Numerical study of dephasing in disordered electron systems

在这个项目中，我们研究了无序电子系统中的量子输运的数值退相和相关主题，其中复杂的量子干涉起着重要的作用。这种干涉在低维系统如二维电子系统（2DES）中尤其重要。由于耦合到外部自由度（例如热浴）而导致的干扰的崩溃是失相的起源。将额外的导线连接到储液器是在数值计算中考虑失相的一种方法。因此，在本项目中，我们研究了以下内容：1）研究电子输运在3终端几何：考虑到退相，研究系统的两个以上的终端是必要的。我们已经开发了一个程序来研究这个问题，并计算了输运系数。作为一个副产品，我们分析了自旋极化电流的产生存在的自旋轨道相互作用。（论文2、4）2 关于我们 研究自旋在量子输运现象中的作用：研究了自旋自由度在量子输运中的作用。特别感兴趣的是在低维系统中具有强自旋轨道散射的系统。我们模拟了电导涨落（论文10）、二维DES中的安德森跃迁（论文8和15）和二维以下的安德森跃迁（论文1）。通过假设随时间变化的势，在2DES中研究了存在自旋轨道散射的失相（论文14）. 3）随机相位模型的研究：为了研究相位在量子输运中的重要性，我们研究了随机相位模型（论文6和11）。4）量子网络模型研究：网络模型是研究量子输运现象的简化模型（论文5）。由于模型简单，我们可以在一个样品上附加许多线索。5）量子霍尔效应中边缘态的研究：量子霍尔边缘态具有非常长的退相时间。我们已经详细研究了这些状态中存在的障碍（文件3和7）。少

In this project, we have studied numerically dephasing and related topics in quantum transport in disordered electron systems where complex quantum interference plays an important role. The interference is especially important in low dimensional systems such as the 2 dimensional electron system (2DES). The breakdown of the interference due to the coupling to external degrees of freedom such as a heat bath is the origin of dephasing. Attaching extra lead(s) coupled to reservoir(s) is a way to take into account the dephasing in numerical calculations. In this project, therefore, we have studied the following :1) Study of electron transport in the 3 terminal geometry : to take into account the dephasing, study of systems with more than two terminals is needed. We have developed a program to study this issue, and have calculated the transport coefficients. As a byproduct, we have analyzed the generation of spin polarized current in the presence of spin-orbit interaction. (Papers 2 and 4.)2 … More ) Study of the role of spin in quantum transport phenomena : the role of the spin degree of freedom in quantum transport has been studied. Of particular interest is the system with strong spin-orbit scattering in low dimensional systems. We have simulated conductance fluctuations (paper 10), the Anderson transition in 2DES (papers 8 and 15) and the Anderson transition below 2 dimensions (paper 1). Dephasing in the presence of spin-orbit scattering has been studied in the 2DES by assuming a time-dependent potential (paper 14).3) Study of random phase model : to investigate the importance of phase in quantum transport, we have studied the random phase model (papers 6 and 11).4) Study of quantum network model : the network model that is a simplified model to study the quantum transport phenomena has been studied (paper 5). Since the model is simple, we are able to attach many leads to a sample.5) Study of edge states in the quantum Hall effect : the quantum Hall edge states are know to have extraordinary long dephasing time. We have studied these states in the presence of disorder in detail (papers 3 and 7). Less