Study of Quantum Hall Liquids Using Single Electron Transistors and Emerging Two-Dimensional Electron Systems

非技术摘要：在高磁场下，被限制在两个方向上移动的电子形成新的物质状态，称为分数量子霍尔液体。在这种情况下，新粒子的出现具有非常不寻常的特性。例如，在大多数导体中，电流通常由具有众所周知的电荷 e 的电子携带。相比之下，在分数量子霍尔液体中，电流由分数电荷为 e/3、e/5 等的不寻常粒子携带。由于已知电子是不可分割的，因此这种分数带电粒子的出现一直是许多电子量子现象最令人着迷的表现之一。该项目将使用称为单电子晶体管的设备来研究这些令人着迷的新粒子。单电子晶体管可以通过单个电子来打开和关闭，是现有的最灵敏的电荷传感器。这种强大的晶体管还将用于研究这些不寻常液体的堆叠层的磁性。除了传统的半导体结构之外，这项工作还将扩展到基于更高带隙半导体的新兴二维电子系统。在教育方面，该项目将为研究生和本科生提供优秀的培训。物理演示和公开讲座等外展活动通常侧重于半导体，将使参与的当地高中生受益。技术摘要：该项目将解决二维电子系统中一些长期存在的基本问题。分数量子霍尔液体的激发预计会携带分数电荷，并服从与费米子或玻色子不同的不寻常的分数统计。将使用 Aharonov-Bohm 型干涉结构中的单电子晶体管 (SET) 研究准粒子的分级和统计。 SET 还将用于研究量子霍尔液体中的整体传输特性。特别是纵向电导率测量将在传统传输测量无法进行的深层绝缘区域中进行。将在量子霍尔液体堆叠层中研究持续涡流，以测试这样的堆叠层在零温度下可以完全抗磁性的有趣预测。除了 GaAs/AlGaAs 异质结构之外，基于较高带隙半导体的新兴二维电子系统的量子输运特性还将在门控霍尔棒和量子点接触结构中进行研究。在教育方面，该项目将为研究生和本科生提供优秀的培训。 物理演示和公开讲座等外展活动通常侧重于半导体，将使参与的当地高中生受益。

Non-technical Abstract:At high magnetic fields, electrons that are confined to move in two directions form new states of matter known as fractional quantum Hall liquids. In such matter, new particles emerge with very unusual properties. For example, in most conductors electrical current is normally carried by electrons with a well-known charge of e. By contrast, in fractional quantum Hall liquids, current is carried by unusual particles with fractional charge of e/3, e/5, and so on. Since electrons are known to be indivisible, the emergence of such fractionally charged particles has been one most fascinating manifestations of many electron quantum phenomena. This project will study these fascinating new particles using devices called single electron transistors. The single electron transistor can be turned on and off by a single electron, and is the most sensitive charge sensor in existence. This powerful transistor will also be used to study magnetic properties of stacked layers of these unusual liquids. In addition to conventional semiconductor structures, the work will expanded to emerging two-dimensional electron systems based on higher bandgap semiconductors. On the educational side, the project will provide excellent training for graduate and undergraduate students. The outreach activities, such as physics demonstrations and public lectures, which typically focus on semiconductors, will benefit participating local high school students. Technical Abstract:This project will address some of the long-standing fundamental problems in two-dimensional electron systems. Excitations of fractional quantum Hall liquids are predicted to carry fractional charge and obey unusual fractional statistics different from those of fermions or bosons. Fractionalization and statistics of quasiparticles will be studied using single electron transistors (SETs) in an Aharonov-Bohm type interference structure. SETs will also be used to study bulk transport properties in quantum Hall liquids. In particular longitudinal conductivity measurements will be performed in the deep insulating regime where conventional transport measurements are not doable. Persistent eddy currents will be investigated in stacked layers of quantum Hall liquids to test an interesting prediction that such stacked layers can be perfectly diamagnetic at zero temperature. In addition to GaAs/AlGaAs heterostructures, quantum transport properties of emerging two-dimensional electron systems based on higher bandgap semiconductors will be investigated in both gated Hall bar and quantum point contact structures. On the educational side, the project will provide excellent training for graduate and undergraduate students. The outreach activities, such as physics demonstrations and public lectures, which typically focus on semiconductors, will benefit participating local high school students.