Secure quantum routing

Abstract: We show that a quantum network can protect the identity of a sender and receiver from an external wiretapper. This new quantum communication protocol, which we call secure quantum routing, requires only single photons routed by linear optical elements and photon counters, and does not require distributing entanglement over multiple nodes or active feedforward. We prove that secure quantum routing protects both the contents of the message and the identity of the sender and receiver, and creates only a negligible reduction in the network channel capacity.