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

摘要：在高磁场下，被限制在两个方向上运动的电子形成了被称为分数量子霍尔液体的物质的新状态。在这种物质中，新粒子的出现具有非常不寻常的性质。例如，在大多数导体中，电流通常由带有众所周知的e电荷的电子携带。相反，在分数量子霍尔液体中，电流由带有e/3、e/5等分数电荷的不寻常粒子携带。由于已知电子是不可分割的，所以这种部分带电粒子的出现一直是许多电子量子现象中最迷人的表现之一。这个项目将使用一种叫做单电子晶体管的设备来研究这些迷人的新粒子。单电子晶体管可以通过一个电子打开和关闭，是目前最灵敏的电荷传感器。这种强大的晶体管也将用于研究这些不寻常液体堆叠层的磁性。除了传统的半导体结构，这项工作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。以半导体为主题的物理演示和公开讲座等活动将使参加活动的当地高中生受益。技术摘要：本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被预测为携带分数电荷，并遵循不同于费米子或玻色子的不寻常的分数统计。在Aharonov-Bohm型干涉结构中，利用单电子晶体管（SETs）研究准粒子的分形和统计。set还将用于研究量子霍尔液体的体输运性质。特别是纵向电导率测量将在深层绝缘状态下进行，传统的传输测量是不可行的。将研究量子霍尔液体堆叠层中的持续涡流，以测试一个有趣的预测，即这种堆叠层可以在零温度下完全抗磁性。除了GaAs/AlGaAs异质结构外，基于高带隙半导体的新兴二维电子系统的量子输运特性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。以半导体为主题的物理演示和公开讲座等活动将使参加活动的当地高中生受益。

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.