  By simultaneously coupling multiple two-level artificial atoms to two
superconducting resonators, we design a quantum switch that tunes the
resonator-resonator coupling strength from zero to a large value proportional
to the number of qubits. This process is implemented by engineering the qubits
into different subradiant states, where the microwave photons decay from
different qubits destructively interfere with each other such that the
resonator-resonator coupling strength keeps stable in an open environment.
Based on a three-step control scheme, we switch the coupling strength among
different values within nanoseconds without changing the transition frequency
of the qubits. We also apply the quantum switch to a network of superconducting
resonators, and demonstrate its potential applications in quantum simulation
and quantum information storage and processing.
