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.
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