Electron and Nuclear Spin Interactions in Low-Dimensional Semiconductors

低维半导体中的电子和核自旋相互作用

• 批准号: 1607779
• 负责人: Vanessa Sih
• 金额: $ 52.81万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-06-15 至 2019-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1607779&HistoricalAwards=false
• 关键词: Electron; Nuclear; Spin; Interactions; Low

Non-TechnicalElectrons are fundamental particles that have spin, mass, and charge. The understanding of electronic energy levels has been crucial to understanding chemistry and the development of solid-state materials, such as semiconductors, which have enabled technologies such as computer chips, light-emitting diodes, and solar cells. The logic elements in today's computer chips rely on controlling electron charge and encode information as the presence or absence of charge currents and voltages, but encoding information using electron spin polarization has applications for quantum information processing and potential advantages for improving the speed, efficiency, and energy consumption of logic devices. Electron spins, however, also interact with nuclear spins, and this can be an undesirable source of noise or, if we can understand it better, a pathway for controlling electron spin polarization. The PI will use optical measurements with pulsed lasers to characterize how these spin interactions depend on material strain and other parameters. This research will improve the scientific understanding of these interactions and help us figure out how to control them. The results of this research have the potential to advance multiple scientific and technological areas, including semiconductor physics, device engineering, materials science, magnetism and quantum information. The research will provide valuable training to student researchers in a wide range of techniques, including semiconductor device design and fabrication, optical and electrical measurements, data acquisition and analysis and communicating results through scientific presentations and publications. The proposed outreach and education activities will seek to increase public engagement with recent developments in science and technology and to encourage the participation of underrepresented groups in scientific careers.TechnicalThe proposed research will investigate electron and nuclear spin interactions in low-dimensional semiconductor heterostructures. Controlling the interactions between electron and nuclear spins is of great importance for applications such as classical and quantum information processing, but the understanding of the coupled electron-nuclear spin system is incomplete. Recent experiments on strained quantum dots have revealed unexpected phenomena, including nuclear spin locking, nuclear magnetization at zero magnetic field, and the anomalous Hanle effect. These phenomena have been variously attributed to the effects of quantum confinement, mesoscopic size, and strain, but it is difficult to separate these effects in quantum dots and establish the underlying physical mechanisms. The proposed measurements on strained and unstrained quantum wells will elucidate the role of quantum confinement, carrier localization, reduced symmetry and dimensionality, and spin-orbit effects on electron-nuclear spin interactions. The nuclear polarization will be monitored using ultrafast pump-probe and spin noise optical techniques capable of sensitively measuring small changes to the nuclear spin polarization. The proposed research will advance scientific understanding of the physical origins of recently-observed phenomena in strained quantum dots and address open questions about the coupled electron-nuclear spin system and its interaction with light.

非技术电子是具有自旋、质量和电荷的基本粒子。 对电子能级的理解对于理解化学和半导体等固态材料的发展至关重要，半导体使计算机芯片、发光二极管和太阳能电池等技术成为可能。 当今计算机芯片中的逻辑元件依赖于控制电子电荷并将信息编码为充电电流和电压的存在或不存在，但使用电子自旋极化编码信息可用于量子信息处理，并具有提高逻辑器件的速度、效率和能耗的潜在优势。 然而，电子自旋也会与核自旋相互作用，这可能是一个不受欢迎的噪声源，或者，如果我们能更好地理解它，这可能是控制电子自旋极化的途径。 PI 将使用脉冲激光进行光学测量来表征这些自旋相互作用如何依赖于材料应变和其他参数。 这项研究将提高对这些相互作用的科学理解，并帮助我们弄清楚如何控制它们。 这项研究的成果有可能推动多个科学技术领域的发展，包括半导体物理、器件工程、材料科学、磁学和量子信息。 该研究将为学生研究人员提供广泛技术方面的宝贵培训，包括半导体器件设计和制造、光学和电气测量、数据采集和分析以及通过科学演示和出版物传达结果。 拟议的外展和教育活动将寻求增加公众对科学技术最新发展的参与，并鼓励代表性不足的群体参与科学事业。技术拟议的研究将调查低维半导体异质结构中的电子和核自旋相互作用。 控制电子和核自旋之间的相互作用对于经典和量子信息处理等应用非常重要，但对耦合电子-核自旋系统的理解并不完整。 最近关于应变量子点的实验揭示了意想不到的现象，包括核自旋锁定、零磁场下的核磁化和反常汉勒效应。 这些现象被不同程度地归因于量子限制、介观尺寸和应变的影响，但很难在量子点中分离这些影响并建立潜在的物理机制。 所提出的对应变和非应变量子阱的测量将阐明量子限制、载流子局域化、对称性和维数降低以及自旋轨道效应对电子-核自旋相互作用的作用。 将使用超快泵浦探针和自旋噪声光学技术来监测核极化，这些技术能够灵敏地测量核自旋极化的微小变化。 拟议的研究将促进对最近观察到的应变量子点现象的物理起源的科学理解，并解决有关电子-核自旋耦合系统及其与光相互作用的悬而未决的问题。