Quantum Fluctuations of the Order Parameter in Superconductors

该奖项支持理论研究和教育，以研究低维超导体中的量子涨落。计划进行三个项目：(1)研究人员将计算现有超导体薄膜上临界场平均场理论的修正。他们将考虑杂质分布中的介观效应，这些介观效应会导致超导液滴在BCS上部临界场上方出现。超导液滴的约瑟夫森网络在低温下可能成为宏观超导。真正的过渡点是由序参量的量子涨落和邻近效应的相互作用决定的。将考虑各种物理量在过渡附近的行为，并与现有的标度理论进行联系。(2)研究人员将构建有限长度Josephson结导线和链中的零温度超导跃迁理论。这项工作的动机是在低温下显示热活化电阻率偏差的实验。(3)研究人员将计算铁磁体- d波超导结的I-V特性，包括自旋轨道耦合的影响。图解展开和Keldysh技术是将使用的各种分析技术之一。该奖项支持超导体低温下量子力学涨落的理论研究和教育。研究人员将使用先进的理论方法来研究超导体薄膜、超导导线和超导体结中量子涨落的作用。这项研究是基础性的，对我们理解其他系统中的量子相变具有潜在的影响

This award supports theoretical research and education to study quantum fluctuations in low-dimensional superconductors. Three projects are planned: (1) The investigators will calculate corrections to the existing mean-field theory of the upper critical field in thin superconducting films. They will consider mesoscopic effects in the distribution of impurities that lead to the appearance of superconducting droplets above the BCS upper critical field. The Josephson network of the superconducting droplets may become macroscopically superconducting at low temperatures. The genuine transition point is determined by the interplay of the quantum fluctuations of the order parameter and the proximity effect. The behavior of various physical quantities near the transition will be considered and contact with the existing scaling theory will be made. (2) The investigators will construct a theory of the zero-temperature superconducting transition in finite-length wires and chains of Josephson junctions. This work is motivated by experiments that show deviations from a thermally activated resistivity at low temperatures. (3) The investigators will calculate I-V characteristics for a ferromagnet - d-wave superconductor junction including the effects of spin-orbit coupling. Diagrammatic expansions and the Keldysh technique are among the variety of analytical techniques that will be used. %%% This award supports theoretical research and education on quantum mechanical fluctuations in superconductors at low temperatures. The investigators will use advanced theoretical methods to study the role of quantum fluctuations in thin superconducting films, superconducting wires, and junctions involving superconductors. This research is fundamental and has potential impact on our understanding of quantum phase transitions in other systems.***