Raman型原子—腔场系统N-qubit原子态的隐形传送

利用全量子理论,对简并A型三能级原子与单模相干态的相反态腔场之间的Raman相互作用进行了详细研究.在此基础上,提出了利用简并A型三能级原子与腔场之间的Raman相互作用,来隐形传送N-qubit未知原子态的新方案.     

非简并拉曼过程中交流斯塔克位移对场相位性质的影响

应用Pegg-Barnett相位理论,研究了非简并Raman耦合过程中双模光场相应的演化特性,讨论了原子相干性和能级的交流Stark位移对场相位概率分布、相位扩散及频率漂移的影响。     

非简并双光子Tavis-Cummings模型中的纠缠演化

研究了两对非相互作用、空间分离的原子在双模腔场作用下的三体和两体纠缠动力学行为。对非简并双光子Tavis-Cummings模型进行了研究,通过数值计算分析了纠缠初始状态、原子与腔场以及光纤模与腔场的耦合强度对纠缠的影响。结果表明:纠缠初始状态对原子间的纠缠有显著影响;较大的场和光纤模的耦合强度可以实现原子与原子间最大纠缠的转移;较大的原子与腔场耦合强度有助于两原子与腔场构成三体纠缠。     

原子间偶极相互作用对非简并双模T－C模型中原子布居及光场性质的影响

讨论了非简并双模光场与两个两能级原子相互作用的Ｔａｖｉｓ－Ｃｕｍｍｉｎｇｓ（Ｔ－Ｃ）模型中原子偶极－偶极耦合对辐射场的相关特性和原子布居的影响。     

原子间偶极相互作用对非简并双模T—C模型中原子布居及光场性质的影响

讨论了非简并双模光场与两个两能级原子相互作用的Ｔａｖｉｓ－Ｃｕｍｍｉｎｇｓ（Ｔ－Ｃ）模型中原子偶极－偶极耦合对辐射场的相关特性和原子布居的影响。     

关于非线性光学中的相互作用哈密顿量

本文讨论了非线性光学中Shen-Walls哈密顿量存在的问题。我们得到的结论是:该哈密顿量的经典出发点是不正确的;在宏观非线性极化模型下,辐射场与原子相互作用的多极形式哈密顿量不能推广到非线性相互作用的情形;严格的非线性相互作用哈密顿量是集合模形式(Collective ma-     

场频率变化对辐射场与原子间耦合系数的影响

对二能级原子与单模辐射场相互作用系统的哈密顿量进行分析,找出光场与原子之间耦合系数与光场频率及谐振腔体积之间的关系。通过利用谐振腔的腔镜振动机制,研究了腔镜振动对光场模式及对腔体积的影响,最终找出辐射场与原子之间耦合系数与场频变化之间的关系。     

依赖强度耦合的简并量子拍三能级原子的偶极压缩效应

原子偶极压缩是原子与光场相互作用的一种重要现象,但迄今很少见到依赖强度耦合的三能级原子偶极压缩效应的讨论.采用全量子论方法研究了与单模相干光场相互作用的依赖强度耦合的简并量子拍三能级原子的偶极压缩时间演化特性,讨论了原子下能级裂距、光场强度及初原子态相干性对原子偶极压缩的影响.结果表明,当原子两下能级简并时,原子偶极参量随时间周期性演化,原子两下能级裂距破坏这种周期性并降低压缩量.原子偶极压缩量与初始相干光场强度之间关系不是单调的.原子相干性对原子偶极压缩效应有重要影响.     

原子初态对双频场作用的三能级原子动力学行为的影响

求得双频场作用下串接型三能级原子系统哈密顿量的本征函数和本征值。从而得到原子初态任意、偏调任意情况下原子随时间的演化。给出了原子布居数和原子极化与初始原子状态的关系和与偏调的关系公式。研究了原子动力学行为与入射光强、偏调、二入射光场的相对相位以及原子初始状态的关系。揭示了原子初始相位和光场相位对原子光相互作用大小的影响。当相对相位为π时,原子与场耦合最小,在特殊情况下原子与场耦合为零,即原子与场无相互作用。     

∧和∨型单模激光的朗之万理论

采用激光朗之万理论研究具有非简并能级和任意衰减常数的三能级∧和∨型单模激光系统，获得了在受不同原子衰减常数、不同原子─场耦合常数和能级非简并等三种因素影响时，∧型系统呈现无反转激光和∨型系统呈现无激光反转的条件；揭示了∧和∨型单模激光中不同原子衰减常数和能级非简并导致的双光子过程。     

各向异性n维耦合谐振子能量本征值的代数解法

耦合谐振子是量子光学中的重要研究问题之一,原因是许多实际物理问题的解决都依赖于耦合谐振子的模型,因此研究耦合谐振子求解的简便方法显得十分必要。本文运用数学上二次型正交化理论构造了一个形式上的变换矩阵,使既有坐标耦合又有动量耦合的各向异性n维耦合谐振子的Hamilton量对角化,求出了其本征值。并应用此方法求解了三维耦合谐振子的本征值,验证了该方法的正确性。由于该方法不需要求出变换矩阵的具体形式,使得运用此方法求解具有对称形式的Hamilton量的本征值问题变得简单、易计算出结果,该方法更具有普遍性,是一种十分有效的代数方法。     

用线性量子变换对角化二次型哈密顿量

借助线性量子变换(LQT)理论,对n模玻色和费米子的二次型哈密顿量,我们给出了简洁的对角化形式.并且指出,对于n模玻色子耦合二次型哈密顿量,通过一个负幺正矩阵(它是复辛群SP(2n,c)的元素)可以把它对角化;对n模费米子耦合二次型哈密顿量,通过一个幺正矩阵(它是复费米群F(2n,c)的元素)可以把它对角化.     

一种新的SOI波导拉曼激光器模型及其应用

通过考虑腔中的自发拉曼散射,提出一种新的绝缘体上硅(SOI)波导拉曼激光器物理模型。仿真结果表明该模型能较好地描述其小信号输出特性,实现对该类激光器的快速分析、设计与优化。利用模型对基于多种SOI波导的拉曼激光器进行分析,结果表明室温下只有采用拥有较大拉曼系数,较小线性损耗和较短的有效载流子寿命的SOI波导才能使拉曼激光器达到阈值。提出采用优化SOI波导截面几何尺寸的方法来降低有效载流子寿命,进而提高整体拉曼增益。结果显示该方法可大幅提高SOI波导拉曼激光器的输出功率和能量转换效率。     

A Hamiltonian formulation for coupled-wave equations

We construct a Hamiltonian formulation for coupled-wave equations that describes the envelope functions of the electric field in an almost-periodic distributed-feedback waveguide with gain or loss. From the Hamiltonian, we can derive that the determinant of the fundamental matrix of the waveguide is always unity. A perturbation formula for the eigenvalues of the coupled-wave equations is simply derived using the Hamiltonian formulation. The Hamiltonian also provides the basis for the numerical calculation of the eigenvalues using the variational method     

Efficient formulation of Raman amplifier propagation equations with average power analysis

For the first time, we derive efficient modeling equations for the average power analysis of Raman amplifiers (RAs) from the standard propagation equations. Applications of these equations to the numerical analysis of practical RA-based systems show a reduction in computation time of over two orders of magnitude compared with the direct integration approach based on ordinary coupled differential equations, while reproducing all the essential system performances precisely. In addition to enhanced computational efficiency, the derived equations also give deeper insights into the detailed dynamics of RAs.     

产生自聚焦的机制的理论分析

本文利用Ｈｅｍｐｔｉｎｎｅ提出的光和物质相互作用的热力学模型以及不可逆热力学原理，讨论了强电磁波（激光）在各向同性介质中产生的非线性现象－自聚焦，结果发现，自聚焦产生于场的相干驱动扩散和耦合热效应（吸收介质）。另外考虑到物质扩散的耦合效应，得出温度梯度对相驱动扩散产生的自聚焦存在削弱的倾向。     

Analytical model for Raman noise figure in dispersion-managed fibers

We derive an exact and a closed-form approximate analytic formula for effective lumped Raman noise figure in backward-pumped dispersion-managed fibers (DMFs) of arbitrary topology. Within the single-pump small-signal amplification model, important effects such as unequal loss coefficients at pump and signal wavelengths or splice loss for the pump and the signal between the DMFs' sections are taken into account. Theoretical results agree well with the noise figure measured in a symmetric DMF. The developed approach can be used to optimize the noise performance of DMFs.     

An Inverse-Kinematics Table-Based Solution of a Humanoid Robot Finger With Nonlinearly Coupled Joints

This paper presents a novel approach toward the inverse kinematics solution of the humanoid robot fingers with nonlinearly coupled joints, a challenging problem existing for years. Under an assumption that the coupled joint angles of the finger are the same, we first derive an approximate closed-form solution of the finger's inverse kinematics. Then, utilizing the approximate solution as the ancillary variable, we propose to solve the finger joint angles from this approximate solution rather than the fingertip position. Through analyzing properties of the approximate solution, it can be known that the coupled joint angles in the approximate solution play the most important role in the derivation of inverse kinematics. In practical implementation, a 1-D lookup table and the linear interpolation to the approximate solution are used to calculate the accurate joint angles. Simulation and experimental results demonstrate effectiveness of the proposed inverse kinematics method.     

Evaluation of Raman gain coefficient distribution independent of imperfection contributions

We have previously reported a technique for measuring the distribution of the Raman gain characteristics in optical fibers. It is well known that Raman gain characteristics are affected by dopants and the effective areas in optical fibers. The Raman gain coefficient independent of the influence of effective areas will be used to investigate the longitudinal uniformity in fibers. This letter describes a method for evaluating the Raman gain coefficient distribution in a way that distinguishes it from the effects of waveguide imperfections by employing our previously reported technique. Using this method, we performed experiments on various types of fiber, and confirmed that the Raman gain coefficient can be accurately measured.     

Closed Integral form expansion of Raman equation for efficient gain optimization Process

In this study, we introduce a closed integral form of coupled Raman equation set, which enables us to reduce the complex multipump Raman gain design problem into a series of matrix calculations. With simultaneous implementation of signal stimulated Raman scattering effect and Raman integration in single iteration step, fast convergence with excellent accuracy has been achieved.