Three-way entanglement and three-qubit phase gate based on a coherent six-level atomic system

摘要

We analyze the nonlinear optical response of a six-level atomic system under a configuration of electromagnetically induced transparency. We show that the enhanced completely cross fifth-order nonlinearity generated in such a system can be used to produce efficient three-way entanglement and to realize a three-qubit quantum phase gate. We demonstrate that such phase gate can be transferred to an all-optical Toffoli gate, facilitating practical applications in quantum information and computation.