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） 系统发展到开发旨在最大限度地提高网络容量的固有多用户协议。在这里，我们提出了一种基于连续变量 （CV） 系统的量子无源光网络 （QPON） 协议，特别是相干态的正交，它可以在所有网络用户之间实现确定性、同步和高速的密钥生成。我们实现了两种协议，为网络用户分配了不同的信任级别，并在具有 8 个用户的量子访问网络中实验演示了密钥生成，每个用户都有 11 公里的访问链路跨度。根据对用户的信任假设，我们达到 1.5 和 2.1 Mbits/s 的总网络密钥生成量（或有限大小的通道估计为 0.4 和 1.0 Mbits/s）。我们的 CV-QPON 协议展示了扩展网络容量以高速容纳数十个用户的潜力，为建立低成本、高速率和可扩展的安全量子接入网络开辟了新的可能性，作为通往量子互联网的垫脚石。