且可扩展的安全量子接入网络开辟了新的可能性，成为通向量子互联网的一块垫脚石。
