  Optical access networks connect multiple endpoints to a common network node
via shared fibre infrastructure. They will play a vital role to scale up the
number of users in quantum key distribution (QKD) networks. However, the
presence of power splitters in the commonly used passive network architecture
makes successful transmission of weak quantum signals challenging. This is
especially true if QKD and data signals are multiplexed in the passive network.
The splitter introduces an imbalance between quantum signal and Raman noise,
which can prevent the recovery of the quantum signal completely. Here we
introduce a method to overcome this limitation and demonstrate coexistence of
multi-user QKD and full power data traffic from a gigabit passive optical
network (GPON). The dual feeder implementation is compatible with standard GPON
architectures and can support up to 128 users, highlighting that quantum
protected GPON networks could be commonplace in the future.
