The Application Of Cavity Qed Two-bit Quantum Logic Gates And Preparation Of Multi-bit Entangled State

We propose a simple scheme for realizing basic two-qubit logic gates with anatom inside a circular polarized bimodal cavity. Our scheme is based on resonantinteraction of an atom with cavity modes, a two-qubit quantum phase gate and aswap gate are performed by only one step, and the controlled-NOT gate can also beimplemented from a quantum phase gate. In consideration of atomic spontaneousemission and cavity decay, the quantum logic gates can be implemented probabilis-tically, the success probability and fidelity are approach to 1 in strong couplinglimit. Our scheme can be generalized to generate multiqubit entangled state by oneatom interacting with multipartite cavities or multipartite atoms interacting withone cavity resonantly, the process for generating multiqubit entangled state is sim-plifying by applying our model, the interaction time is short, the decoherence canbe suppressed effectively, so it is feasible in experiment.