  A single-photon switch is an important element for the building of scalable
quantum networks. In this paper, we propose a feasible scheme for efficient
single-photon switching. The proposed switch is controlled by a state of a
qubit formed by the pair of the lowest levels of a three-level system (qutrit)
coupled to a resonator. This resonator-qutrit system comprises a switching unit
of the considered setup. For suppression of the Purcell relaxation of the
control qubit, the switching unit is embedded into a coupled-resonator array
serving as an engineered electromagnetic environment with a band gap on a qubit
transition frequency. We discuss the possible implementation of the considered
single-photon switch on the microwave circuit QED architecture. We demonstrate
that high switching contrasts can be attained for the parameters achievable for
the state-of-the-art superconducting circuit QED setups.
