  Scalable quantum information processing will require quantum networks of
qubits with the ability to coherently transfer quantum states between the
desired sender and receiver nodes. Here we propose a scheme to implement a
quantum router that can direct quantum states from an input qubit to a
preselected output qubit. The path taken by the transferred quantum state is
controlled by the state of one or more ancilla qubits. This enables both
directed transport between a sender and a number of receiver nodes, and
generation of distributed entanglement in the network. We demonstrate the
general idea using a two-output setup and discuss how the quantum routing may
be expanded to several outputs. We also present a possible realization of our
ideas with superconducting circuits.
