Theory of Electrons in Solids

该奖项支持凝聚态物理的理论研究。在原子尺度上研究粒子总是有一种特别的魅力，它们的运动受量子理论的支配。在传统的凝聚态物理中，量子特性的表现通常是电子或声子等基本粒子大量聚集的结果。在电子元件的稳步小型化和制造“微观”系统（即接近原子大小）技术的进步的推动下，出现了一种研究趋势，即少数电子的量子效应可以控制人类或其机器替代品可感知的大小系统的动力学结果，技术上称为“宏观”。这种纳米系统，只有几十亿分之一米大小，电子与宏观物体的相互作用形成了这些研究的中心主题，类似于阿基米德承诺的将地球从一个固定的点移动。本项目旨在为量子信息处理和计算以及自旋增强光电子学中的基本器件的构建做出理论贡献。计划研究利用激光操纵半导体纳米结构中的电子及其自旋自由度实现量子算法所涉及的基本物理过程的理论。我们已经在理论上证明，激光束可以产生一种激发，这种激发将旋转量子点中单个电子的自旋，或者打开和关闭两个量子点中两个电子之间的相互作用。这些量子运算是任何量子计算都可能实现的基石，只要有足够的这些带有电子的点。在本研究中，(1)我们通过研究光的纳米共振腔的影响来寻求增强两个电子之间按需相互作用的方法；(2)设计激光脉冲形状来完成量子运算，同时减轻系统其他元素和环境的不良影响；(3)我们理论化了在环境退相干效应存在的情况下，如何详尽地量化由激光引起的两个电子的运动。两个自旋相互作用的量子控制理论的一个衍生是对自旋集合的光学控制，以产生一个可以在10皮秒（10万亿分之一秒）内打开和关闭的磁铁。我们研究了接近半导体异质结构的铁磁体作为电子自旋取向和控制的产生手段。这导致了依赖自旋的电子设备的新功能。对靠近铁磁体界面的半导体中电子自旋输运的详细研究为自旋器件的性能提供了基础。量子运算是基于激光操作的半导体纳米系统的通用、可扩展量子计算机的基础。我们的自旋极化产生和控制方法是自旋电子学的基本要素。这两种方法都是建立在当前技术和工业的优势之上的，但它们在很大程度上偏离了当前的研究方式。它们直接导致了磁光控制测试的建议；构建量子计算机原型的应用；以及低功耗自旋电子器件的设计。这项研究为实验物理学家和工程师团队合作测试和实施这些想法提供了基础，并从互动中受益。我们的首要目标是培养新一代量子科学家和工程师。纳米世界的驯服激发了各个教育水平的年轻人的想象力。该研究的跨学科性质提供了广泛的教育。正在编写一本教科书，以传播量子理论在宏观-微观相互作用中的新重点。工作是通过加州大学圣地亚哥分校加州电信和信息技术研究所完成的，以便与工业界联系。该奖项支持凝聚态物理的理论研究。在原子尺度上研究粒子总是有一种特别的魅力，它们的运动受量子理论的支配。在传统的凝聚态物理中，量子特性的表现通常是电子或声子等基本粒子大量聚集的结果。在电子元件的稳步小型化和制造“微观”系统（即接近原子大小）技术的进步的推动下，出现了一种研究趋势，即少数电子的量子效应可以控制人类或其机器替代品可感知的大小系统的动力学结果，技术上称为“宏观”。这种纳米系统，只有几十亿分之一米大小，电子与宏观物体的相互作用形成了这些研究的中心主题，类似于阿基米德承诺的将地球从一个固定的点移动。本项目旨在为量子信息处理和计算以及自旋增强光电子学（自旋电子学）的基本器件的构建做出理论贡献。量子运算是基于激光操作的半导体纳米系统的通用、可扩展量子计算机的基础。我们的自旋极化产生和控制方法是自旋电子学的基本要素。这两种方法都是建立在当前技术和工业的优势之上的，但它们在很大程度上偏离了当前的研究方式。它们直接导致了磁光控制测试的建议；构建量子计算机原型的应用；以及低功耗自旋电子器件的设计。这项研究为实验物理学家和工程师团队合作测试和实施这些想法提供了基础，并从互动中受益。我们的首要目标是培养新一代量子科学家和工程师。纳米世界的驯服激发了各个教育水平的年轻人的想象力。该研究的跨学科性质提供了广泛的教育。正在编写一本教科书，以传播量子理论在宏观-微观相互作用中的新重点。工作是通过加州大学圣地亚哥分校加州电信和信息技术研究所完成的，以便与工业界联系

This award supports theoretical research in condensed matter physics. There is always a special fascination in the study of particles on the atomic scale where their motion is governed by quantum theory. In traditional condensed matter physics, the manifestation of the quantum properties is usually as a result of an enormous aggregate of elementary particles such as electrons or phonons. Driven by the steady miniaturization of the electronics components and by the advances in the techniques of making "microscopic" systems, i.e., approaching atomic size, a trend of research emerges where the quantum effects of a few electrons can govern the outcome of the dynamics of a system of size perceptible to humans or their machine surrogates, technically designated as "macroscopic." Such interplay of a nano-system, of size of a few billionths of a meter, of electrons with macroscopic objects forms the central theme of these studies, an exercise akin to the promise of Archimedes to move the earth from one firm spot.The aim of this project is theoretical contribution to construction of fundamental devices in quantum information processing and computation and in spin-enhanced optoelectronics. Research is planned on the theory of the basic physical processes involved in the realization of the quantum algorithms by means of laser manipulation of electrons and their spin degrees of freedom in semiconductor nanostructures. We have shown in theory that a laser beam can be made to produce an excitation which will rotate the spin of a single electron in a quantum dot or to switch on and off an interaction between two electrons in two dots. These quantum operations are the building blocks from which any quantum computation is possible given a sufficient set of these dots with electrons in them. In this research, (1) we seek means to enhance the on-demand interaction between two electrons by examining the effect of a nano-resonance cavity of light; (2) we design laser pulse shapes to accomplish the quantum operations, at the same time alleviating the undesired influence of other elements of the system and of the environment; (3) we theorize how to exhaustively quantify the dance of the two electrons set in motion by the laser in the presence of decoherence effects of the environment. A spin-off of the theory of quantum control of the interaction of two spins is the optical control of an ensemble of spins to create a magnet which could be switched on and off within ten picoseconds (ten trillionth of a second).We investigate the proximity of ferromagnets to a semiconductor heterostructure as means of generation of electron spin alignment and control. These lead to new functions of an electronic device dependent on the spin. The detailed study of the electron spin transport in the semiconductor next to the interface with the ferromagnets yields the basis of the spin device performance.The quantum operations are the basis of a universal, scalable quantum computer based on laser-operated semiconductor nanosystems. Our methods of spin polarization generation and control are the basic elements of spintronics. Both approaches are founded on the strengths of current technology and industry and yet they deviate substantially from current research fashion. They lead directly to proposals of tests of optical control of magnetism; applications to building prototype quantum computers; and designs of spintronics devices with low power demand. This research provides the basis for enabling collaborations to test and implement these ideas with groups of experimental physicists and engineers and benefits from the interaction.Foremost in our goal is the education of a new generation of quantum scientists and engineers. The taming of the nanoworld fires the imagination of the young at all education levels. The interdisciplinary nature of the research gives a broad education. A textbook is being written to disseminate the new emphasis of quantum theory in macro-micro interaction. Work is done through the UCSD California Institute for Telecommunication and Information Technology for contact with industry.%%%This award supports theoretical research in condensed matter physics. There is always a special fascination in the study of particles on the atomic scale where their motion is governed by quantum theory. In traditional condensed matter physics, the manifestation of the quantum properties is usually as a result of an enormous aggregate of elementary particles such as electrons or phonons. Driven by the steady miniaturization of the electronics components and by the advances in the techniques of making "microscopic" systems, i.e., approaching atomic size, a trend of research emerges where the quantum effects of a few electrons can govern the outcome of the dynamics of a system of size perceptible to humans or their machine surrogates, technically designated as "macroscopic." Such interplay of a nano-system, of size of a few billionths of a meter, of electrons with macroscopic objects forms the central theme of these studies, an exercise akin to the promise of Archimedes to move the earth from one firm spot.The aim of this project is theoretical contribution to construction of fundamental devices in quantum information processing and computation and in spin-enhanced optoelectronics (spintronics). The quantum operations are the basis of a universal, scalable quantum computer based on laser-operated semiconductor nanosystems. Our methods of spin polarization generation and control are the basic elements of spintronics. Both approaches are founded on the strengths of current technology and industry and yet they deviate substantially from current research fashion. They lead directly to proposals of tests of optical control of magnetism; applications to building prototype quantum computers; and designs of spintronics devices with low power demand. This research provides the basis for enabling collaborations to test and implement these ideas with groups of experimental physicists and engineers and benefits from the interaction.Foremost in our goal is the education of a new generation of quantum scientists and engineers. The taming of the nanoworld fires the imagination of the young at all education levels. The interdisciplinary nature of the research gives a broad education. A textbook is being written to disseminate the new emphasis of quantum theory in macro-micro interaction. Work is done through the UCSD California Institute for Telecommunication and Information Technology for contact with industry.***