Experiments on Superfluid 3He in Bulk and in Aerogel

散装和气凝胶超流体 3He 实验

• 批准号: 0071630
• 负责人: Jeevak Parpia
• 金额: $ 80.35万
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-02-01 至 2005-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0071630&HistoricalAwards=false
• 关键词: Experiments; Superfluid; 3He; Bulk; Aerogel

This research is focused on the investigation of the properties of superfluid 3He in Aerogel. New areas of the phase diagram of superfluid 3He in aerogel will be explored. The Aerogel may potentially offer the possibility of introducing controlled disorder into the liquid to create new physical systems. One project at Cornell will measure the specific heat of 3He in aerogel near the superfluid transition. Another Cornell project will study coherent spin precession in pure 3He under specific field gradient conditions that yield a long-lived homogenous precession mode. A collaboration at the Kapitza Institute in Moscow will examine the feasibility of stabilizing the B phase of 3He in Aerogel, as well as explore the spin dynamics in the presence of disorder. At Delaware, the collaboration will focus on exploring the feasibility of new tailor made aerogels, having correlations that are different from those grown under basic conditions. The Delaware group will also examine the feasibility of subjecting the aerogel to uniaxial compression to alter the density and provide a preferred direction into the aerogel. Theoretical support for these activities will be provided by the group at the Ohio State University and by researchers at the Kapitza Institute. Graduate students and post-doctoral associates involved in this project will be exposed to sensitive signal detection and recovery technology, large scale project design and management as well as a thorough exposure to data acquisition and management. Our substantial involvement in research with colleagues in Russia will provide International perspectives and establish long-term collaborations that are important for the scientific community as a whole. Our training will prepare students and post-docs for academic, technical, and management careers. This work is directed at the study of the superfluid 3He in the presence of disorder. While ordinarily, superfluid 3He is the purest material on earth and supports no disorder or impurities, we have found that the introduction of a dilute nanometer scale structured silica glass allows the properties of the superfluid to be altered in a well-defined way. The changes to the phase diagram, including the ability to support new types of magnetic (spin) transport mechanisms will be explored in this project which is to be carried out at Cornell University in Ithaca, the University of Delaware, the Ohio State University, and at the Kapitza Institute in Moscow. The group will develop and use new magnetic imaging and sonic techniques, and carry out sensitive measurements at ultra-low temperatures. The research should provide information on a potentially new class of three dimensional quantum phase transitions (a quantum phase transition is one in which the fluctuations near the critical point are quantum and not thermal in nature, and quantum phase transitions are thought to be related to the early universe) as well as the transport of spins across interfaces in disordered materials, a problem of considerable technological importance. Students and Post-Doctoral Associates in this program receive rigorous training in physics, signal recovery, data acquisition and management as well as project integration, and can pursue careers in either academic or industrial science. The International aspect of our collaboration also offers unique potential for human resources.

本研究重点研究气凝胶中超流体 3He 的性质。 将探索气凝胶中超流体 3He 相图的新领域。 气凝胶可能提供将受控无序引入液体以创建新物理系统的可能性。康奈尔大学的一个项目将测量气凝胶中超流体转变附近 3He 的比热。康奈尔大学的另一个项目将研究特定场梯度条件下纯 3He 中的相干自旋进动，从而产生长寿命的均匀进动模式。莫斯科卡皮察研究所的一项合作将研究稳定气凝胶中 3He B 相的可行性，并探索无序情况下的自旋动力学。在特拉华州，合作将重点探索新型定制气凝胶的可行性，其相关性不同于在基本条件下生长的气凝胶。 特拉华小组还将研究对气凝胶进行单轴压缩以改变密度并提供进入气凝胶的首选方向的可行性。 俄亥俄州立大学的研究小组和卡皮察研究所的研究人员将为这些活动提供理论支持。参与该项目的研究生和博士后将接触敏感信号检测和恢复技术、大规模项目设计和管理以及全面的数据采集和管理。我们与俄罗斯同事的大量参与研究将提供国际视角并建立对整个科学界都很重要的长期合作。我们的培训将为学生和博士后的学术、技术和管理职业做好准备。这项工作旨在研究存在无序的超流体 3He。虽然通常情况下，超流体 3He 是地球上最纯净的材料，不存在无序或杂质，但我们发现引入稀释的纳米级结构石英玻璃可以以明确的方式改变超流体的特性。该项目将探讨相图的变化，包括支持新型磁（自旋）输运机制的能力，该项目将在伊萨卡康奈尔大学、特拉华大学、俄亥俄州立大学和在莫斯科卡皮察研究所。该小组将开发和使用新的磁成像和声波技术，并在超低温下进行敏感测量。这项研究应该提供有关一类潜在的新型三维量子相变的信息（量子相变是一种临界点附近的波动本质上是量子的而不是热的，并且量子相变被认为与早期宇宙）以及无序材料中自旋跨界面的传输，这是一个具有相当大的技术重要性的问题。 该项目的学生和博士后将接受物理学、信号恢复、数据采集和管理以及项目集成方面的严格培训，并可以从事学术或工业科学领域的职业。我们合作的国际方面也为人力资源提供了独特的潜力。