Λ-型三能级单原子的辐射谱

采用时间演化算符方法，研究腔内单模光场中Λ－型三能级单原子的辐射谱，给出了辐射谱一般公式，并讨论在粒子数纯态、相干态和热辐射三种光场激励下的辐射频谱结构。     

On the asymptotic positivity of solutions for the extended Fisher–Kolmogorov equation with nonlinear diffusion

The objective of this paper aims to prove positivity of solutions for a semilinear dissipative partial differential equation with non‐linear diffusion. The equation is a generalized model of the well‐known Fisher–Kolmogorov equation and represents a class of dissipative partial differential equations containing differential operators of higher order than the Laplacian. It arises in a variety of meaningful physical situations including gas flows, diffusion of an electron–ion plasma and the dynamics of biological populations whose mobility is density dependent. In all these situations, the solutions of the equation must be positive functions. Copyright © 2002 John Wiley & Sons, Ltd.     

双模光场与运动三能级原子作用系统的反聚束效应

采用求解Schrdinger方程和数值计算方法,研究了双模纠缠相干光场与运动V型三能级原子相互作用过程中的聚束和反聚束效应.结果表明:平均光子数变动不大,系统就会由聚束效应跃变为反聚束效应,关联程度最强;平均光子数取一定数值时,原子运动速度增大引起时间演化曲线显著上移,振荡周期变小,对系统的聚束和反聚束效应也有较强影响.当平均光子数较大时,原子初态和双模纠缠相干光场的纠缠度无任何影响;仅当平均光子数较小时,原子初态和双模纠缠相干光场的纠缠度变化引起曲线振荡幅度变化,位置发生小幅度移动,产生弱关联.     

Algebraic Approach to the Hulthen Potential

In this paper the energy eigenvalues and the corresponding eigenfunctions are calculated for Hulthen potential. Then we obtain the ladder operators and show that these operators satisfy SU(2) commutation relation.     

形变相干光场与级联型三能级原子相互作用中场的反聚束效应

建立了q形变光场与级联型三能级原子相互作用的非线性理论, 求得相互作用绘景中薛定谔方程的形式解及在其态下的期望值, 利用数值计算揭示了q形变对场与三能级原子相互作用中场反聚束效应的影响. 研究发现q偏离1的程度越大, q形变对场反聚束效应的调控能力越强, 反映出q形变的非线性行为对量子相干性的干扰以及对量子特性的影响. 当q→1时, 恢复为普通线性理论.     

B位Co掺杂对Sr14C24O41的结构和电输运的影响

采用固相反应法制备了系列Sr14（Cu1-xCox）24O41（x=0,0.02,0.06,0.1,0.14,0.18）的样品,X-射线衍射结果显示所有样品均为单相,且Co的掺杂几乎不改变样品的晶格常数,电子衍射和X-射线光电子能谱的测量结果证实Co替代的是链上的Cu原子;电输运的测量显示,Co掺杂样品表现为半导体行为,且渡越温度T随掺杂量的增加逐渐减小.     

Enhanced cooling of a V-type three-level atom in an optical cavity

We have studied theoretically and numerically the enhanced cooling of a V-type three-level atom in a high-finesse optical cavity and shown that the cooling rate can be increased by one order of magnitude over that of a two-level atom, and the momentum amplitude tends to a stationary state much smaller than that of a two-level atom. We have further shown that the cooling rate can be significantly improved by using feedback and a time-dependent pump.     

τ-Categories I: Ladders

In this series of papers, we introduce τ-categories, which are additive categories with some kind of Auslander–Reiten sequences. We apply them to study the category of lattices over orders. In this first paper, we study minimal projective resolutions in functor categories over τ-categories. Then we give a structure theorem of completely graded τ-categories using mesh categories. Presented by K. Roggenkamp Mathematics Subject Classifications (2000) primary 16G30; secondary 16E65, 16G70, 18E05. Osamu Iyama: Current address: Department of Mathematics, University of Hyogo, Himeji, 671-2201, Japan. e-mail: iyama@sci.u-hyogo.ac.jp.     

Thermal Analysis of Ladder Polymers Obtained From Multimonomers

Differential scanning calorimetry and thermogravimetry were used to examine the thermal behaviour of the multimonomers poly(2-methacryloyloxyethyl methacrylate) and poly(2-acryloyloxyethyl methacrylate), of the ladder polymers prepared by the template polymerization of these multimonomers, and of a linear analogue of the ladder polymers, poly(2-butyrylethyl methacrylate). The results obtained show that only one of the ladder polymers has a considerably higher thermal stability than that of their linear analogue. This revised version was published online in August 2006 with corrections to the Cover Date.