Nuclear Hyperpolarization in Semiconductors

技术摘要这项工作旨在理解和控制导致核自旋角动量的物理过程。在半导体材料中，通过电子-核交叉弛豫将产生大规模非热核自旋极化，其中电子已经通过光泵浦或自旋注入方法制备本征态。这项工作将开始与电子核交叉弛豫的一系列材料，工程测试机制的核超极化的系统研究。在这些研究的过程中，新材料中的核超极化被预期，如果过去是任何迹象，新的现象也将显现。这项工作将使用新开发的核超极化的理解来设计新的实验，并建立测试和利用电子-核耦合的设备。这些装置包括自旋注入传递大量的核极化到无机固体，制备超极化的纳米级区域，以及这些和其他装置的耦合，以便制备高自旋极化溶剂的储库。非技术摘要周期表上的许多原子的原子核具有称为自旋的性质，该性质使磁共振成像或MRI等技术成为可能。还有许多其他技术可以利用原子的这一基本性质，但这些技术被排除在商业开发之外，因为检测核自旋的方法的灵敏度太低。组成原子和分子的电子也有自旋，这种电子自旋可以用光和磁性材料来操纵。该项目将支持两名学生，分别来自加州大学伯克利分校和纽约城市学院，操纵电子自旋，以便以极大增强的灵敏度检测附近的核自旋。 进行这些研究有两个原因：第一是电子和核自旋之间的相互作用具有内在的科学兴趣;第二是在电子自旋附近控制核自旋可以大大提高MRI等方法的灵敏度，但也可能导致新量子计算机的设计。

Technical AbstractThe work seeks to understand and control the physical processes leading to nuclear spin angular momentum. Massively athermal nuclear spin polarizations will be generated via electron-nuclear cross-relaxation in semiconducting materials, where the electrons have been eigenstate-prepared by optical pumping or spin-injection methods. The work will begin with a systematic study of electron-nuclear cross relaxation in a host of materials that are engineered to test mechanisms for nuclear hyperpolarization. In the course of these studies nuclear hyperpolarization in new materials is anticipated, and if the past is any indication, new phenomenology will also be manifest. This work will use the newly developed understanding of nuclear hyperpolarization to design new experiments and build devices that test and exploit electron-nuclear couplings. These devices include spin-injection delivery of massive nuclear polarization to inorganic solids, the preparation of nanoscale regions of hyperpolarization, and the coupling of these and other devices so as to prepare reservoirs of highly spin-polarized solvents.Non-Technical AbstractThe nuclei of many atoms on the Periodic Table possess a property known as spin, a property that has enabled technologies such as magnetic resonance imaging, or MRI. There are many other technologies that could exploit this fundamental property of atoms, yet these technologies are precluded from commercial development because the sensitivity of the methods that detect nuclear spin is too low. The electrons that comprise atoms and molecules also have spin, and this electron spin can be manipulated with light and magnetic materials. This project will support two students, one each at UC Berkeley and City College of New York, to manipulate electron spins so that nearby nuclear spins can be detected with greatly enhanced sensitivity. There are two reasons for conducting these studies: the first is that the interaction between electrons and nuclear spins is of inherent scientific interest; the second is that control of nuclear spins in the vicinity of electrons spins could both greatly enhance the sensitivity of methods such as MRI, but could also lead to the design of new quantum computers.