一个描述Josephson振动阻尼效应的场方程

在GPE方程的基础上添加了一个耗散项-12γcψ,用来分析双势阱模型的Josephson振荡中的阻尼现象,并得出:凝聚态粒子总数及 Josephson振动的振幅随时间呈指数衰减.     

量子微结构中的Josephson效应

文章为纪念Josephson效应发现50周年而作.文章介绍了当前关于几种量子微结构中Josephson效应的理论研究,涉及Josephson效应的基本物理现象和它在某些热点材料中的独特表现,如单层石墨纳米条带中的0-π转变,二维拓扑绝缘体中的手征性边态超导电流,以及半导体微腔中激子极化激元凝聚体之间的Josephson效应和直流-交流Josephson电流的转变.     

对称双阱中玻色-爱因斯坦凝聚体的量子隧穿的临界态

在半经典理论框架下利用平均场和双模近似理论研究在弱相互作用、无衰减效应和无周期调制时,在对称双阱中在两个玻色-爱因斯坦凝聚体(BEC)之间初始相位差分别为0和π的情况下临界态时BEC的动力行为,并进行了相应分析.由于系统是保守系统,在临界态时原子不会象有衰减效应时一样自动停止振荡,而是会作永不停止的无规则振荡.原子振荡在Josephson振荡和自捕获振荡之间的临界态时既呈现Josephson振荡的特征,又呈现自捕获振荡的特征,而在π相位模式自捕获振荡和φ(O)=π的running phase模式自捕获振荡之间的临界态时既呈现π相位模式自捕获振荡的特征,又呈现φ(0)=π的running phase模式自捕获振荡的特征.     

全铌超导Josephson结的EWB仿真模型

通过超低温实验直接测量了制备的全铌Josephson结的电压源驱动RCSJ模型的I-V特性曲线。建立了Josephson结在电路仿真软件EWB中的模型,极大的方便了Josephson结及相关电路的仿真研究。利用这一新模型对Josephson结的基本特性进行了较为系统的研究,包括RSJ模型和RCSJ模型的直流驱动I-V特性曲线。     

二级微扰下小电容Josephson结的行为

本文采用 Stewart-McCumber 模型,用双变量微扰法在二级近似下对 Josephson 结的行为进行了讨论.计算指出,在结的 I-V 特性曲线上有二次谐波台阶和分谐台阶,井得出了     

超导Josephson结直流I-V特性的数值计算

为了研究超导Josephson结的性质,选用四阶龙格-库塔法对RSJ模型下单个Josephson结及其阵列以及微波辐照下Josephson结的直流I-V特性进行了数值计算,并将模拟结果与实验结果进行了比较.     

超导Josephson结直流Ⅰ-Ⅴ特性的数值计算

为了研究超导Josephson结的性质,选用四阶龙格-库塔法对RSJ模型下单个Josephson结及其阵列以及微波辐照下Josephson结的直流Ⅰ-Ⅴ特性进行了数值计算,并将模拟结果与实验结果进行了比较.     

超导Josephson结直流I—V特性的数值计算

为了研究超导Josephson结的性质，选用四阶龙格一库塔法对RSJ模型下单个Josephson结及其阵列以及微波辐照下Josephson结的直流I-V特性进行了数值计算，并将模拟结果与实验结果进行了比较．     

非平衡情况Josephson电流的Harris奇点

本文用OS模型研究了当组成Josephson隧道结的一个超导膜处于非平衡态时,Josephson电流的Harris奇点的变化。 关键词：     

直流和交流Josephson效应的研究

基于Feynman模型得到的Josephson方程,在求解过程中采取了ρ1=ρ2的假设,但这个假设在数学处理上并不严格。为了得到严格的结果,未进行上述假设,通过解微分方程得到了严格的Josephson方程,结果显示在一定条件下才能得到通常所说的Josephson方程。     

Critical current oscillations in S/F heterostructures in the presence of s–d scattering

Josephson current is investigated in the superconductor/ferromagnet/superconductor junction. It was shown that the current exhibited damping oscillations as a function of the ferromagnetic layer thickness. Previous theories based on Usadel or Eilenberger equations have predicted that the damping length and oscillation period divided by 2π were the same for weak ferromagnetic spacer. This contradicts past experiments. A new calculation of the Josephson current is proposed. The Gorkov equations are solved taking into account s–d scattering in ferromagnet. It is shown that the oscillation period depends only on the exchange magnetic field in the spacer, whereas the damping length is connected to the ferromagnetic mean free path. The concordance with the former experiment allows one to conclude that s–d scattering as a pair-breaking mechanism plays a significant role in the proximity effect in S/F heterostructures.     

Quantum coherence in a superfluid Josephson junction

We report a new kind of experiment in which we take an array of nanoscale apertures that form a superfluid (4)He Josephson junction and apply quantum phase gradients directly along the array. We observe collective coherent behaviors from aperture elements, leading to quantum interference. Connections to superconducting and Bose-Einstein condensate Josephson junctions as well as phase coherence among the superfluid aperture array are discussed.     

非对称的玻色-爱因斯坦凝聚中的约瑟夫森结的动力学性质

利用半经典量子理论，研究了玻色-爱因斯坦凝聚体处于非对称的约瑟夫森结的动力学行为.结果表明双势阱中不同势阱的基态能量差与其相互作用能量的比率χ=0时，凝聚体表现为约瑟夫森效应；当χ≠0时，凝聚体中既存在量子宏观隧穿效应，又存在量子宏观局域效应. 关键词： 玻色爱因斯坦凝聚 约瑟夫森结 动力学性质     

Finite-temperature phase-locking transition in three-dimensional arrays of Josephson coupled Bose–Einstein condensates

We consider theoretically a phase-locking transition in Bose–Einstein condensate in an optical lattice in the regime where system can realized as a three-dimensional Josephson junction array. The coherence between adjacent Bose condensates (trapped in the valleys of the periodic potential) caused by the Josephson tunneling can lead to a phase transition with a global phase coherence at certain critical temperature. Using a model Hamiltonian of Josephson weakly coupled Bose condensates we calculate the critical temperature for the three-dimensional system placed in a simple cubic lattice and discuss the result in the context of system parameters and possible experiments.     

Holographic Josephson junctions

We construct a gravitational dual of a Josephson junction. Calculations on the gravity side reproduce the standard relation between the current across the junction and the phase difference of the condensate. We also study the dependence of the maximum current on the temperature and size of the junction and reproduce familiar results.     

Quantization by Parts, Maximal Symmetric Operators, and Quantum Circuits

In the context of a generalized quantum theorywhich admits maximal symmetric operators as observables,we discuss a quantization scheme which cansystematically deal with what may be called quantumcircuits. The scheme, known as the method of quantizationby parts, has recently been applied to obtain a newderivation of the Josephson equation for thesupercurrent through a Josephson junction in asuperconducting circuit. This paper presents an application ofthis scheme to several circuit configurations, namely,from one branch to many-branch circuits. We also proposean experimental test on whether the condensate is always in a pure state, using a three-branchY-shape circuit.     

Classical analogs for Rabi-oscillations,Ramsey-fringes,and spin-echo in Josephson junctions

We investigate the results of recently published experiments on the quantum behavior of Josephson circuits in terms of the classical modeling based on the resistively and capacitively-shunted (RCSJ) junction model. Our analysis shows evidence for a close analogy between the nonlinear behavior of a pulsed microwave-driven Josephson junction at low temperature and low dissipation and the experimental observations reported for the Josephson circuits. Specifically, we demonstrate that Rabi-oscillations, Ramsey-fringes, and spin-echo observations are not phenomena with a unique quantum interpretation. In fact, they are natural consequences of transients to phase-locking in classical nonlinear dynamics and can be observed in a purely classical model of a Josephson junction when the experimental recipe for the application of microwaves is followed and the experimental detection scheme followed. We therefore conclude that classical nonlinear dynamics can contribute to the understanding of relevant experimental observations of Josephson response to various microwave perturbations at very low temperature and low dissipation.     

The dynamics of transients in an overdamped Josephson junction biased by trains of short current pulses with controllable parameters

The paper discusses the development of the method for studying the dynamics of an overdamped Josephson junction biased by a periodic current with controlled parameters, suggested earlier by the authors. The results obtained allow several known experimental observations to be explained. Analytic expressions for the rate of transient process damping and energy expenditures necessary for switching a Josephson junction from one quantum state to another are derived. Problems of interactions between the bias current and supercurrent and the influence of cos?-type terms on the rates of transient process damping and energy conversion are discussed. The results for junction biasing by short (uni-or bipolar) δ function-shaped pulses are obtained in the form of exact analytic expressions. Diagrams illustrating the dependence of the Shapiro step width on the shape of biasing pulses are given.