Experimental Study of the RKKY Interaction in Multi-Quantum-Dot Systems

* 非技术性摘要 * 自旋，顾名思义，是电子的一个基本性质，描述了它们的角动量（就像它们在自旋一样）和相关的磁性。虽然现代电子主要使用电子的电荷来编码信息，但电子自旋也对我们有用，特别是在硬盘驱动器，信用卡条和任何其他磁性存储介质中。 然而，自旋提供了一个更强大的应用-一个尚未出现在任何技术中的应用，但理论表明，通过利用量子力学定律，它可能会导致计算和通信的革命性改进。该项目旨在通过实验研究自旋取向信息如何以内在量子力学方式在电子之间传递。而不是在自然环境中研究电子，例如，在金属中（很难探测和控制），这个项目将用纳米级的半导体器件（量子点）制造人工电子系统，从而对单个电子进行更大的控制。在量子点中，自旋可以通过旋钮的转动来耦合和解耦，就像在晶体管中一样。 通过构建人工电子系统和研究自旋信息是如何传递的，该项目旨在了解远程耦合如何用于未来技术的局限性，在未来技术中，编程信息被编码在电子自旋中。从事这些项目的学生将学习技能，使他们能够成为学术或工业社区的生产成员。技术摘要 * 本项目将探索非局域自旋-自旋相互作用，类似于研究充分的Ruderman-Kittel-Kasuya-Yosida（RKKY）相互作用，在基于栅极定义的GaAs量子点的人工制造的自旋系统中，金属中的局域自旋之间的相互作用。具体的实验将（1）研究RKKY和Kondo效应之间的竞争，旨在阐明强相关电子材料中这种竞争的可控性较低的对应物，（2）探索由弹道电子或小的受限费米海介导的RKKY相互作用，以及（3）通过弱局域化测量观察自旋耦合对电子海本身的退相效应。 该项目的第二个主要目标是探索使用自旋作为量子信息的保持器。由于RKKY相互作用传递自旋信息的非局域性，它是一个有趣的候选人，以调解的自旋信息的远程传输为基础的量子信息处理。然而，自旋与电子海的耦合可能会导致量子相干性的损失，类似于柯林加弛豫。本项目开发的实验技术将确定使用RKKY相互作用的自旋信息的远程通信是否可能用于未来的技术。参与这项研究的学生将获得未来职业生涯所需的知识和技能，在工业或国家实验室。

*****NON-TECHNICAL ABSTRACT*****Spin, as the name suggests, is a fundamental property of electrons describing their angular momentum (as if they were spinning) and associated magnetic properties. While modern electronics predominantly use the charge of the electron to encode information, electron spin is also working for us, notably in hard drives, credit card strips, and any other magnetic storage medium. However, spin offers a much more powerful application-one that has yet to appear in any technology, but which theory has shown could lead to revolutionary improvements in computation and communication by tapping the laws of quantum mechanics. This project aims to study experimentally how information about spin orientation is conveyed between electrons in an intrinsically quantum mechanical way. Rather than investigating electrons in their natural environment, e.g., in a metal (which is difficult to probe and control), this project will fabricate artificial electronic systems from nanoscale semiconductors devices known as quantum dots, allowing far greater control over individual electrons. In quantum dots, spins can be coupled and uncoupled with the turn of a knob, as in a transistor. By constructing artificial electronic systems and investigating how spin information is communicated, the project aims to learn the limits of how long-range coupling can be used for future technologies in which programmed information is encoded in electron spin. The students working on these projects will learn skills that will enable them to become productive members of the academic or industrial communities.*****TECHNICAL ABSTRACT*****This project will explore non-local spin-spin interactions, analogs of the well-studied Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction between localized spins in metals, in an artificially fabricated spin system based on gate-defined GaAs quantum dots. Particular experiments will (1) investigate the competition between RKKY and Kondo effects, aiming to shed light on less controllable counterparts of this competition in strongly correlated electronic materials, (2) explore RKKY interactions mediated by ballistic electrons or a small confined fermi sea, and (3) to observe the dephasing effects of spin coupling on the electron sea itself through weak localization measurements. A second main goal of the project is to explore the use of spin as a holder of quantum information. Because the RKKY interaction conveys spin information nonlocally it is an interesting candidate to mediate the long-range transfer of spin information for spin-based quantum information processing. However, the coupling of spins to an electron sea presumably leads to losses of quantum coherence analogous to Korringa relaxation. Experimental techniques developed in this project will determine if long-range communication of spin information using RKKY interactions are possible for future technologies. The students involved with this research will obtain the knowledge and skills necessary for future careers in academe or in industrial or national laboratories.