  Quantum networks scale the advantages of quantum communication protocols to
more than just two distant users. Here we present a fully connected quantum
network architecture in which a single entangled photon source distributes
quantum states to a multitude of users. Our network architecture thus minimizes
the resources required of each user without sacrificing security or
functionality. As no adaptations of the source are required to add users, the
network can readily be scaled to a large number of clients, whereby no trust in
the provider of the quantum source is required. Unlike previous attempts at
multi-user networks, which have been based on active components, and thus
limited to some duty cycle, our implementation is fully passive and thus
provides the potential for unprecedented quantum communication speeds. We
experimentally demonstrate the feasibility of our approach using a single
source of bi-partite polarization entanglement which is multiplexed into 12
wavelength channels to distribute 6 states between 4 users in a fully connected
graph using only 1 fiber and polarization analysis module per user.
