Quantum Fluctuations of the Order Parameter in Superconductors

超导体中有序参数的量子涨落

• 批准号: 0120702
• 负责人: Anatoly Larkin
• 金额: $ 27万
• 依托单位: University of Minnesota-Twin Cities
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-11-01 至 2005-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0120702&HistoricalAwards=false
• 关键词: Quantum; Fluctuations; Order; Parameter; Superconductors

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.***

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。 计划开展三个项目：（1）研究人员将计算对超导薄膜中上临界场的现有平均场理论的修正。 他们将考虑杂质分布中的介观效应，导致BCS上临界场以上超导液滴的出现。 超导液滴的约瑟夫森网络可以在低温下变得宏观超导。真正的跃迁点是由序参量的量子涨落和邻近效应的相互作用决定的。 各种物理量的行为附近的过渡将被认为是与现有的标度理论的联系。(2)研究人员将建立一个理论的零温度超导转变在有限长的电线和约瑟夫森结链。 这项工作的动机是实验表明，在低温下的热激活电阻率的偏差。(3)研究人员将计算铁磁-d波超导体结的I-V特性，包括自旋-轨道耦合的影响。图表展开和凯尔迪什技术是各种分析技术，将被使用。该奖项支持低温超导体量子力学波动的理论研究和教育。 研究人员将使用先进的理论方法来研究量子涨落在超导薄膜、超导导线和超导体结中的作用。这项研究是基础性的，对我们理解其他系统中的量子相变有潜在的影响。