非等同两个原子与双模腔场相互作用模型中双原子偶极振幅平方压缩

本文研究了具有不同耦合系数的两个二能级原子与双模腔场相互作用系统中原子偶极振幅平方压缩随时间的演化规律.并讨论了两个原子与双模腔场的相对耦合常数(R=g1/g2)和腔场的初态对原子偶极振幅平方压缩的影响.     

Effects of Cavity-Field Statistics on Atomic Entanglement in Two-Mode Jaynes-Cummings Model

We study the entanglement properties of a pair of two-level Rydberg atoms passing one after another into a lossless cavity with two modes. The initial joint state of two successive atoms that enter the cavity is unentangled. Interactions mediated by the cavity field results in the final two-atom mixed entangled type state. The entanglement of formation of the joint two-atom state as a function of the Rabi angle gt is calculated for Fock state field, coherent field and thermal field respectively inside the cavity. We present a comparative study of two-atom entanglement corresponding to the different field statistics.     

两个级联型三能级原子受激辐射的非线性性质

本文研究了两个级联型三能级原子同单模腔场的非线性相互作用,研究表明:在激发场场强达到一定阈值以后,两个原子的合作辐射效应变成同步辐射,即多原子系统在一定阈值条件下可以有组织成相当于一个大原子的系统,而产生同步有序辐射。同时,由于这种同步辐射效应,两原子系统的受激辐射的二阶相干度相对于单原子系统的要大,即聚束效应强而反聚束效应弱。另外,两原子系统由于多光子过程的加强而有更深的压缩效应,此时要求的激发场场强也比单原子系统的要强。     

两个级联型三能级原子受激辐射的非线性性质

本文研究了两个级联型三能级原子同单模腔场的非线性相互作用.研究表明: 在激发场场强达到一定阈值以后, 两个原子的合作辐射效应变成同步辐射, 即多原子系统在一定阈值条件下可以有组织成相当于一个大原子的系统, 而产生同步有序辐射. 同时, 由于这种同步辐射效应, 两原子系统的受激辐射的二阶相干度相对于单原子系统的要大, 即聚束效应强而反聚束效应弱. 另外, 两原子系统由于多光子过程的加强而有更深的压缩效应, 此时要求的激发场场强也比单原子系统的要强. 关键词：     

Dynamics of the two-atom Jaynes-Cummings model with nondegenerate two-photon transitions

An exact solution is found for the collective model of two identical two-level atoms that resonantly interact with a two-mode quantum electromagnetic field in an ideal cavity via two-photon nondegenerate transitions. In the case under study, at the initial moment, both field modes are in the coherent state and atoms are in the excited state. The time dependences of the atomic probabilities, the mean number of photons in the modes, and the statistics and squeezing of the photon modes are studied based on the exact solution.     

Evolution of Atomic Entanglement for Different Cavity-Field Statistics in Single-Mode Two-Photon Process

We study the evolution of entanglement for a pair of two-level Rydberg atoms passing one after another into an ideal cavity filled with a single mode radiation field. The atoms interact with the cavity field via two-photon transitions. The initial joint state of two atoms that enter the cavity one after the other is unentangled. Interactions intervened by the single mode cavity photon field brings out the final two-atom mixed entangled type state. We use the well known measure appropriate for the mixed states, i.e. the entanglement of formation to quantify the entanglement. We calculate the entanglement of formation of the joint two-atom state as a function of the Rabi angle, for the Fock state field, coherent field and thermal field respectively inside the cavity. The change in the magnitude of atomic entanglement with cavity photon number has been discussed.     

Bell态原子与双模纠缠相干光场相互作用的纠缠特性

运用Negativity熵研究了Bell态原子与双模纠缠相干光场相互作用系统中两个全同二能级原子之间的纠缠演化特性.分析了光场强度、光场纠缠度及原子间相互作用强度对纠缠的影响.结果表明:原子处于|β11〉时,两原子始终处于最大纠缠态;原子处于|β00〉时,初始纠缠的两原子始终较长时间处于退纠缠状态;原子处在|β10〉时,增大双模光场的平均光子数可以明显增大两原子之间的纠缠度并保持较大的纠缠状态;原子初态处在|β01〉时,原子间的相互作用强度对双原子间纠缠度有较显著的非线性调制作用.     

Single-atom entropy squeezing and quantum entanglement in Tavis--Cummings model with atomic motion

We examine the single-atom entropy squeezing and the atom-field entanglement in a system of two moving twolevel atoms interacting with a single-mode coherent field in a lossless resonant cavity.Our numerical calculations indicate that the squeezing period,the squeezing time and the maximal squeezing can be controlled by appropriately choosing the atomic motion and the field-mode structure.The atomic motion leads to a periodical time evolution of entanglement between the two-atom and the field.Moreover,there exists corresponding relation between the time evolution properties of the atomic entropy squeezing and that of the entanglement between the two atoms and the field.     

多光子Tavis-Cummings模型中两纠缠原子的纠缠演化特性

研究了两个纠缠的二能级原子通过多光子跃迁与单模相干光场进行耦合相互作用系统中两原子纠缠的演化特性.计算分析表明,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、原子间的偶极相互作用、相干光场的参数以及跃迁光子数对两个原子的纠缠有着显著的影响;并发现两原子初始处于某最大纠缠态时,两原子会永远处于该最大纠缠态,因此这一类最大纠缠态可以作为一种量子信息存储器. 关键词： 量子纠缠 部分转置矩阵负本征值 纠缠原子 相干态     

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.     

原子的选择测量对原子纠缠特性和场熵的影响*

考虑初始处于W态的三个二能级原子,将其中两个原子同时注入处于真空态的单模腔中,并与光场发生共振相互作用的情况。采用数值计算方法,通过对是否进行原子态选择性测量情况下,腔内原子间的纠缠性质和场熵的比较,讨论了对腔外原子的态选择性测量对腔内原子间的纠缠性质和场熵演化的影响。研究结果表明：对腔外原子的选择性测量,可增强腔内原子间的纠缠,但会减弱腔內原子与光场的关联。     

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     

压缩现象与光子统计分布

本文研究压缩现象与光子统计分布之间的关系。通过逐次注入处于激发态的原子,无损光学腔内的光子数概率分布会有有趣的变化,腔场有可能取得较深的压缩。 关键词：     

腔损对单原子微激射器中产生稳定四阶与振幅平方压缩态的影响

研究了利用相干陷落方法在单原子微激射器中产生具有四阶压缩和振幅平方压缩性质的稳态腔场.结果表明,在目前微激射器实验的腔损条件下,如果注入腔中的原子初始处于相干态,只要原子束的通量适当大,当原子在腔中的飞行时间满足陷落条件时,腔场可进入相干陷落态,此时腔场呈现稳定的四阶压缩和振幅平方压缩性质 关键词：     

Influence of selective atomic measurement on the entanglement properties of a two-atom outside cavity

Considering three two-level atoms initially in the W or Greenberger--Horne--Zeilinger (GHZ) state, one of the three atoms is put into an initially coherent light cavity and made to resonantly interact with the cavity. The two-atom entanglement evolution outside the cavity is investigated. The influences of state-selective measurement of the atom inside the cavity and strength of the light field on the two-atom entanglement evolution outside the cavity are discussed. The results obtained from the numerical method show that the two-atom entanglement outside the cavity is strengthened through state-selective measurement of the atom inside the cavity. In addition, the strength of the light field also influences the two-atom entanglement properties.     

Kerr介质中耦合V型三能级原子与相干态光场作用场的量子性质

研究了Kerr介质中相干态光场与耦合V型三能级原子相互作用过程中场的量子性质.利用量子光学中光场与原子相互作用的耦合Tavis-Cummings模型,对系统的动力学过程进行了求解.讨论了系统初始状态、失谐量、原子间偶极相互作用强度及Kerr系数对光场量子性质随时间演化的影响.数值计算结果表明:初态中场的平均光子数比较小时,光场能够展现出明显的量子效应|初始时刻原子激发态概率幅从小变大时,光场的反聚束效应变得越明显,而光场的压缩深度会先增大后减小|失谐量的变化对场的量子性质的影响不大,只是改变光场二阶相关函数和压缩参量振荡的周期|原子间耦合强度的增大使光场的反聚束效应减弱和光场的压缩深度变浅|Kerr系数的增大会增强光场的反聚束效应,而使光场的压缩深度变浅.     

Role of spatial mode function in the presence of two-atom events in a micromaser

In this paper, we discuss the effects of spatial mode function in an one-photon micromaser in the presence of two-atom events. It is shown that two-atom events allow us a possibility to study the effects of different cavity eigenmodes in a micromaser. We find that squeezing properties of the radiation field depend upon the parity (odd or even) and order (lower or higher) of cavity eigenmodes. For example, squeezing can be obtained for odd-order cavity eigenmodes which completely vanishes for even-order modes. Our results also show that effects similar to self-induced transparency are never obtained in the presence of two-atom events. Finally, we consider the effect of pump fluctuations and cavity losses in our system.     

远程控制纠缠原子的偶极压缩

考虑初始处于EPR态的两个二能级原子A、B,将B原子注入处于真空态和单光子态的叠加态的腔中,演化一段时间后,对B原子进行选择性测量,通过选择合适的腔场初始叠加状态和演化时间,可控制原子A的偶极矩压缩效应.     

Entanglement Dynamics and Bell Violations of Two Atoms in Tavis-Cummings Model with Phase Decoherence

Considering the dipole-dipole coupling intensity between two atoms and the field in the Fock state, the entanglement dynamics between two atoms that are initially entangled in the system of two two-level atoms coupled to a single mode cavity in the presence of phase decoherence has been investigated. The two-atom entanglement appears with periodicity without considering phase decoherence, however, the phase decoherence causes the decay of entanglement between two atoms, with the increasing of the phase decoherence coefficient, the entanglement will quickly become a constant value, which is affected by the two-atom initial state. Meanwhile the two-atom quantum state will forever stay in the maximal entangled state when the initial state is proper even in the presence of phase decoherence. On the other hand, the Bell violation and the entanglement do not satisfy the monotonous relation, a large Bell violation implies the presence of a large amount of entanglement under certain conditions, while a large Bell violation corresponds to a little amount of entanglement in certain situations. However, the violation of Bell-CHSH inequality can reach the maximal value if two atoms are in the maximal entangled state, or vice versa.     

单模辐射场与耦合双原子相互作用系统中场熵的压缩特性

研究了单模辐射场与耦合双原子相互作用系统中场熵的压缩特性,讨论了系统初始状态及原子间偶极相互作用对场熵压缩特性的影响.数值计算结果表明,当系统初始时刻处于合适的相干叠加态时,场熵呈现出周期性压缩现象,其压缩深度和压缩时间与原子间偶极相互作用强度有关. 关键词： 单模辐射场 耦合双原子 光场熵压缩