多层共轴空心超导圆柱体(NSC)系统的GL泛函和磁通量子化

本文将N层共轴空心超导圆柱体系统作为一个整体而建立了Ginzburg-Landau(GL)泛函。在薄壁近似或弱磁场情况下求解GL电流方程。引入与含超导序参量的穿透深度和等效面积有关的类电感系数,给出了NSC系统类磁通量子化的具体表示式,它由N个磁通量子数n_1,n_2,…,n_N来表征,并在N=1,2时分别过渡到与单层和双层空心超导圆柱体(SSC和DSC)系统的类磁通量子化情形相一致的结果。     

电流激励下两带单结超导环的电磁性质研究

在两带Ginzburg-Landau理论基础上,我们研究了在电流激励情形下两带单结超导环的电磁性质.两带超导环中可引入的两个超导序参量的相位差满足sine-Gordon方程,由该方程的孤立子解我们得到了单个超导结(微桥结构)两端相位差与总磁通之间的线性关系.通过微桥中电流与超导结两端相位差满足的非线性Josephson方程,建立了在电流激励下环内磁通与外加电流之间的依赖关系.我们的分析表明两带超导环中可能产生的孤立子解及分数磁通量子化现象可以通过测量单结超导环中的电磁性质加以验证.     

超导量子干涉器件

超导现象是一种宏观量子现象.磁通量子化和约瑟夫森效应是两个最能体现这种宏观量子特性的物理现象.超导量子干涉器件(superconducting quantum interference device,SQUID)是利用这两个特性而形成的超导器件.SQUID器件在磁信号灵敏探测方面具有广泛的应用.本文简要介绍低温超导和高温超导SQUID器件的相关背景和发展现状以及应用领域.     

磁通量子比特qubit信号强度随势垒偏置电压的变化

在20mK极低温下,测量了超导磁通量子比特的环流方向,并测到量子比特(qubit)信号.通过改变磁通量子比特的势垒高度,得到qubit信号强度随势垒高度的变化的实验数据并建立理论模型解释了实验现象.     

非Abel Chern-Simons理论中量子水平的分数自旋性质

与经典水平下的研究不同，研究了（2＋1）维含非Abel Chern-Simons 项的非线性σ模 型量子水平的分数自旋性质.根据约束Hamilton系统的Faddeev-Senjanovic(FS)路径积分量 子化方案,对该系统进行量子化，由量子Noether定理给出了量子守恒角动量，说明了在量子 水平上该系统仍具有分数自旋的性质. 关键词： 约束Hamilton系统 分数自旋 O(3)非线性σ模型     

关于磁单极子通过超导线圈的再讨论

看过贵刊的《关于磁单极子通过超导线圈的讨论》[1](以下简称原文)一文,笔者认为原文至少有2处地方值得商榷.一是超导线圈中的电流I正比于Φ,与普通导体中电流正比于(dΦ/dt)不同.因为超导线圈的特性之一是线圈中的磁通量是不能变的.当有外来的磁通量Φ穿过超导线圈时,线圈中产生电流,电流产生的磁     

超导线圈中的感应电流

通过和普通导体线圈比较,从超导线圈内磁通量保持不变的性质出发,讨论了不同情况下超导线圈中感应电流的大小、方向和持续时间等方面的特点.     

超导弱磁场测量技术在磁法找油中的应用

简述了磁法找油的思路，指出了在航磁测量中使用高Ｔｃ超导磁强计的必要性。采用费曼提出的简化方法，计算了通过双结超导环的最大零电压电流Ｉｍ，计算结果表明Ｉｍ随通过环平面的磁通量作周期性变化，周期为一个磁通量子，根据计算结果，简要说明了超导磁强计的工作原理。最后，简要介绍了高Ｔｃ　ｄｃ　ＳＱＵＩＤ的研究进展。     

Jackiw-Pi模型的新涡旋解

运用φ映射拓扑流理论研究了Jackiw-Pi模型中的自对偶方程，得到一个静态的自对偶解满足带有δ函数项的刘维尔方程, 从而得到了一个完整的带有拓扑信息的涡旋解,自然给出了磁通量子化.     

超导数字计算机

超导数字计算机是下世纪超级机的发展方向 ,它在计算机科学发展的历史上将具有十分重要的意义,文章简要介绍了快速单磁通量子（ＲＳＦＱ）超导计算机研究的发展、ＲＳＦＱ逻辑电路的基本原理、超导计算机的基本结构以及超导数字计算机的展望。     

Some electromagnetic consequences of a geometric unified theory of gravitation and electromagnetism

The geometrical unified theory of gravitation and electromagnetism discussed in previous publications requires that electromagnetism be represented by an SU(2) subgroup. Electric matter should correspond to irreducible representations of the structure group, SL(4,), induced from its compact subgroup, rotation SU(2)x electromagnetic SU(2). Results predict the quantization of electric charge, magnetic flux and angular momentum without requiring magnetic monopoles. Unexpectedly, the necessary quanta of charge and flux imply fractional quantization of transverse resistance, under certain conditions (Fractional Quantum Hall Effect).     

Rotational symmetry of classical orbits, arbitrary quantization of angular momentum and the role of the gauge field in two-dimensional space

We study quantum–classical correspondence in terms of the coherent wave functions of a charged particle in two- dimensional central-scalar potentials as well as the gauge field of a magnetic flux in the sense that the probability clouds of wave functions are well localized on classical orbits. For both closed and open classical orbits, the non-integer angular-momentum quantization with the level space of angular momentum being greater or less than is determined uniquely by the same rotational symmetry of classical orbits and probability clouds of coherent wave functions, which is not necessarily 2π-periodic. The gauge potential of a magnetic flux impenetrable to the particle cannot change the quantization rule but is able to shift the spectrum of canonical angular momentum by a flux-dependent value, which results in a common topological phase for all wave functions in the given model. The well-known quantum mechanical anyon model becomes a special case of the arbitrary quantization, where the classical orbits are 2π-periodic.     

Calculation of gluon contribution to the proton spin by using the non-perturbative quantization à la Heisenberg

The contribution of crossed gluon fields in flux tubes connecting quarks to the proton spin is calculated. The calculations are performed following non-perturbative Heisenberg’s quantization technique. In our approach a proton is considered as consisting of three quarks connected by three flux tubes. The flux tubes contain colour longitudinal electric and transversal electric and magnetic fields. The transversal fields causes the appearance of the angular momentum density. The dimensionless relation between the angular momentum and the mass of the gluon fields is obtained. The contribution to proton spin from rotating quarks and flux tubes connecting quarks is estimated. Simple numerical relation between the proton mass, the speed of light and the proton radius, which is of the same order as the Planck constant, is discussed.     

Quantized Magnetic Flux in the Bohr–Sommerfeld Model

Based on the Bohr–Sommerfeld model, we investigate the quantization of magnetic flux through the electronic orbits together with its dependence on additional sources of magnetic fields. The additional magnetic field causes changes of the angular momentum and hence shifts of the energy of the atomic levels. We study this effect for the cases of the Zeeman effect, where the source is an external homogeneous magnetic field, and the hyperfine interaction, where the source is the field of the magnetic moment of the nucleus. We discuss a model for the handling of the different angular momentum contributions for which the energy shifts due to the Zeeman effect and the magnetic dipole contribution to the hyperfine interaction can be reproduced quite well. The meaning of “spin,” however, changes within this approach drastically. The unusual Landé g-factor of the electron is discussed to be the result of a reduced ground-state angular momentum of the electron in combination with the field of the magnetic moment of the electron rather than an intrinsic property of the electron.     

Induced fractional zero-point angular momentum for charged particles of the Bohm–Aharonov system by means of a “spectator” magnetic field

An induced fractional zero-point angular momentum of charged particles by the Bohm–Aharonov (BA) vector potential is realized via a modified combined trap. It explores a “spectator” mechanism in this type of quantum effects: In the limit of the kinetic energy approaching one of its eigenvalues the BA vector potential alone cannot induce a fractional zero-point angular momentum at quantum mechanical level in the BA magnetic field-free region; But when there is a “spectator” magnetic field the BA vector potential induces a fractional zero-point angular momentum. The “spectator” does not contribute to such a fractional angular momentum, but plays essential role in guaranteeing non-trivial dynamics at quantum mechanical level in the required limit. This “spectator” mechanism is significant in investigating the BA effects and related topics in both aspects of theory and experiment.     

Induced vacuum quantum numbers in 2 + 1 dimensions

We calculate the induced vacuum fermionic charge and angular momentum in 2 + 1 dimensions around an abelian magnetic flux tube configuration, using a space compactification technique. It is found that the charge and the total angular momentum are topological invariants and depend on the total magnetic flux, while the fermionic angular momentum depends on the local features of the gauge field configuration and vanishes in the limit of a tube with diameter large compared with the Compton wavelength of the fermions.     

Optimal rotations of deformable bodies and orbits in magnetic fields

Deformations can induce rotation with zero angular momentum where dissipation is a natural "cost function." This gives rise to an optimization problem of finding the most effective rotation with zero angular momentum. For certain plastic and viscous media in two dimensions the optimal path is the orbit of a charged particle on a surface of constant negative curvature with a magnetic field whose total flux is half a quantum unit.     

The Aharonov-Bohm effect: Why it cannot be eliminated from quantum mechanics

The Aharonov-Bohm effect is a necessary and easily understood feature of conventional quantum mechanics. Attempts to remove it from the theory must involve a drastic change in our understanding of the quantization and conservation of angular momentum, or of the role of the classical equations of motion in quantum mechanics. The key point is that a charged particle is the source of an electric field which will penetrate a magnetic field from which the particle is excluded. The crossed fields contain angular momentum whose existence alters the motion of the particle because the total angular momentum is quantized.     

含Hopf项和Maxwell-Chern-Simons项O(3)非线性σ模型的分数自旋和分数统计性质

研究了（2＋1）维时空中含Hopf项和Maxwell-Chern-Simons(MCS)项的非线性σ模型的分数自旋性质.根据约束Hamilton系统的Faddeev-Senjanovic(FS)路径积分量子化方案,对该系统进行量子化，由量子Noether定理给出了量子守恒角动量，说明了在量子水平上该系统仍具有分数自旋的性质. 关键词： 约束Hamilton系统 分数自旋 O(3)σ模型