Exploring Dynamic Spin Correlations In Nanoscale Structures Via Microwave Transport Spectroscopy

通过微波传输光谱探索纳米级结构中的动态自旋相关性

• 批准号: 0804199
• 负责人: Andrei Kogan
• 金额: $ 33万
• 依托单位: University of Cincinnati Main Campus
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-08-01 至 2012-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0804199&HistoricalAwards=false
• 关键词: Exploring; Dynamic; Spin; Correlations; Nanoscale

****NON-TECHNICAL ABSTRACT****One of the modern challenges of science is to learn how to control and manipulate basic quantum systems in order to create electronic devices with expanded functionalities. Achieving this goal requires an improved understanding of how small systems, which are known to be strongly influenced by their environment, behave when their conditions change over time. This award supports a project to investigate time-dependent properties of an electron confined to a very small region of space and interacting with nearby macroscopic conductors. Such an arrangement possesses a striking array of highly universal static properties due to a coherent collective behavior of the confined and the delocalized electrons referred to as the Kondo effect. The project will capitalize on extensive existing knowledge of the static properties of Kondo-correlated electrons and answer fundamental questions concerning their interaction with electromagnetic fields. Such knowledge will aid further development of concepts in dynamics of simple quantum systems under practically relevant, non-equilibrium conditions. The research will benefit the community pursuing coherent control of elementary quantum states and complement recent studies of correlated dynamics in bulk materials. Students involved in the project will be trained in state-of-the-art technology, develop research and critical problem solving and decision making skills and become prepared for careers in academe, industry and government. The project will generate research opportunities for enthusiastic high-school students, which will stimulate their interest in research and invite them to pursue careers in science.****TECHNICAL ABSTRACT****Controllable quantum dots formed by a lateral confinement of a two-dimensional electron gas in a semiconductor heterostructure have been used in recent years by several groups to test universal scaling properties and investigate non-equilibrium aspects of Kondo-correlated electrons. The latter is possible in a quantum dot because a local electric field near the magnetic "impurity", represented by an unpaired electron spin in the dot, can be created by applying a small bias between the macroscopic source and drain "leads" connected to the dot via tunnel barriers. This individual investigator award will support a project to extend such studies to a time-dependent regime and investigate dynamic properties of the Kondo state by subjecting the quantum dot to an oscillatory bias and /or gate voltage. The objective of the project is to test the predicted universality of observable properties with respect to frequency and the Kondo temperature, with the emphasis on the interplay between photon-mediated correlations and dissipation. Experiments will be performed with quantum dots made on a GaAs/AlGaAs semiconductor heterostructure in a specially constructed apparatus which permits precision measurements of the device conductance in the presence of a microwave-frequency field of tunable orientation, magnitude and frequency. Students involved in the project will be trained in state-of-the-art technology, develop research and critical problem solving and decision making skills and become prepared for careers in academe, industry and government. The project will generate research opportunities for enthusiastic high-school students, which will stimulate their interest in research and invite them to pursue careers in science.

* 非技术摘要 * 科学的现代挑战之一是学习如何控制和操纵基本量子系统，以创建具有扩展功能的电子设备。 实现这一目标需要更好地理解小系统如何受到环境的强烈影响，当它们的条件随着时间的推移而变化时，它们的行为。该奖项支持一个项目，以调查电子的时间依赖性限制在一个非常小的空间区域，并与附近的宏观导体相互作用。这样的安排拥有一个惊人的高度普遍的静态属性，由于一个连贯的集体行为的限制和离域电子被称为近藤效应。该项目将利用Kondo相关电子静态特性的广泛现有知识，并回答有关它们与电磁场相互作用的基本问题。这些知识将有助于进一步发展概念的动力学简单的量子系统在实际相关的，非平衡条件。这项研究将有利于追求基本量子态的相干控制的社区，并补充了最近对大块材料相关动力学的研究。参与该项目的学生将接受最先进技术的培训，发展研究和关键问题解决和决策技能，并为企业，工业和政府的职业生涯做好准备。该项目将为热情的高中生创造研究机会，这将激发他们对研究的兴趣，并邀请他们从事科学事业。技术摘要 **** 通过半导体异质结构中的二维电子气的横向限制形成的可控量子点近年来已被几个小组用于测试普遍的标度特性和研究近藤相关电子的非平衡方面。后者在量子点中是可能的，因为通过在经由隧道势垒连接到量子点的宏观源极和漏极“引线”之间施加小的偏压，可以在磁性“杂质”附近产生局部电场，该局部电场由量子点中的未成对电子自旋表示。该个人研究者奖将支持一个项目，将这些研究扩展到时间依赖的制度，并通过使量子点受到振荡偏置和/或栅极电压来研究近藤态的动态特性。 该项目的目的是测试预测的普遍性，可观察到的属性与频率和近藤温度，重点是光子介导的相关性和耗散之间的相互作用。实验将进行量子点上的GaAs/AlGaAs半导体异质结在一个特殊构造的设备，允许在可调的方向，幅度和频率的微波频率场的存在下的设备电导的精确测量。参与该项目的学生将接受最先进技术的培训，发展研究和关键问题解决和决策技能，并为企业，工业和政府的职业生涯做好准备。该项目将为热情的高中生创造研究机会，这将激发他们对研究的兴趣，并邀请他们从事科学事业。