耗散系统中原子和场的熵交换与纠缠

研究耗散腔中, 二能级原子与单模辐射场在相互作用过程中熵关联的情况. 结果表明：原子与场之间存在熵交换现象, 更重要的是证明了它们之间的熵交换需要满足一定的条件. 同时也计算了原子与场之间的纠缠, 发现两子系统间熵交换与纠缠的关系.     

光场与纠缠双原子相互作用过程中的熵演化特性

研究了单模光场与纠缠双原子相互作用过程中熵的演化特性，讨论了双原子纠缠度与初始光场强度对场熵演化特性的影响.研究结果表明，双原子纠缠度影响场熵的平均值，而初始光场的强度则影响场熵演化的振荡特性. 关键词： 单模辐射场 纠缠双原子 场熵演化     

耗散系统中原子和场的熵交换与纠缠

研究耗散腔中,二能级原子与单模辐射场在相互作用过程中熵关联的情况。结果表明：原子与场之间存在熵交换现象,更重要的是证明了它们之间的熵交换需要满足一定的条件。同时也计算了原子与场之间的纠缠,发现两子系统间熵交换与纠缠的关系。     

Tavis-Cummings模型中两纠缠原子纠缠的演化特性

研究了两个纠缠的两能级原子与单模粒子数场进行相互作用系统中两原子的纠缠演化.结果表明：两个原子之间的纠缠呈现出周期性的演化特性，初始两原子的状态、原子之间的偶极相互作用和粒子数场对腔中两个原子的纠缠有着显著的影响.发现适当选择原子的初态，两原子会永远处于最大纠缠态. 关键词： 量子纠缠 偶极-偶极相互作用 部分转置矩阵负本征值 纠缠原子     

纠缠Ξ-型三能级原子与纠缠腔场相互作用熵的纠缠演化

文章利用一对处于纠缠态的-型三能级原子与一对处于纠缠态的单模腔场,初始时刻原子与腔场之间互不纠缠,使其中一个原子与一个腔场发生相互作用,即纠缠交换,合适选择相互作用时间就可实现原子与腔场之间产生纠缠,并研究了系统原子熵的演化特性,运用量子熵理论,讨论了原子-腔场的耦合常数对原子熵的影响,结果表明：原子与光场跃迁耦合常数对系统熵的最大纠缠度有影响.当原子与光场两种跃迁耦合常数之比k值增大时,最大纠缠度在减小;当k增大到某一程度时,系统熵随时间周期性变化,并出现双峰现象。     

三纠缠原子与双模腔场相互作用系统的纠缠演化特性

研究了初始处于GHZ态的三个两能级原子与双模腔场相互作用系统的纠缠动力学特性,得到了并发度和线性熵的解析表达式.讨论了腔场初始纠缠度对腔内两原子之间纠缠的影响,对其余子系统求迹后结果表明腔内两原子之间的纠缠出现突然产生现象,腔内两原子之间产生纠缠的阈值时间和最大值依赖于双模腔场初始纠缠度;并且发现腔内两原子子系统和腔外原子与场子系统之间在整个的时间演化过程中一直保持着纠缠状态.     

远程制备双原子纠缠态

提出一种远程制备双原子纠缠态的方案,该方案基于两个原子与单模腔场的同时非共振相互作用.由于双粒子纠缠态比三粒子纠缠态容易制备,方案用两对双原子纠缠态作为量子通道.Alice 拥有的两个相同原子同时与一单模腔场非共振相互作用.Alice已知她要制备的纠缠态,她选择适当的相互作用时间、测量她所拥有的两个原子并通过经典通道通知Bob.Bob引入一个相同的辅助原子和一个单模腔场来实现方案.方案对腔场状态和腔损耗不敏感,基于当前的腔QED 技术,方案能在实验上实现.该方案有望在量子信息过程中有重要的应用价值.     

原子-腔-光纤复合系统中的纠缠特性

采用Negativity熵来描述两子系统间的纠缠,研究了由两个二能级原子与光纤联接的单模腔构成的系统的纠缠特性.利用数值计算方法讨论了原子与腔场的耦合强度和原子选择性测量对纠缠特性的影响.研究结果表明:对一个原子的选择性测量,可增强原子间与腔场间和腔场与腔场间的纠缠.     

原子-腔-光纤复合系统中的纠缠特性

采用Negativity熵来描述两子系统间的纠缠,研究了由两个二能级原子与光纤联接的单模腔构成的系统的纠缠特性.利用数值计算方法讨论了原子与腔场的耦合强度和原子选择性测量对纠缠特性的影响.研究结果表明:对一个原子的选择性测量,可增强原子间与腔场间和腔场与腔场间的纠缠.     

耦合腔系统中的三体纠缠演化

研究由耦合腔和四个全同的二能级原子构成的系统中三体纠缠态纠缠量的演化. 四个原子分别囚禁在单模耦合腔A和B中, 并且原子通过单光子跃迁与腔场发生共振相互作用. 采用纠缠张量方法, 通过数值计算研究了每个腔中三体纠缠的演化. 讨论了原子与腔场间的耦合强度对三体纠缠演化的影响. 研究结果表明: 原子与腔场间的两体纠缠强于原子间的两体纠缠, 每个腔中的三体纠缠是两体纠缠相干叠加的结果.     

耗散腔场中两个∧型原子的纠缠特性

利用超算符方法求解幅值损耗腔中两个∧型三能级原子与相干光场相互作用系统的主方程,并利用量子条件熵研究了两个初始为|Ψa(0)＞和|Φa(0)＞纠缠态的原子与光场作用过程中原子的纠缠演化特性.讨论了不同初始原子纠缠度,不同耗散系数以及不同平均光子数对两原子纠缠度的影响.结果表明:①当原子初始处于|Ψa(0)＞类纠缠态时,其纠缠度随光场强度以及腔场衰减系数演化.当腔不存在耗散时,纠缠度呈周期性振荡;当腔存在耗散时,纠缠度呈衰减振荡并趋于稳定值;且光强越弱,其稳定值越大;衰减系数越大纠缠达到稳定值所需时间越短.②原子初始处于|Φa(0)＞类纠缠态时,其纠缠度只与原子初始纠缠度有关,不随其他因素变化.     

Control and Transfer of Entanglement between Two Atoms Driven by Classical Fields under Dressed-State Representation

We have studied the dynamics and transfer of the entanglement of the two identical atoms simultaneously interacting with vacuum field by employing the dressed-state representation. The two atoms are driven by classical fields. The influence of the initial entanglement degree of two atoms, the coupling strength between the atom and the classical field and the detuning between the atomic transition frequency and the frequency of classical field on the entanglement and atomic linear entropy is discussed. The initial entanglement of the two atoms can be transferred into the entanglement between the atom and cavity field when the dissipation is neglected. The maximally entangled state between the atoms and cavity field can be obtained under some certain conditions. The time of disentanglement of two atoms can be controlled and manipulated by adjusting the detuning and classical driving fields. Moreover, the larger the cavity decay rate is, the more quickly the entanglement of the two atoms decays.     

The entanglement evolution between two entangled atoms

The entanglement properties of two entangled atoms interacting with the field under intensity-dependent coupling are studied in detail. It is found that the degree of entanglement between the two atoms changes periodically and undergoes the entanglement sudden death (ESD) and sudden birth at some time. The entanglement properties between the field and the atom inside the cavity are dependent on the photon number. Most interestingly, the entanglement between the field and the atom in the field is influenced significantly by manipulating the atom outside the field.     

Entanglement swapping between atom and cavity and generation of entangled state of cavity fields

This paper proposes a scheme where entanglement swapping between atom and cavity can be realized. \Lambda -type three-level atoms interacting resonantly with cavity field are considered. By detecting atom and cavity field, it realizes entanglement swapping between atom and cavity. It uses the technique of entanglement swapping to generate an entangled state of two cavity fields by measuring on atoms. It discusses the experimental feasibility of the proposed scheme and application of entangled state of cavity fields.     

INFLUENCE OF ENTANGLEMENT DEGREE ON SQUEEZING AND PHOTON ANTIBUNCHING IN THE JAYNES-CUMMINGS MODEL

We consider the case that one of entangled atoms interacts with a single-mode cavity field. The atom is selectively detected after exiting the cavity, and it is found that the nonclassical properties of field states depend strongly on the entanglement degree between the two atoms. Meanwhile it is proven that squeezing of field and photon antibunching can be greatly enhanced via selective atomic measurements.     

纠缠度对双光子Jaynes-Cumming模型的光学效应的影响

研究了一对纠缠的二能级原子之一与单模双光子腔场的相互作用，当该原子离开腔被选择性测量时，发现场态的非经典特性很大程度上取决于两原子间的纠缠度。同时发现通过对原子的选择性测量，场的压缩特性和光子的反聚束效应会增强。 关键词： 纠缠度 Jaynes-Cumming模型 压缩效应 光子反聚束效应     

Entanglement properties between two atoms in the binomial optical field interacting with two entangled atoms

The temporal evolution of the degree of entanglement between two atoms in a system of the binomial optical field interacting with two arbitrary entangled atoms is investigated. The influence of the strength of the dipole–dipole interaction between two atoms, probabilities of the Bernoulli trial, and particle number of the binomial optical field on the temporal evolution of the atomic entanglement are discussed. The result shows that the two atoms are always in the entanglement state. Moreover, if and only if the two atoms are initially in the maximally entangled state, the entanglement evolution is not affected by the parameters, and the degree of entanglement is always kept as 1.     

Stark效应对量子纠缠信息交换传递的影响

用多个“二能级原子与单模光场”组成的联合物理模型,考虑Stark效应后,推导了该系统的态矢演化式,得到光场纠缠度的数值计算结果.讨论了Stark效应和初始场强对量子纠缠信息交换传递的影响.结果发现,在一定条件下,原子纠缠态与光场纠缠态之间可以转化,实现了量子纠缠信息的交换传递,且Stark效应和初始场强对此过程有着显著的影响:光场的纠缠程度随着初始场强的增强而增大;在强场条件下,光场纠缠度出现崩塌-回复现象.Stark移位参量越大,光场纠缠度振荡越剧烈,说明Stark效应破坏了光场纠缠程度的稳定性.     

Entropy evolvement properties in a system of Schrodinger cat state light field interacting with two entangled atoms

The field entropy can be regarded as a measurement of the degree of entanglement between the light field and the atoms of a system which is composed of two-level atoms initially in an entangled state interacting with the Schr\"{o}dinger cat state. The influences of the strength of light field and the phase angle between the two coherent states on the field entropy are discussed by using numerical calculations. The result shows that when the strength of light field is large enough the field entropy is not zero and the degrees of entanglement between the atoms and the three different states of the light fields are equal. When the strength of the light field is small, the degree of entanglement is maximum in a system of the two entangled atoms interacting with an odd coherent state; it is intermediate for a system of the two entangled atoms interacting with the Yurke--Stoler coherent state, and it is minimum in a system of the two entangled atoms interacting with an even coherent state.