Implementation of a nonlocal N-qubit conditional phase gate using the nitrogen–vacancy center and microtoroidal resonator coupled systems

Implementation of a nonlocal multi-qubit conditional phase gate is an essential requirement in some quantum information processing (QIP) tasks. Recently, a novel solid-state cavity quantum electrodynamics (QED) system, in which the nitrogen–vacancy (NV) center in diamond is coupled to a microtoroidal resonator (MTR), has been proposed as a potential system for hybrid quantum information and computing. By virtue of such systems, we present a scheme to realize a nonlocal N-qubit conditional phase gate directly. Our scheme employs a cavity input–output process and single-photon interference, without the use of any auxiliary entanglement pair or classical communication. Considering the currently available technologies, our scheme might be quite useful among different nodes in quantum networks for large-scaled QIP. (general)