求解三模耦合谐振子精确能谱的一种方法

基于相空间中的幺正转动变换,利用有序算符内的积分技术,得到了相空间中转动算符、傅里叶变换算符和宇称算符的相干态表示.进而引入并利用相空间中的三模转动算符,简捷地实现了三模坐标-动量耦合谐振子哈密顿量的退耦合,给出了该耦合形式谐振子的精确能谱及其能量本征态.     

n模耦合谐振子量子系统的精确波函数

利用不变本征算符法研究了n模耦合谐振子量子系统的简正频率及其对应的简正坐标与共轭动量,并对系统的哈密顿量进行了退耦合,得到了系统的明显的简正频率解析解.推导出坐标表象中系统的精确波函数的解析解.并对不同情形的耦合系数进行了讨论,认识到n模动量耦合谐振子体系和n模坐标耦合谐振子体系是本文所研究的体系的特例.     

利用二次型求解n模耦合谐振子能量本征值精确解

利用二次型理论构造一个幺正矩阵进行坐标和动量变换,把n模动量耦合谐振子体系的哈密顿量化为标准的二次型,进而得到n模动量耦合谐振子体系的能量本征值.对n模坐标耦合的情况也进行了类似求解,并提供了解决该类问题的一般数学方法.     

利用表象变换精确求解最一般双耦合谐振子的能量本征值

将变换后的哈密顿量进一步变换到占有数表象,使哈密顿量对角化,精确求解出最一般双耦合谐振子,即哈密顿量中含非对角项(-λx1x2 vp1p2)的玻色谐振子的能量本征值．讨论了由耦合所引起的能级分裂。     

含时耦合谐振子体系的动力学演化

利用含时量子变换理论,给出含时双模耦合谐振子的严格解.并根据这一结果,对于给定的初态为Fock态和相干态情形,讨论了其动力学演化.     

含时二维双耦合各向异性谐振子的严格波函数

坐标与动量通过一个特殊的转动变换,成功完成哈密顿量的退耦合,进而采用尝试函数求得了质量和频率均不相等且均含时的双耦合二维谐振子的严格波函数.波函数的正确性在其普遍性讨论中得到印证.     

具有坐标和动量一阶耦合的两量子谐振子的演化

提出了具有坐标和动量一阶耦合的两量子谐振子的演化问题。通过引起适当的算符和辅助函数，求出了问题的精确解。     

具有q^4的两个耦合量子非谐振子的演化

在文献（５）的基础上，分析了两个耦合的量子非谐振子，并讨论了一种典型的实例，通过引进几个算符和辅助函数，求出了问题的精确解。     

二维耦合量子谐振子的本征值和本征函数

运用广义线性量子变换理论,给出一类二维耦合量子谐振子的能量本征值、本征函数、坐标和动量算符在能量表象中的矩阵元及演化算符.     

二模谐振子能谱研究

通过对非耦合谐振子系统能谱、非耦合与坐标耦合共同组成的谐振子系统能谱、非耦合与动量耦合共同组成的谐振子系统能谱、非耦合与坐标动量交叉耦合共同组成的谐振子系统能谱和非耦合与压缩项耦合共同组成的谐振子系统5种谐振子能谱进行求解时,通过分析比较发现:其一,对存在非对易参数的能级差的解时,当非对易参数为零时,所求的哈密顿量能级差的解与非耦合谐振子能谱能级差的解相似,从而验证了求解结果的正确性;其二表明了坐标耦合系数、动量耦合系数和压缩性系数都对共同组成的谐振子系统能谱的能级差产生了影响;其三,对非耦合与坐标动量交叉耦合共同组成的谐振子系统能谱而言,坐标动量交叉耦合系数和非对易参数都没有对交叉耦合谐振子的能级差产生任何影响.对多种耦合系统谐振子能谱进行求解,覆盖面广,分析全面.     

利用不变量本征算符求解二维耦合量子谐振子的能级间隔

目前不变量本征算符方法已成功地解决了某些量子系统哈密顿量能级问题.对于二维耦合量子谐振子,利用这一方法可以非常简捷有效地给出其能级信息,而不需要使其哈密顿量对角化.计算结果表明,不同耦合形式的二维耦合量子谐振子的能级间隔是不同的.     

Complex dynamics analysis of impulsively coupled Duffing oscillators with ring structure

Impulsively coupled systems are high-dimensional non-smooth systems that can exhibit rich and complex dynamics.This paper studies the complex dynamics of a non-smooth system which is unidirectionally impulsively coupled by three Duffing oscillators in a ring structure.By constructing a proper Poincare map of the non-smooth system,an analytical expression of the Jacobian matrix of Poincare map is given.Two-parameter Hopf bifurcation sets are obtained by combining the shooting method and the Runge-Kutta method.When the period is fixed and the coupling strength changes,the system undergoes stable,periodic,quasi-periodic,and hyper-chaotic solutions,etc.Floquet theory is used to study the stability of the periodic solutions of the system and their bifurcations.     

二次型方法求解坐标与动量耦合的n维谐振子能量本征值

借助于数学上的二次型理论,给出一种求解n维坐标与动量耦合的谐振子的普遍方法,并且运用该方法求出了二维和三维坐标与动量耦合的本征值.该方法给出的结论与其他方法相同,说明该方法的正确性,并且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哈密顿量的本征值问题变得简单,易计算出结果.该方法具有普遍性,...     

耦合分数阶混沌振荡器的主-从同步

近年来对分数阶系统的动力学研究得到了较为广泛的关注。本文研究了基于主-从耦合同步法的同步技术并实现了两个耦合的分数阶振荡器的混沌同步。仿真结果表明：在适当的耦合强度的调节下，该方法可实现两个耦合分数阶混沌振荡器的准确同步，且分数阶混沌振荡器的同步率明显慢于整数阶混沌振荡器的同步率；而耦合分数阶混沌振荡器在实现同步的过程中，随着阶数的提高，同步误差曲线变得平滑，这表明，系统阶数的提高改善了耦合混沌振荡器实现同步的平稳性。     

Analytical calculation of the transition to complete phase synchronization in coupled oscillators

Here we present a system of coupled phase oscillators with nearest neighbors coupling, which we study for different boundary conditions. We concentrate at the transition to the total synchronization. We are able to develop exact solutions for the value of the coupling parameter when the system becomes completely synchronized, for the case of periodic boundary conditions as well as for a chain with fixed ends. We compare the results with those calculated numerically.      

Entropy,information theory,and the approach to equilibrium of coupled harmonic oscillator systems

Finite segments of infinite chains of classical coupled harmonic oscillators are treated as models of thermodynamic systems in contact with a heat bath, i.e., canonical ensembles. The Liouville function for the infinite chain is reduced by integrating over the outside variables to a function _N of the variables of theN-particle segment that is the thermodynamic system. The reduced Liouville function _N which is calculated from the dynamics of the infinite chain and the statistical knowledge of the coordinates and momenta att = 0, is a time-dependent probability density in the 2N-dimensional phase space of the system. A Gibbs entropy defined in terms of _N measures the evolution of knowledge of the system (more accurately, the growth of missing pertinent information) in the sense of information theory. As ¦t ¦ , energy is equipartitioned, the entropy evolves to the value expected from equilibrium statistical mechanics, and _N evolves to an equilibrium distribution function. The simple chain exhibits diffusion in coordinate space, i.e., Brownian motion, and the diffusivity is shown to depend only on the initial distribution of momenta (not of coordinates) in the heat bath. The harmonically bound chain, in the limit of weak coupling, serves as an excellent model for the approach to equilibrium of a canonical ensemble of weakly interacting particles.     

Obtaining certificates for complete synchronisation of coupled oscillators

In this paper, we provide a novel reformulation of sufficient conditions that guarantee global complete synchronisation of coupled identical oscillators to make them computationally implementable. To this end, we use semidefinite programming techniques. For the first time, we can efficiently search for and obtain certificates for synchronisability and, additionally, also optimise associated cost functions. In this paper, a Lyapunov-like function (certificate) is used to certify that all trajectories of a networked system consisting of coupled dynamical systems will eventually converge towards a common one, which implies synchronisation. Moreover, we establish new conditions for complete synchronisation, which are based on the so called Bendixson’s Criterion for higher dimensional systems. This leads to major improvements on the lower bound of the coupling constant that guarantees global complete synchronisation. Importantly, the certificates are obtained by analysing the connection network and the model representing an individual system only. In order to illustrate the strength of our method we apply it to a system of coupled identical Lorenz oscillators and to coupled van der Pol oscillators.