Exploring Dynamic Spin Correlations In Nanoscale Structures Via Microwave Transport Spectroscopy

****非技术摘要****现代科学的挑战之一是学习如何控制和操纵基本量子系统，以创造具有扩展功能的电子设备。实现这一目标需要更好地理解受环境强烈影响的小系统在其条件随时间变化时的行为。该奖项支持一个项目，研究一个电子的时间依赖特性，该特性被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。这种排列具有一系列高度普遍的静态特性，这是由于被称为近藤效应的受限电子和离域电子的相干集体行为。该项目将利用有关近藤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。这些知识将有助于在实际相关的非平衡条件下进一步发展简单量子系统的动力学概念。该研究将有利于追求基本量子态相干控制的社区，并补充最近块状材料相关动力学的研究。参与该项目的学生将接受最先进的技术培训，发展研究和关键问题解决和决策技能，为在学术界，工业界和政府的职业生涯做好准备。该项目将为热情的高中生提供研究机会，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****由半导体异质结构中二维电子气体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通用缩放特性和研究近道相关电子的非平衡方面。后者在量子点中是可能的，因为磁性“杂质”附近的局部电场，由点中未配对的电子自旋表示，可以通过在通过隧道屏障连接到点的宏观源极和漏极“引线”之间施加一个小偏置来产生。该个人研究者奖将支持一个项目，将这些研究扩展到一个时间依赖的制度，并通过使量子点受到振荡偏置和/或门电压来研究近藤态的动态特性。该项目的目的是测试可观测特性在频率和近藤温度方面的预测普遍性，重点是光子介导的相关性和耗散之间的相互作用。实验将在GaAs/AlGaAs半导体异质结构上的量子点上进行，实验将在一个特殊构造的设备上进行，该设备允许在可调谐的方向，大小和频率的微波频率场存在下精确测量器件的电导。参与该项目的学生将接受最先进的技术培训，发展研究和关键问题解决和决策技能，为在学术界，工业界和政府的职业生涯做好准备。该项目将为热情的高中生提供研究机会，这将激发他们对研究的兴趣，并邀请他们从事科学事业。

****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.