【作者】 李燕丽；

【导师】 梁麦林；

【作者基本信息】 天津大学 ， 理论物理， 2005， 硕士

【摘要】 光场与原子的相互作用一直是量子光学研究的重要内容之一。1963年Jaynes和Cummings用纯量子的方法描述了一个二能级原子与单模光场相互作用的物理模型(JCM)。物理学家们对此模型作了大量的研究,并作了多种形式的推广。利用这些模型对纠缠特性的研究在量子通讯方面具有重要的地位。但对运动两能级原子与光场的共振拉曼相互作用中的纠缠特性还未见报道。本文研究原子与双模压缩真空态光场相互作用中的纠缠特性,考虑了共振拉曼相互作用的情况,同时计入了原子运动的影响。原子运动是一种实际的因素,应该加以考虑。利用量子约化熵和量子相对熵分别研究了双模压缩真空态光场与原子相互作用中两者的纠缠(简称场-原子纠缠)性质和双模光场的模间纠缠(简称模间纠缠)性质。揭示了双模压缩真空态光场和原子配制成不同的状态时,二者对场熵特性的影响。我们发现:当不考虑原子运动时,增大压缩因子r,场-原子间纠缠增强而且持续时间增大。而当考虑原子运动时,场模参数p和原子初态θ较小同时压缩因子r较大时,场-原子间纠缠增强而且持续时间增大,模间纠缠与场-原子纠缠相反。从而得出了通过选择合适的系统参数和时间,双模压缩真空态光场与原子间以及双模压缩真空态光场模间都仍可保持较好的纠缠特性,这对于用量子纠缠实现量子通讯具有重要的指导意义。更多还原

【Abstract】 It is important that optical fields interact with atoms in quantum optics. In 1963,Jaynes and Cummings described a physical model of two-level atom and one modeoptical field named J-C model. Physicists do many studies and expansions. Theyassume that atom is still and only think of the inner interaction of atom with theoptical fields, a moving two-level atom interacting with two_mode field through resonanceRaman process are not investigated, we’ll study it in this paper.In this article, we study the interaction between two-mode squeezing vacuumstate and a moving two-level atom by two-photon resonance Raman process inquantum theory. We shoud consider the motion of atom because it’s a factualreason .We respectively investigate the entanglement of the two-mode field and atomand the one of two modes field using the quantum reduced entropy and the quantumrelative entropy and analysis the entropy properties in different state.We discover that when we don’t consider the moving of atom , the quantumentanglement of atom and the two-mode field becomes high and keeps long at highsqueezing parameter r , also, when atom moves, it’s the same result at low fieldparameter p and atom state parameter θ. So we can conclude that the two-mode fieldand the moving two-level atom, also with the moving two-level atom they still havethe better character of quantum entanglement, choosing proper systematical parameterand time. It is important to quantum entanglement in quantum .更多还原