中文摘要：

利用量子约化熵对比研究了真空、一维腔、各向同性以及各向异性光子晶体四种不同结构库中二能级原子与自发辐射场间的纠缠演化特性。研究表明，原子-光场纠缠的演化特性与原子所处结构库的模密度分布密切相关。在真空和一维腔中，模密度随频率连续变化，原子-光场纠缠将最终衰减至零。而在各向同性和各向异性光子晶体中，模密度中存在光子禁带，原子-光场纠缠能最终趋于稳态值。可以通过改变原子所处结构库的模密度来控制原子-光场纠缠的演化特性。

英文摘要：

The time evolutions of the entanglement between a two-level atom and its spontaneous emission field in free space, cavity, isotropic and anisotropic photonic crystal are studied by using quantum entropy. It is found that the evolution properties of the atom-field entanglement are directly related to the nature of the structured reservoir,specifically, to the distribution of the density of modes. In free space and cavity, as the density of the modes varies smoothly with frequency, the atom-field entanglement decays to zero in a finite time. However in an isotropic and anisotropic photonic crystal, the atom-field entanglement can keep steady due to the existence of a photonic band gap in the density of the modes. Thus, we can control the time evolution of the entanglement between the atom and its spontaneous emission field by changing the density of the modes of the structured reservoirs.