具有格点各向异性的一维铁磁链中的量子孤子和内禀局域模(英文)

基于Hartree-Fock方法和多标度方法,我们考察了具有格点各向异性的一维铁磁链中的量子孤子和内禀局域模,量子磁振子的波函数由量子包络孤子来描述.在布里渊区边界,量子包络孤子变成了量子内禀局域模,它的量子本征频率在简谐波带的顶部上方,量子磁振子主要集中在中心位置j=j0的附近.     

Quantum Solitons and Localized Modes in a One-Dimensional Lattice Chain with Nonlinear Substrate Potential

In the classical lattice theory, solitons and localized modes can exist in many one-dimensional nonlinear lattice chains, however, in the quantum lattice theory, whether quantum solitons and localized modes can exist or not in the one-dimensional lattice chains is an interesting problem. By using the number state method and the Hartree approximation combined with the method of multiple scales, we investigate quantum solitons and localized modes in a one-dimensional lattice chain with the nonlinear substrate potential. It is shown that quantum solitons do exist in this nonlinear lattice chain, and at the boundary of the phonon Brillouin zone, quantum solitons become quantum localized modes, phonons are pinned to the lattice of the vicinity at the central position j=j₀.     

在一维均匀铁磁链中磁振动的内禀局域模

利用多标度方法和准离散近似,我们考察了在一维均匀铁磁链中磁振动的内禀局域模; 结果表明磁振动的内禀局域模在许多方面都与晶格振动的内禀局域模相类似;它们是近邻自旋之间非线性相互作用的结果.这种内禀局域模的存在并没有破坏系统的平移对称性,它们能在任何晶格位被激发.它们的量子本征频率在简谐磁振动频带的上方.     

Intrinsic localized modes and nonlinear impurity modes in curved Fermi-Pasta-Ulam chain

We explore the nature of intrinsic localized modes (ILMs) in a curved Fermi-Pasta-Ulam (FPU) chain and the effects of geometry and second-neighbor interaction on the localization and movability properties of such modes. We determine analytically the structure of the localized modes induced by an isotopic light-mass impurity in this chain. We further demonstrate that a nonlinear impurity mode may be treated as a bound state of an ILM with the impurity.      

Bright and dark small amplitude nonlinear localized modes in a quantum one-dimensional Klein--Gordon chain

By means of the Glauber＇s coherent state method combined with multiple-scale method, this paper investigates the localized modes in a quantum one-dimensional Klein-Gordon chain and finds that the equation of motion of annihilation operator is reduced to the nonlinear Schroedinger equation. Interestingly, the model can support both bright and dark small amplitude travelling and non-travelling nonlinear localized modes in different parameter spaces.     

一维反铁磁链中双亚格点模型的孤子解(英文)

求出了一维反铁磁链中双亚格点模型的孤子解,并求出了孤子宽度、峰值、静止能量和有效质量.在al=bl 和al=-bl 两种情况下求方程的精确解.     

单离子各向异性影响下的一维铁磁链中的孤子

利用行波解法，研究了考虑交换各向异性和单离子各向异性的一维铁磁链，得出椭圆函数波解和孤子解,并讨论了单离子各向异性对椭圆函数波和孤子的影响.研究表明：单离子各向异性对一维铁磁链中椭圆函数波和孤子的激发及其稳定性有显著影响.单离子各向异性不利于易轴铁磁链中椭圆函数波和孤子解的激发，但有利于它们的稳定；而在易平面铁磁链中，单离子各向异性使椭圆函数波和孤子激发变得容易，但不利于它们的稳定.此外，还讨论了单离子各向异性对一维各向同性铁磁链中的孤子激发具有的影响. 关键词： 各向异性 单离子各向异性 孤子 铁磁链     

扰动对一维局域模的影响

在紧束缚模型基础上，考虑到缺陷、温度、掺杂等外界因素的影响，用方形随机分布模拟了格点原子扰动对一维局域模的影响.给出了不同扰动参数σ下，孤子和极化子中各个局域模的变化情况.计算发现，由于孤子g₁模的钉扎效应，扰动后，弱模g₄定域性会得到加强，还会产生两个新定域模g′₁和g′₂，它们与相应的g₁和g₂模有相同的节点和宇称 ；极化子的g₇模在畸变较大时将 关键词： 扰动 局域模 聚合物     

Intrinsic localized modes of a classical discrete anisotropic Heisenberg ferromagnetic spin chain

We report several exact intrinsic localized mode solutions of the classical spin evolution equation of a one-dimensional anisotropic Heisenberg ferromagnetic spin chain in terms of Jacobian elliptic functions. These include one, two and three spin excitations. All these solutions have smooth anticontinuum limits. Their linear stability and semiclassical quantization are also discussed briefly.     

Controlled switching of intrinsic localized modes in a one-dimensional antiferromagnet

Nearly-steady-state locked intrinsic localized modes (ILMs) in the quasi-1D antiferromagnet (C(2)H(5)NH(3))(2)CuCl(4) are detected via four-wave mixing emission or the uniform mode absorption. Exploiting the long-time stability of these locked ILMs, repeatable nonlinear switching is observed by varying the sample temperature, and localized modes with various amplitudes are created by modulation of the microwave driver power. This steady-state ILM locking technique could be used to produce energy localization in other atomic lattices.     

Influence of nonlinear atomic interaction on excitation of intrinsic localized modes in carbon nanotubes

Excitation of intrinsic localized modes (ILMs) in carbon nanotubes (CNTs) with different chiral structures was investigated by molecular dynamics simulations. For CNTs with a chiral angle less than or equal to 30^°, energy concentration that continued for more than 200 fs was found in a localized area, where a pair of neighboring atoms strongly oscillated with a higher vibrational frequency than the upper bound of phonon bands. This evidently indicates excitation of the ILM. On the other hand, the ILM was not excited in CNTs with a chiral angle greater than or equal to 41^°. Analyzing the nonlinearity of the interaction between excited atoms in the ILM vibration mode, we elucidated that nonlinearity predominates the selective ILM excitation. Furthermore, stronger nonlinearity excites ILMs with both higher frequency and longer lifetime.     

An exact limit for the Peierls distortion energy in an antiferromagnetic chain by means of a renormalization procedure

A renormalization procedure gives a rigorous upper bound for the ground-state energy per spin for a Peierls-distorted antiferromagnetic chain with Heisenberg interaction.     

钉扎效应对聚噻吩中双空穴极化子附近局域振动模的影响

基于扩展的二维Su-Schrieffer-Heeger模型，研究了库仑钉扎作用对聚噻吩中双空穴极化子 附近的局域振动模的影响.除了与激发方式无关的本征振动模外，发现了与激发方式相关的 声子振动模式.计算结果与聚噻吩红外和拉曼光谱实验数据相当符合，从而对掺杂诱导和光 致激发下聚噻吩吸收光谱的区别给出了较好的理论阐释. 关键词： 聚噻吩 钉扎效应 吸收光谱 局域振动模     

一维高分子链中点缺陷引起的局域模

将聚苯胺等一类聚合物简化成一维复式线性链,讨论了这一类聚合物仅含一个点缺陷时的振动模.考虑到点缺陷附近弹性恢复力常数的变化,预期了局域模的出现,说明了模的局域化程度,包括模的频移及振动本征矢的分布情况与质量缺陷程度、力常数改变程度的关系.     

Entanglement of a two-qubit anisotropic Heisenberg XYZ chain in nonuniform magnetic fields with intrinsic decoherence

Taking the intrinsic decoherence effect into account, this paper investigates the entanglement of a two-qubit anisotropic Heisenberg XYZ model in the presence of nonuniform external magnetic fields by employing the concurrence as entanglement measure. It is found that both the intrinsic decoherence and the anisotropy of the system give a significant suppression to the entanglement. Moreover it finds that the initial state of the system plays an important role in the time evolution of the entanglement, which means that the entanglement of the system is independent of the nonuniformity and uniformity of the magnetic field when the system is in the initial state ｜ψ （0）） = ｜00） and [ψ′ （0）） = m ｜01） ＋ n ｜10）, respectively.     

一维双原子链中杂质引起的局域振动模

对含杂质的一维双原子链,在链中所有原子之间近邻相互作用力常数均相等的情况下,数值求解晶格振动的运动方程组,得到不同局域振动模的振动图像和产生条件,给出了局域模关于杂质原子质量和原胞中两种晶格原子质量比分布的相图．     

一维单原子链中杂质引起的局域振动模

讨论了一维单原子链中杂质引起的晶格局域振动模和局域振动图像,分析了杂质质量和杂质近邻力常数对振动模的影响,通过数值求解晶格振动运动方程组．给出了局域振动模关于杂质质量和杂质近邻力常数分布的相图;分析了含杂质晶格振动模频率相对于完整晶格振动模频率的变化。     

Effects of intrinsic decoherence on the entanglement of a two-qutrit 1D optical lattice chain with nonlinear coupling

We have investigated the intrinsic decoherence on the entanglement of a two-qutrit one-dimensional (1D) optical lattice chain with nonlinear coupling. As a measure of the entanglement, the negativity of the system is calculated. It is shown that the influence of intrinsic decoherence on the entanglement varies in different initial systems.     

一维分子链中激子与声子的相互作用和呼吸子解

运用连续极限近似，求解声子与激子相互作用的运动方程，得到了简谐分子链和 非简谐分子链中晶格振动的孤子解，在考虑三次非简谐势的情况下，一维分子链晶格振动具 有扭结孤子解，在考虑具有四次非简谐势的情况下，得到一维分子链晶格振动具有呼吸子解 . 关键词： 一维分子链 激子 声子 孤子 呼吸子 非线性效应