Coherent spin control and geometrical phases in mesoscopic conductors

我们计划采用量子输运特性，如弱（反）本地化，电导波动和Aharonov-Bohm效应，作为一个探针的自旋动力学和相关的几何相位在封闭导体复杂的能带拓扑结构。一方面，我们将考虑具有Rashba和Dresselhaus自旋轨道耦合的量子线和环，并研究禁闭和自旋弛豫之间的相互作用，重点关注立方Dresselhaus项的作用。基于最近对自旋轨道比α/β的全电探测工作，我们将研究α/β对自旋相干性的影响，特别是对通过环输运的Aharonov-Casher相的影响。另一方面，我们提出了一个半经典路径积分方法的量子电导的扩散和弹道孔系统的基础上，四带模型和调用Berry曲率效应，与长期的目标是设计半经典的拓扑量子态在介观几何。此外，这两个相互关联的研究路线旨在为Nitta和韦斯小组进行的相应实验做出预测。我们将使用一个强大的数值传输代码来检查的分析预测，并采用现实的模型与实验进行比较。

We plan to employ quantum transport characteristics, such as weak (anti-)localization, conductance fluctuations and the Aharonov-Bohm effect, as a probe of spin dynamics and associated geometrical phases in confined conductors with complex band topologies. On the one hand, we will consider quantum wires and rings with Rashba- and Dresselhaus spin-orbit coupling and investigate the interplay between confinement and spin relaxation, focusing in the role of the cubic Dresselhaus term. Based on recent work on all-electrical detection of the spin-orbit ratio α/β, we will study α/β-effects on spin coherence, in particular on Aharonov-Casher phases in transport through rings. On the other hand, we propose to develop a semiclassical path-integral approach to the quantum conductance in diffusive and ballistic hole systems, based on four-band models and invoking Berry curvature effects, with the longterm aim to devise semiclassics for topological quantum states in mesoscopic geometries. Both interrelated research lines furthermore aim at making predictions for corresponding experiments to be pursued in the Nitta and Weiss groups. We will use a powerful numerical transport code to check the analytical predictions and to employ realistic models to compare with experiment.