Imaging Electron States in Nanostructures

****技术摘要****随着电子结构尺寸的不断减小，电子运动的经典观点转变为基于电子态和波函数相互作用的全量子图景。为了理解这幅量子图景，我们需要可视化电子在哪里，并理解它们是如何运动的。利用库仑封锁光谱，利用液体- he冷却扫描探针显微镜（SPM）来提取半导体纳米结构内部单个电子态的能量和波导。样品是InAs/InP纳米线中的一个长而细的InAs量子点，其中包含一排形成一维电子气体的电子。波函数可以通过SPM尖端局部凹痕波函数成像，SPM尖端充当可移动门，并记录随着尖端沿着点移动而产生的量子态能量变化。该小组计划研究随着电子数量的增加，从维格纳晶体到卢廷格液体的预测转变。研究和教育将通过研究生的培训和本科生的暑期研究经验相结合。****非技术摘要****随着电子器件尺寸的减小，量子力学变得越来越重要。我们对电子运动的经典观点转变为基于相互作用的电子态和波函数的量子图像。目前正在开发一种利用冷却扫描探针显微镜（SPM）测量单个电子态能量并绘制其波函数图的技术。一排电子被固定在InAs/InP纳米线形成的长量子点内——纳米线非常窄，电子必须一个接一个地排列。单个电子状态的能量是用库仑封锁光谱测量的——只有当增加或去除电子所需的能量降至零时，电流才能流过点。通过用带电荷的SPM尖端凹痕波函数来映射波函数，并测量当尖端沿着点移动时量子态能量的变化。通过这种方式，SPM可以将量子图像可视化，从而从纳米结构中开发新型量子器件。研究和教育将通过研究生的培训和本科生的暑期研究经验相结合。

****Technical Abstract****As the size of electronic structures continues to decrease, the classical view of electron motion transforms into a fully quantum picture based on interacting electron states and wavefunctions. To understand this quantum picture, we need to visualize where electrons are and understand how they move. A liquid-He cooled scanning probe microscope (SPM) is used to extract both the energy and the wavefuction of individual electron states inside a semiconductor nanostructure, using Coulomb blockade spectroscopy. The sample is a long, thin InAs quantum dot in an InAs/InP nanowire, which contains a row of electrons that form a one-dimensional electron gas. The wavefunction can be imaged by locally denting the wavefunction with the SPM tip, which acts as a moveable gate, and recording the resulting change in energy of the quantum state as the tip is moved along the dot. The group plans to investigate the predicted transition from a Wigner crystal to a Luttinger liquid as the number of electrons is increased. Research and education will be integrated through the training of graduate students, and through summer research experiences for undergraduate students.****Non-Technical Abstract****As the size of electronic devices decreases, quantum mechanics becomes increasingly important. Our classical view of electron motion transforms into a quantum picture based on interacting electron states and wavefunctions. A technique is being developed to measure the energy of individual electron states and map their wavefunctions using a cooled scanning probe microscope (SPM). A row of electrons is held inside a long quantum dot formed in an InAs/InP nanowire - the nanowire is so narrow that the electrons must line up, one after the other. The energy of a single electron state is measured using Coulomb blockade spectroscopy - current can flow through the dot only when the energy required to add or remove an electron drops to zero. The wavefunction is mapped by denting the wavefunction with the charged SPM tip, and measuring the change in energy of the quantum state as the tip is moved along the dot. In this way, the SPM can visualize the quantum picture in order to develop new types of quantum devices from nanostructures. Research and education will be integrated through the training of graduate students, and through summer research experiences for undergraduate students.