Nuclear Hyperpolarization in Semiconductors

技术摘要：本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，通过光抽运或自旋注入方法制备本征态的电子将通过电子-核交叉弛豫产生大量的非热核自旋极化。这项工作将从系统地研究大量材料中的电子-核交叉弛豫开始，这些材料被设计用来测试核超极化的机制。在这些研究过程中，预计新材料中的核超极化，如果过去有任何指示，新的现象学也将显现。这项工作将利用新发展的对核超极化的理解来设计新的实验和建造测试和利用电子-核耦合的设备。这些装置包括自旋注入将大量核极化输送到无机固体，制备纳米级超极化区域，以及将这些装置与其他装置耦合以制备高自旋极化溶剂储存器。元素周期表上许多原子的原子核具有一种被称为自旋的特性，这种特性使磁共振成像（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特性，但由于检测核自旋的方法的灵敏度太低，这些技术被排除在商业开发之外。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，从而以大大提高的灵敏度检测到附近的核自旋。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；其次，控制电子自旋附近的核自旋不仅可以大大提高MRI等方法的灵敏度，而且还可以设计出新的量子计算机。

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.