Heat Kernel on Analytic Subvariety

In this paper, the author extends Peter Li and Tian Gang’s results on the heat kernel from projective varieties to analytic varieties. The author gets an upper bound of the heat kernel on analytic varieties and proves several properties. Moreover, the results are extended to vector bundles. The author also gets an upper bound of the heat operators of some Schr¨ondinger type operators on vector bundles. As a corollary, an upper bound of the trace of the heat operators is obtained.     

非线性增益介质中强激光热像的演化规律

高功率激光系统中的热像效应可能导致光束的峰值功率剧烈增加,增益非线性介质会使这种光强增幅更为强烈。基于菲涅尔-基尔霍夫衍射理论和非线性近轴波动方程,对强激光在增益克尔介质工作在饱和区时的热像产生过程进行理论分析,将光束传输方程中增益饱和部分进行麦克劳林展开,取其近似,经过推导得出了介质薄近似时热像强度解析式和热像位置。通过数值模拟对解析结论预测的热像强度和位置进行验证。仿真结果表明,热像的位置在衍射物相对于介质对称处,热像强度解析结果与模拟结果相符,在薄介质时,解析解与模拟结果拟合较好。热像强度随非线性介质内非线性效应增强而停止增加,此外,讨论了热像强度随调制类型的变化。     

布洛赫电子的拓扑与几何

文章回顾了电子的拓扑几何理论发展的初期,大约二十多年的历史。首先介绍拓扑陈数在凝聚态物理中的两个重要应用。其一关于量子霍尔效应,绝缘条件下霍尔电导可以写成一个陈数拓扑不变量,从而解释实验结果的精确量子化。其二关于绝热泵浦,它描述布洛赫能带的绝热电流响应,与电子极化有密切联系。拓扑陈数是布里渊区上贝里曲率的积分,后者本身也有独立的物理意义。接着介绍贝里曲率对电子动力学的影响,包括反常速度和轨道磁化等概念。作者还将这个理论推广到多带情况,使其可以应用到自旋输运等现象。最后,文中展示了再量子化方法,从半经典模型来获得布洛赫电子的有效量子理论。在非相对论极限下,泡利—薛定谔方程可以看作是狄拉克电子在正能谱上的等效量子理论,其中的自旋轨道耦合即是一种几何物理效应。     

Periodic solutions of nonlinear Schro^edinger type equations

By using the solutions of an auxiliary elliptic equation, a direct algebraic method is proposed to construct the exact solutions of nonlinear Schrfdinger type equations. It is shown that many exact periodic solutions of some nonlinear Schro^edinger type equations are explicitly obtained with the aid of symbolic computation, including corresponding envelope solitary and shock wave solutions.     

Sharp conditions of global existence for the quasilinear Schrödinger equation

The paper discusses a class of quasilinear Schrödinger equations describing the upper-hybrid oscillation propagation. By establishing a cross-constrained variational problem and a so-called invariant flow, we obtain a sharp condition for blow-up and global existence of solutions of the Cauchy problem.     

Quantized Riemann surfaces and semiclassical spectral series for a non-self-adjoint Schrödinger operator with periodic coefficients

We consider a non-self-adjoint Schrödinger operator describing the motion of a particle in a one-dimensional space with an analytic potential iV (x) that is periodic with a real period T and is purely imaginary on the real axis. We study the spectrum of this operator in the semiclassical limit and show that the points of its spectrum asymptotically belong to the so-called spectral graph. We construct the spectral graph and evaluate the asymptotic form of the spectrum. A Riemann surface of the particle energy-conservation equation can be constructed in the phase space. We show that both the spectral graph and the asymptotic form of the spectrum can be evaluated in terms of integrals of the pdx form (where x ∈31 ?/T? and p ∈, ? are the particle coordinate and momentum) taken along basis cycles on this Riemann surface. We use the technique of Stokes lines to construct the asymptotic form of the spectrum.     

Semiclassical spectral series of the Schrödinger operator on surfaces in magnetic fields

We consider the spectral problem for the Schrödinger operator describing a charged particle confined by a homogeneous magnetic field to a certain two-dimensional symmetric surface. Spectral asymptotic series are calculated for either strong or weak magnetic field.     

L p-estimates for Schr?dinger operators

L ^p-estimates of the resolvent for a large class of Schr?dinger operators are proved. Combining this with the almost analytic continuations, we obtainL ^p-estimates for functions of Schr?dinger operators.     

也谈含时Schrodinger方程的求解方法

利用算符对易关系的相似性和规范变换统一求解一些合时Ｓｃｈｒｄｉｎｇｅｒ方程．     

The number of energy levels of a particle in a uniform MQW structure

A recently obtained multilayer equation that gives the eigenvalues of the energy of a quantum particle in an arbitrary one-dimensional piecewise constant potential field is studied. In particular, this equation can be used to calculate the eigenvalues of the particle’s energy in an MQW structure, in which the potential takes only two different values in the various layers. A formula is analyzed that was obtained earlier by the author for the number of energy levels in a uniform MQW structure, i.e., in a structure with potential wells and walls of constant widths. The equation is substantiated for all uniform MQW structures. It is proved that the number of energy levels in a uniform MQW structure increases indefinitely with unlimited growth of the number of potential wells. The existence of uniform MQW structures with an arbitrarily large prescribed number of potential wells and with a single energy level is proved.