Study of Quantum Hall Liquids using Single Electron Transistors

* 非技术摘要 ** 在强磁场中，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新物质状态。在这样的物质中，新的粒子出现了非常不寻常的性质。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。在超导体中，电流由电荷为2 e的电子对携带。相比之下，在分数量子霍尔液体中，电流是由具有e/3、e/5等分数电荷的不寻常粒子携带的。由于电子是不可分割的，这种分数电荷粒子的出现是许多电子量子现象中最令人着迷的表现之一。这个项目将使用称为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单个电子打开和关闭，因此是现有的最灵敏的电荷传感器。使用这种类型的高灵敏度晶体管，量子霍尔液体的磁性也将被探索。在教育方面，该项目将为参与的研究生和本科生提供半导体物理和纳米科学方面的优质培训。此外，我们亦会与本地科学馆合办外展活动，以提高幼儿园至12年级学生对科学及工程的兴趣。 * 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携带分数电荷，并服从不同于费米子或玻色子的不寻常的分数统计。准粒子的分形和统计将使用反点几何中的单电子晶体管进行研究，这将使研究人员能够进行噪声和Aharonov-Bohm类型的干涉实验。首先在反点周围的边缘状态加载可控量的电荷，然后通过在干涉实验中监测相变来解决载流子的统计数据。使用单电子晶体管来研究量子霍尔液体中的体输运性质，将使研究深入到绝缘制度，传统的输运测量无法进行。在教育方面，该项目将为参与的研究生和本科生提供半导体物理和纳米科学方面的出色培训。此外，我们亦会与本地科学馆合办外展活动，以提高幼儿园至12年级学生对科学及工程的兴趣。

******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. In superconductors, current is carried by pairs of electrons with a charge of 2e. 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 thus the most sensitive charge sensor in existence. Using this type of a highly sensitive transistor, magnetic properties of quantum Hall liquids will also be explored. On the educational side, the project will provide excellent training for participating graduate and undergraduate students in semiconductor physics and nanoscience. In addition, an outreach activity will be mounted in collaboration with a local science museum to promote the interest of K-12 students in science and engineering. ******TECHNICAL ABSTRACT******This project will address some 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 in an antidot geometry, which will allow the researchers to perform both noise and Aharonov-Bohm type interference experiments. The statistics of the carriers will be addressed by first loading the edge states around the antidot with a controllable amount of charge and then by monitoring the phase change in an interference experiment. The use of single electron transistors to study bulk transport properties in quantum Hall liquids will enable investigations deep in the insulating regime where conventional transport measurements cannot be performed. On the educational side, the project will provide excellent training for participating graduate and undergraduate students in semiconductor physics and nanoscience. In addition, an outreach activity will be mounted in collaboration with a local science museum to promote the interest of K-12 students in science and engineering.