Scheme for N-Qubit Toffoli Gate by Transport of Trapped Ultracold Ions

We propose a potentially practical scheme for implementing an n-qubit Toffoli gate by elaborately controlling the transport of ultracold ions through stationary laser beams. Conditioned on the uniform ionic transport velocity, the n-qubit Toffoli gate can be realized with high fidelity and high successful probability under current experimental conditions,which depends on a single resonant interaction with n trapped ions and has constant implementation time with the increase of qubits. We show that the increase of the ion number can improve the fidelity and the successful probability of the Toffoli gate.