Quantum Transport in Ballistic Nanostructures

技术概述：该奖项支持纳米尺度电子传输领域的理论研究和教育。与量子相干传输相关的理论问题将被用来解决几个悬而未决的理论问题和实验结果。将涉及两个研究领域。第一个推力涉及限制量子干涉的物理学：依赖时间的势和场的散射。在无序金属线中，断相理论已经建立，但在量子点和铁磁体方面还需要做大量的工作。PI的目的是发展一种微观的双量子点断相理论，在该理论中可以获得控制断相率强度的所有参数。在铁磁导体中，实验表明，强(元素)铁磁体的断相率比普通金属大得多，尽管这种增强的机制尚不清楚。已经探索了一些候选机制，例如波动的磁场壁、磁子和杂质，但这幅图还不完整，将进行进一步的研究。第二个推力涉及量子干涉校正本身。这项研究促进了弹道导体理论的发展。此外，这项研究还解决了量子干涉校正如何以及何时取决于微观运动是弹道运动还是量子无序运动的问题。这项研究的目标是扩展这一理论，并着眼于涉及干涉以及电子-电子相互作用的量子修正。非技术概述：该奖项支持纳米尺度上关于尺寸效应和材料性质变化的理论研究和教育，目的是增强我们预测和表征携带电流的纳米结构和纳米器件的能力。随着纳米技术发展到更小的器件组件，电荷在电路中的运动变得不像传统电子学那样，这种行为必须用量子力学来描述。电流的波动描述包括散射和干扰以及其他电子的影响。PI将研究电子在尺寸小于百万分之一英寸的设备中流动的量子理论。纳米器件的几何形状使得这一点变得复杂，而波在附近器件组件中的相互作用还没有得到很好的理解，这也是本研究的一个主要方面。如果我们要真正实现电子学的微型化，达到几百个左右的原子大小，就需要在这方面取得进展。让研究生和本科生参与到这些前沿技术背后的理论物理中，这对本科生来说是有启发性的，对研究生来说也是一个很好的职业起点。该奖项通过为未来技术的智力基础和培训具有全球竞争力的劳动力做出贡献，为保持美国的竞争力做出了贡献。

TECHNICAL SUMMARY: This award supports theoretical research and education in the area of electronic transport on nanoscale length scales. Theoretical issues connected with quantum coherent transport will be addressed to resolve several outstanding theoretical questions and experimental results that remain unexplained. Two research areas will be engaged. The first thrust addresses the physics that limits quantum interference: scattering from time-dependent potentials and fields. In disordered metal wires, the theory of phase breaking is established, but much work is needed in quantum dots and ferromagnets. The PI aims to develop a microscopic theory of phase breaking in a 'double quantum dot', in which all parameters that govern the strength of the phase-breaking rate can be accessed. In ferromagnetic conductors, experiment suggests that the phase-breaking rates in 'strong' (elemental) ferromagnets are much larger than in normal metals, although the mechanism for this enhancement is unclear. Some candidate mechanisms, for example fluctuating domain walls, magnons, and impurities, have been explored, but the picture is incomplete and will be investigated further. The second thrust deals with the quantum interference corrections themselves. The research advances the theory in ballistic conductors. In addition, the research addresses the question of how and when quantum interference corrections depend on whether the microscopic motion is ballistic or quantum-disordered. A goal of this research is to extend the theory, and to look at quantum corrections that involve interference as well as electron-electron interactions.NON-TECHNICAL SUMMARY:This award supports theoretical research and education on size effects and alterations of materials properties at the nanoscale, with an aim to enhancing our ability to make predictions and characterizations for current carrying nanostructures and nanodevices. As nanotechnology progresses to even smaller device components, the movement of electric charge through the circuits becomes less like traditional electronics and the behavior must be described in terms of quantum mechanics. The wave description of electric current includes scattering and interference and the influence of other electrons. The PI will work on the quantum theory of electrons that flow in devices that are smaller than a millionth of an inch in size. The geometries of nanodevices make this complex and the interaction of waves in nearby device components is not well understood and so is a main aspect of this research. Advances in this are required if we are ever to actually reach a miniaturization of electronics to the size of a few hundred or so atoms. Engaging students, graduate and undergraduate, in the theoretical physics behind such leading edge technology is both enlightening for undergraduates and an excellent career starting point for dissertation student. This award contributes to the effort to keep America competitive both through contributing to the intellectual foundations of future technologies and to the training of globally competitive workforce.