Fast multiqubit phase gate in circuit QED beyond the rotating-wave approximation

Abstract

We propose a two-step approach to realize a multiqubit phase gate in circuit QED beyond the rotating-wave approximation. The multiqubit gate can be implemented in a few nanoseconds, which is much faster than that under the rotating-wave approximation. Also the operation time of the gate is independent of the number of qubits. Due to the absence of the resonator degree of freedom in the effective Hamiltonian, our scheme is insensitive to the initial state of the resonator and immune to the leakage of photons. Numerical simulation shows that the scheme is robust against the main decoherence sources.