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Based on the quantum Zeno dynamics, a scheme is presented to implement a Toffoli gate of three separated superconducting qubits (SQs) by one step. Three separated SQs are connected by two resonators. The scheme is insensitive to the resonator decay because the Zeno subspace does not include the state of the resonators being excited. Numerical simulations indicate that the scheme is robust to the fluctuation of the parameters and the Toffoli gate can be implemented with high fidelity.

A scheme is reported for the teleportation of entangled coherent states through the degenerate Raman interaction. The scheme uses an entangled state of an atom and two coherent states as a quantum channel. It makes full use of coherent cavity fields. Furthermore, it does not need any classical field to transform the atom states.

A scheme is proposed to generate W state of N atoms trapped in a cavity, based on adiabatic passage along dark state. Taking advantage of adiabatic passage, the atoms have no probability of being excited and thus the atomic spontaneous emission is suppressed. The scheme is simple. It does not need to adjust the interaction time accurately, and does not need to prepare the cavity field in one-photon state. Numerical simulation shows that the successful probability of the scheme increases with the increasing of the atom number.

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