Quantum Coherence and Tunneling in Semiconductor Nanostructures

半导体纳米结构中的量子相干性和隧道效应

• 批准号: 0203679
• 负责人: Woowon Kang
• 金额: $ 31.69万
• 依托单位: University of Chicago
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-09-01 至 2006-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0203679&HistoricalAwards=false
• 关键词: Quantum; Coherence; Tunneling; Semiconductor; Nanostructures

This work focuses on the study of phase coherent properties of low-dimensional tunnel junctions and tunable semiconductor quantum dots. These systems juxtapose competing zero-, one- and two-dimensional states separated by a precise, nanometer-scale barriers. Quantum tunneling mixes and enhances the coupling between the degenerate ground states, leading to potential development of long-lived quantum coherence in nanometer scale devices. Precise control and detection of quantum states within solid-state environment remain important challenges in condensed matter physics today. The development of macroscopic quantum coherence in these systems arises from quantum phase transitions that break the underlying symmetry. The underlying physics of phase coherent systems in nanostructured environment is largely unexplored, the dominant decoherent mechanisms unknown, and no detailed theoretical model is currently available. A series of electrical, tunneling, and dynamical measurements to study the quantum coherent transport of electrons in nanometer-scale semiconductor devices is proposed. An important feature of the work is fabrication and characterization of tunnel junctions with barriers down to few lattice spacings. Undergraduate and graduate students involved in the project will receive training in the state of art fabrication and characterization techniques. This training is intended to prepare them for careers in academe, industry or government.This research is centered on the study of quantum coherent phenomena arising from quantum mechanical interplay of electrons in nanometer-scale semiconductor devices. Quantum mechanical coherence is normally difficult to sustain for extended period of time because of coupling to the external perturbations and presence of imperfections. The quantum coherence in these systems derives from recent advances in fabrication of semiconductor nanostructures. In these unprecedentedly clean systems, theories predict quantum phase transitions into novel collective states that can sustain exceptionally long-lived excitations. Electrical and high frequency measurements designed to probe and characterize the postulated quantum states are proposed. Control and manipulation of quantum states can be exploited for applications in quantum information processing, a field of increasing technological importance. Potential applications include quantum computation, quantum cryptography, and test of Einstein-Podolsky-Rosen (EPR) paradox within a solid state environment. Undergraduate and graduate students participating in this research receive broad training in the state of art fabrication and characterization techniques and can pursue careers in industrial or fundamental research.

本工作主要研究低维隧道结和可调谐半导体量子点的位相相干特性。这些系统将相互竞争的零维、一维和二维态并列在一起，由精确的纳米级势垒隔开。量子隧道混合并增强了简并基态之间的耦合，导致了纳米器件中长寿命量子相干的潜在发展。对固体环境中量子态的精确控制和检测仍然是当今凝聚态物理学的重要挑战。在这些系统中，宏观量子相干性的发展源于破坏基本对称性的量子相变。纳米结构环境中位相相干系统的基本物理机制尚不清楚，主要的退相干机制尚不清楚，目前还没有详细的理论模型。提出了一系列用于研究电子在纳米级半导体器件中量子相干输运的电学、隧穿和动力学测量方法。这项工作的一个重要特点是制作和表征具有极小晶格间距的势垒的隧道结。参与该项目的本科生和研究生将接受最先进的制造和表征技术方面的培训。这项培训旨在为他们在学术界、工业界或政府部门的职业生涯做准备。这项研究的中心是研究纳米级半导体器件中电子的量子力学相互作用所产生的量子相干现象。由于与外部扰动的耦合和缺陷的存在，量子力学的相干性通常很难维持很长一段时间。这些系统中的量子相干源于半导体纳米结构制备的最新进展。在这些史无前例的清洁系统中，理论预测量子相变到新的集体状态，可以维持异常长时间的激发。提出了用于探测和表征假设量子态的电学和高频测量。量子态的控制和操纵可用于量子信息处理，这是一个日益重要的技术领域。潜在的应用包括量子计算、量子密码学和在固态环境中测试爱因斯坦-蒲多尔斯基-罗森(EPR)悖论。参与这项研究的本科生和研究生接受了最先进的制造和表征技术方面的广泛培训，并可以在工业或基础研究领域从事职业生涯。