利用Ket-Bra纠缠态方法, 求解了原子与热库相互作用系统中的密度矩阵主方程, 得到了密度矩阵的演化表达式.考虑三个二能级原子独立与热库相互作用的情况, 利用负本征值度量三体纠缠, 研究了系统中原子间的三体纠缠特性.采用数值计算方法, 讨论了热库平均光子数和原子自发辐射率对原子间三体纠缠特性的影响.研究结果表明: 随原子自发辐射率和热库平均光子数的增大, 原子间的三体纠缠衰减加快.

The master equation of the density operator in the system of atom interacting with thermal reservoir was concisely solved by virtue of Ket-Bra entangled state. Analytical solution expression of the master equation was given. Considering that each of atoms interacts with thermal reservoir respectively, negativity was adopted to quantify the degree of tripartite entanglement among three atoms, and properties of tripartite entanglement among atoms were investigated. The influences of mean photon of the thermal reservoir and atomic spontaneous emission rate on properties of tripartite entanglement were discussed by using the numerical method. The results show that the tripartite entanglement among atoms decays accelerating with the increase of mean photon of the thermal reservoir and atomic spontaneous emission rate.