Exact periodic wave and soliton solutions in two-component Bose-Einstein condensates

We present several families of exact solutions to a system of coupled nonlinear Schrodinger equations. The model describes a binary mixture of two Bose-Einstein condensates in a magnetic trap potential. Using a mapping deformation method, we find exact periodic wave and soliton solutions, including bright and dark soliton pairs.

Exact parametric representations of orbits defined by cubic Hamiltonian

In this paper,we show that for any given planar cubic algebraic curves defined by a quadratic Hamiltonian vector field,we can always have their exact explicit parametric representations. We use a model of micro-structured solid to show an application of our conclusions.

An Analysis of Modified Emden-Type Equation ẍ+ αxẋ+ βx³= 0: Exact Explicit Analytical Solution, Lagrangian, Hamiltonian for Arbitrary Values of α and β

The modified Emden-type is being investigated by mathematicians as well as physicists for about a century. However, there exist no exact explicit solution of this equation, ẍ+ αxẋ+ βx3 = 0 for arbitrary values of α and β. In this work, the exact analytical explicit solution of modified Emden-type (MEE) equation is derived for arbitrary values of α and β. The Lagrangian and Hamiltonian of MEE are also worked out. The solution is also utilized to find exact explicit analytical solution of Force-free Duffing oscillator-type equation. And exact explicit analytical solution of two-dimensional Lotka-Volterra System is also worked out.

A Class of Quasi-exact Solutions of Rabi Hamiltonian

A class of quasi-exact solutions of the Rabi Hamiltonian,which describes a two-level atom interacting witha single-mode radiation field via a dipole interaction without the rotating-wave approximation,are obtained by using awavefunction ansatz.Exact solutions for part of the spectrum are obtained when the atom-field coupling strength and thefield frequency satisfy certain relations.As an example,the lowest exact energy level and the corresponding atom-fieldentanglement at the quasi-exactly solvable point are calculated and compared to results from the Jaynes-Cummings andcounter-rotating cases of the Rabi Hamiltonian.

Dressing Multiphoton Hamiltonian

The dressed Hamiltonian describing the multiphoton process is presented by means of a canonical transformation.The exact eigenvalues and eigenstates are given for any set of parameters ω_(0),ω and ε.The general evolution of this system is obtained.

势函数V(r)=A_1r^(-6)+A_2r^(-4)+A_3r^2的Hamiltonian本征方程的精确解

本文采用连分法得到相互作用势为V(r)=A1r-6 +A2r-4 +A3r2 的Hamiltonian算子的精确的能量本征值和能量本征函数.

An Exact Propagator for Solving the Triatomic Reactive Schrodinger Equation

The exact short time propagator, in a form similar to the Crank-Nicholson method but in the spirit of spectrally transformed Hamiltonian, was proposed to solve the triatomic reactive time-dependent schrodinger equation. This new propagator is exact and unconditionally convergent for calculating reactive scattering processes with large time step sizes. In order to improve the computational efficiency, the spectral difference method was applied. This resulted the Hamiltonian with elements confined in a narrow diagonal band. In contrast to our previous theoretical work, the discrete variable representation was applied and resulted in full Hamiltonian matrix. As examples, the collision energy-dependent probability of the triatomic H＋H2 and O＋O2 reaction are calculated. The numerical results demonstrate that this new propagator is numerically accurate and capable of propagating the wave packet with large time steps. However, the efficiency and accuracy of this new propagator strongly depend on the mathematical method for solving the involved linear equations and the choice of preconditioner.

Exactly Solved Anderson Lattice Model

A solvable Anderson lattice model is formulated.The exact eigenstates of model Hamiltonian are constructed by using the Bethe ansatz.The Be the ansatz equations are obtained from the periodic boundary conditions.

量子近似优化算法在精确覆盖问题中的应用

精确覆盖问题属于组合优化中的NP完全问题,使用经典算法难以在多项式时间范围内求解。为解决该问题,在开源量子计算框架qiskit上,提出基于量子近似优化算法(QAOA)的量子线路求解方案,并采用基于单纯形法的线性近似约束优化(COBYLA)算法对量子逻辑门中的参数进行优化。首先,通过精确覆盖问题的数学模型建立经典伊辛模型;其次,利用量子理论中的旋转变量对经典伊辛模型进行量子化,再用泡利旋转算子代替旋转变量,得到量子伊辛模型和问题哈密顿量,提高QAOA寻找最优的速度;最后,以混合哈密顿量为生成元的酉变换和问题哈密顿量为生成元的酉变换乘积的累积,得到问题哈密顿量期望的表达式,并由此设计生成量子线路。另外,通过经典处理器对两个酉变换中的参数进行优化,调整问题哈密顿量的期望值,从而提高求解的概率。该线路在IBM的开源量子计算框架qiskit上进行仿真实验,实验结果表明,所提方案能够在多项式时间内以95.6%的概率获得问题的解,验证了所提量子线路能够以较高的概率求得精确覆盖问题的解。

耦合MRT方程的三哈密顿对偶系统

本文将三哈密顿方法应用于耦合Merola-Ragnisco-Tu方程,获得了新的离散可积系统,并求出了它的线性谱问题、双哈密顿结构以及Darboux-Backlund变换.进一步,利用DarbouxBacklund变换求出了对偶系统的精确解.

哈密顿振幅方程的新的精确解

利用双曲函数法求出了一个新的哈密顿振幅方程ux+utt+2σ|u|2-εuxt=0的新的精确解。

On the Cauchy problem and peakons of a two-component Novikov system

We study a two-component Novikov system,which is integrable and can be viewed as a twocomponent generalization of the Novikov equation with cubic nonlinearity.The primary goal of this paper is to understand how multi-component equations,nonlinear dispersive terms and other nonlinear terms affect the dispersive dynamics and the structure of the peaked solitons.We establish the local well-posedness of the Cauchy problem in Besov spaces B^s/p,r with 1 p,r+∞,s>max{1+1/p,3/2}and Sobolev spaces H^s(R)with s>3/2,and the method is based on the estimates for transport equations and new invariant properties of the system.Furthermore,the blow-up and wave-breaking phenomena of solutions to the Cauchy problem are studied.A blow-up criterion on solutions of the Cauchy problem is demonstrated.In addition,we show that this system admits single-peaked solitons and multi-peaked solitons on the whole line,and the single-peaked solitons on the circle,which are the weak solutions in both senses of the usual weak form and the weak Lax-pair form of the system.

多分量退化的CH型方程的可积性及其解（英文）

主要研究多分量退化的含有立方项的CH型方程,并证明了其可积性:Lax表示,双哈密顿结构,以及递推算子.特别地,得到了一个退化的两分量的Novikov方程,并给出了其有限个拐点的奇性解.

A Hierarchy of Nonlinear Lattice Soliton Equations and Its Darboux Transformation

A hierarchy of nonlinear lattice soliton equations is derived from a new discrete spectral problem. The Hamiltonian structure of the resulting hierarchy is constructed by using a trace identity formula. Moreover, a Darboux transformation is established with the help of gauge transformations of Lax pairs for the typical lattice soliton equations. The exact solutions are given by applying the Darboux transformation.

Fracture analysis of magnetoelectroelastic bimaterials with imperfect interfaces by symplectic expansion

A Hamiltonian-based analytical method is used to study the mode Ⅲ interface cracks in magnetoelectroelastic bimaterials with an imperfect interface. By introducing an unknown vector, the governing equations are reformulated in sets of first-order ordinary differential equations. Using separation of variables, eigensolutions in the symplectic space are obtained. An exact solution of the unknown vector is obtained and expressed in terms of symplectic eigensolutions. Singularities of mechanical, electric, and magnetic fields are evaluated with the generalized intensity factors. Comparisons are made to verify accuracy and stability of the proposed method. Numerical examples including mixed boundary conditions are given.

Conformal structure-preserving method for damped nonlinear Schrdinger equation

In this paper,we propose a conformal momentum-preserving method to solve a damped nonlinear Schrodinger（DNLS） equation.Based on its damped multi-symplectic formulation,the DNLS system can be split into a Hamiltonian part and a dissipative part.For the Hamiltonian part,the average vector field（AVF） method and implicit midpoint method are employed in spatial and temporal discretizations,respectively.For the dissipative part,we can solve it exactly.The proposed method conserves the conformal momentum conservation law in any local time-space region.With periodic boundary conditions,this method also preserves the total conformal momentum and the dissipation rate of momentum exactly.Numerical experiments are presented to demonstrate the conservative properties of the proposed method.

Block(or Hamiltonian) Lie Symmetry of Dispersionless D-Type Drinfeld–Sokolov Hierarchy

In this paper, the dispersionless D-type Drinfeld–Sokolov hierarchy, i.e. a reduction of the dispersionless two-component BKP hierarchy, is studied. The additional symmetry flows of this hierarchy are presented. These flows form an infinite-dimensional Lie algebra of Block type as well as a Lie algebra of Hamiltonian type.

Generations of Integrable Hierarchies and Exact Solutions of Related Evolution Equations with Variable Coefficients

We first propose a way for generating Lie algebras from which we get a few kinds of reduced 6 6 Lie algebras, denoted by R6, R8 and R1,R6/2, respectively. As for applications of some of them, a Lax pair is introduced by using the Lie algebra R6 whose compatibility gives rise to an integrable hierarchy with 4- potential functions and two arbitrary parameters whose corresponding Hamiltonian structure is obtained by the variational identity. Then we make use of the Lie algebra R6 to deduce a nonlinear integrable coupling hierarchy of the mKdV equation whose Hamiltonian structure is also obtained. Again,via using the Lie algebra R62, we introduce a Lax pair and work out a linear integrable coupling hierarchy of the mKdV equation whose Hamiltonian structure is obtained. Finally, we get some reduced linear and nonlinear equations with variable coefficients and work out the elliptic coordinate solutions, exact traveling wave solutions, respectively.

Yb、YbO电子激发态的相对论含时密度泛函理论研究

本文用基于精确二分量哈密顿(exact two-component Hamiltonian)的相对论含时密度泛函理论(time-dependent relativistic density functional theory)计算了Yb和YbO的电子激发态,并利用对称性、自然原子轨道对激发态性质和归属进行了详细分析,所得结果支持实验对YbO基态与激发态的指认.

Time-dependent relativistic density functional study of Yb and YbO

The low-lying electronic states of Yb and YbO are investigated by using time-dependent relativistic density functional theory,which is based on the newly developed exact two-component Hamiltonian resulting from symmetrized elimination of the small component.The nature of the excited states is analyzed by using the full molecular symmetry.The calculated results support the previous experimental assignment of the ground and excited states of YbO.