Vortex Motion and Dynamical States in Josephson Arrays

这个实验研究项目专注于约瑟夫森结阵列的物理、动态激发和潜在的应用，约瑟夫森结是一种非线性相互作用的器件。主要研究三个方面：(1)新颖的、通用的动力学状态，包括每个分支上都有结点的完全受挫阵列，其中动力学可以归结为三个动力学变量。(2)电感耦合阵列，构成高温超导体耦合层和非线性振子耦合系统的模型系统。(3)二维阵列中的磁通流动将为研究高温超导体薄膜中类似的涡旋动力学提供一个模型系统。对该系统中涡旋运动的研究将有助于阐明离散系统中类摆涡动模式的某些方面。还将研究与局部和全局锁相机制相对应的其他动力学状态。这项研究的特点是实验、数值模拟和数学分析相结合，并将利用现有的商业铸造服务来制造约瑟夫森结阵列。这个实验研究项目是可以存在于二维非线性相互作用系统(约瑟夫森结)中的“运动”或激发类型。励磁的一个例子是捕获在一个闭合回路中的磁通量量子(涡旋)，超电流通过这个闭合回路流动。这样的旋涡可以在晶格周围移动，也可以与同时存在的其他旋涡相互作用。描述这种系统的数学方程是非线性的，可以有称为孤子的奇异解，这在科学的其他领域中也有相当大的兴趣。事实上，将在主要部分进行的项目将试图对其他感兴趣的系统的行为进行建模，包括高温超导体中磁通运动的各个方面。研究人员将把实验测量与数值模拟以及更传统的分析数学相结合，以了解观察到的行为，这可能会对其他系统产生影响，而不是专门针对手头的系统。在其一个方面，约瑟夫森结阵列可能在检测和产生微波辐射方面有应用，这也将是本项目感兴趣的。这项研究的结果可能包括不同寻常的新效果或装置，可能会在技术上找到新的应用。这项研究项目本质上是跨学科的，涉及将接受良好培训以进入工业、政府或教育职位的研究生。该项目还将促进将妇女和代表性不足的群体纳入国家科学工作队伍。***

w:\awards\awards96\num.doc 9610042 Orlando This experimental research project focuses on the physics, dynamical excitations, and potential applications of arrays of Josephson junctions, devices which nonlinearly interact. Three areas are to be studied: (1) Novel and universal dynamical states, including a fully frustrated array with junctions along every branch, where the dynamics can be reduced to three dynamical variables. (2) Inductively coupled arrays, which form a model system for coupled layers of high-temperature superconductors and for coupled systems of nonlinear oscillators. (3) Flux-flow in 2-d arrays will provide a model system for investigating the similar vortex dynamics that occurs in thin films of high temperature superconductors. The study of vortex motion in this system will clarify aspects of pendula-like whirling modes in discrete systems. Other dynamical states corresponding to local and global phase-locking mechanisms will be also be studied. The research is characterized by integration of experiment, numerical simulation, and mathematical analysis, and will exploit existing commercial foundry service for fabrication of arrays of Josephson junctions. %%% This experimental research project is in the types of "motions" or excitations that can exist in a two-dimensional array of non- linearly interacting systems (Josephson junctions). One example of an excitation is a magnetic flux quantum (vortex) trapped within a closed loop through which a supercurrent flows. Such vortices can move about the lattice, and can also interact with other vortices which simultaneously exist. The mathematical equations describing such systems are non-linear and can have singular solutions called solitons, in which considerable interest exists in other areas of science. In fact, the project to be carried out in major parts will attempt to model the behavior of other systems of interest, including aspects of the motion of magnetic flux in high temperature superconductors. The researchers will combine experimental measurements with numerical simulations and with more conventional analytical mathematics to understand the observed behavior, which may have implications on additional systems than the systems specifically at hand. In one of its aspects the array of Josephson junctions may have applications in detecting and in generating microwave radiation, which will also be of interest in this project. Results from this research may include unusual new effects or devices which may find new application in technology. This research project is interdisciplinary in nature and involves graduate students who will be excellently trained to enter positions in industry, government or education. The project will also foster inclusion of women and under-represented groups into the national scientific work force. ***