耗散腔中两二能级原子态的自旋压缩量子Fisher信息和最大自旋涨落

Spin squeezing,quantum Fisher information and maximal spin fluctuation of a pair atom with two-level in the dissipative cavity

在能量耗散腔中,原子用泡利算符描述,光场用相干态描述,运用密度矩阵理论,得到了两二能级原子密度矩阵元的演化规律,分析了与单模辐射场作用过程中原子态的自旋压缩、量子Fisher信息和最大自旋涨落.结果表明:自旋压缩,大于1/2的最大自旋涨落可以作为量子纠缠的充分必要判据.自旋压缩,大于1/2的最大自旋涨落和量子纠缠,它们互相等价.大于1的Fisher信息与它们之间没有等价关系,但可以作为自旋压缩和量子纠缠的充分判据.

In this paper, the two-level atom is described by Pauli sign and the optical field is described by coherent state. The two-level atoms＇ reducible density rectangular array is obtained using the density matrix theory. We discuss the spin squeezing, the quantum Fisher information and the maximal spin fluctuation of quantum state of two-level atoms interacting with a single-mode field in a dissipative cavity. The results show that the spin squeezing and the maximal spin fluctuation is more the unity can be regarded as the sufficiency and necessary criterion for the entanglement. The spin squeezing, the maximal spin fluctuation which is more than unity and concurrence is equivalent to each other. But the quantum Fisher information, which is more the unity, do not equivalent to them and can be regarded as suffi- ciency criterion for the entanglement and the spin squeezing.