Fast and effective implementation of discrete quantum Fourier transform via virtual-photon-induced process in separate cavities

We present a fast and effective scheme to implement the multiqubit discrete quantum Fourier transform (DQFT) for distant atoms trapped in separate cavities connected by optical fibers via a virtual-photon-induced process. The effective coupling between two distributed atoms is achieved without exciting and transporting photons through the optical fiber, and the gate operation is robust against the decoherence effect when the thermal photons in the environment are negligible. The implementation of the scheme is appealingly simple because the complex combination of quantum gate operations, which act on each two qubits in the rearranged DQFT circuit, is achieved only in one step through the interaction controlled by optical switches between two adjacent cavities. The scheme opens promising perspectives for scalable quantum communication networks and distributed quantum computation. (C) 2012 Optical Society of America