Quantum Mechanics of Macroscopic Variables

宏观变量的量子力学

• 批准号: 9876874
• 负责人: Siyuan Han
• 金额: $ 24.1万
• 依托单位: University of Kansas Center for Research Inc
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-07-15 至 2003-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9876874&HistoricalAwards=false
• 关键词: Quantum; Mechanics; Macroscopic; Variables

9876874HanExperiments will be undertaken to explore the quantum mechanical nature of a macroscopic variable -- in this case the magnetic flux F linking a SQUID (a superconducting loop containing a Josephson junction). A particular focus of this work will be to understand the effects of the environment (damping and temperature) on the evolution of F from purely classical to quantum behavior as seen in the switching of the SQUID between two fluxoid wells by tunneling through a potential barrier. The system energy can be quantized into discrete levels within each of these macroscopically distinct fluxoid wells. During tunneling, the magnetic moment of the system flips, changing by about 1010 mB --- a very macroscopic quantity. Thus these experiments will represent a physical realization of the famous Schrodinger's cat paradox resulting from the coherent superposition of macroscopically distinct states. Additionally, the experiments will permit controlled tests of the underlying theory for the interaction of quantum systems with their environment, which is applicable to many physical systems: microscopic as well as macroscopic. This work will be carried out as coupled research projects between SUNY Stony Brook and the University of Kansas. Initially, work at Kansas will focus on development of new microwave techniques for measurement of Rabi oscillations and at Stony Brook on the extension of previous techniques as well as new sample fabrication. Data and analysis will be shared between groups.%%%Experiments will be undertaken to explore the quantum mechanical nature of a macroscopic variable -- in this case the magnetic flux F linking a superconducting loop. A particular focus of this work will be to understand the effects of interactions with surrounding matter on the evolution of F from purely classical to quantum behavior as seen in the switching of the magnetic moment of the loop due to quantum mechanical tunneling. During tunneling, the magnetic moment of the system flips, changing by about ten billion times that of a single electron --- a very macroscopic quantity. Coherent oscillations of the flux will demonstrate purely quantum behavior. Additionally, the experiments will permit controlled tests of the underlying theory for the interaction of quantum systems with their environment, which is applicable to many physical systems: microscopic as well as macroscopic. This work will be carried out as coupled research projects between SUNY Stony Brook and the University of Kansas. Initially, work at Kansas will focus on development of new microwave techniques for measurement of oscillations and at Stony Brook on the extension of previous techniques as well as new sample fabrication. Data and analysis will be shared between groups. Students will receive extensive training both in fundamental physics and a variety of state-of-the-art techniques such as electronic measurements and sample fabrication, which will prepare them for both academic and industrial careers.

9876874Han 将进行实验来探索宏观变量的量子力学性质 - 在本例中是连接 SQUID（包含约瑟夫森结的超导回路）的磁通量 F。这项工作的一个特别重点是了解环境（阻尼和温度）对 F 从纯经典行为到量子行为演化的影响，如 SQUID 通过穿过势垒在两个通量井之间切换时所见。系统能量可以量化为这些宏观上不同的通量井中的每一个内的离散水平。在隧道效应期间，系统的磁矩发生翻转，变化约 1010 mB——这是一个非常宏观的量。因此，这些实验将代表著名的薛定谔猫悖论的物理实现，该悖论是由宏观不同状态的相干叠加引起的。此外，这些实验将允许对量子系统与其环境相互作用的基础理论进行受控测试，该理论适用于许多物理系统：微观和宏观。这项工作将作为纽约州立大学石溪分校和堪萨斯大学之间的联合研究项目进行。最初，堪萨斯大学的工作重点是开发用于测量拉比振荡的新微波技术，石溪分校的工作重点是扩展先前的技术以及新的样品制造。数据和分析将在小组之间共享。%%%将进行实验来探索宏观变量的量子力学本质——在本例中是连接超导回路的磁通量 F。这项工作的一个特别重点是了解与周围物质的相互作用对 F 从纯经典行为到量子行为演化的影响，如量子力学隧道效应引起的环路磁矩的切换所示。在隧道效应期间，系统的磁矩发生翻转，其变化量约为单个电子的一百亿倍——这是一个非常宏观的量。通量的相干振荡将展示纯粹的量子行为。此外，这些实验将允许对量子系统与其环境相互作用的基础理论进行受控测试，该理论适用于许多物理系统：微观和宏观。这项工作将作为纽约州立大学石溪分校和堪萨斯大学之间的联合研究项目进行。最初，堪萨斯大学的工作重点是开发用于测量振荡的新微波技术，石溪分校的工作重点是扩展先前的技术以及新的样品制造。数据和分析将在小组之间共享。学生将接受基础物理学和电子测量和样品制造等各种最先进技术的广泛培训，这将为他们的学术和工业职业生涯做好准备。