Experiments in Quantum Solid He-4

量子固体 He-4 实验

• 批准号: 1005325
• 负责人: Haruo Kojima
• 金额: $ 36万
• 依托单位: Rutgers University New Brunswick
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-09-01 至 2014-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1005325&HistoricalAwards=false
• 关键词: Experiments; Quantum; Solid; He

Technical AbstractExperimental evidence has shown that the quantum solid He-4 partially decouples mechanically from its moving container wall. An exciting yet controversial interpretation of these experiments is that the quantum solid He-4 behaves as a superfluid while retaining its crystalline properties. It is generally agreed that the presence of defects such as dislocation lines and grain boundaries is somehow involved. In this project, experiments will be carried out to measure both ultrasonic propagation (for probing the defects) and torsional oscillation (for probing mechanical decoupling) will be simultaneously measured in the identical sample of solid He-4 in order to elucidate the relationship between these two effects. Fourth sound, which propagates in a material only if the material becomes a superfluid, will be searched. A successful observation of fourth sound propagation will supply a definitive evidence for superfluidity of solid He-4. Graduate students and postdoctoral fellows will participate in a truly frontier research of modern condensed matter physics. Undergraduate students will be involved in the research as honors and independent projects. They will all be exposed to the modern technologies in instrumentation, data acquisition and analyses.Non-Technical AbstractUnderstanding how quantum mechanics affects the physical properties of solids is one of the most important goals of solid state physics field. Measured by the degree of delocalization or "fuzziness" of atoms, solid helium at very low temperatures is the substance known in nature most affected by quantum mechanics. It is then crucial in fundamental physics and ultimately in utilization of materials to acquire thorough knowledge of the properties of solid helium. The internal structure such as defects and crystalline faults in solid helium will be measured by non-destructive high frequency ultrasound propagation techniques. This ultrasound probe will be complemented by the measurement of the mechanical response of the same solid to a moving body attached to its surface. Comparison of these two measurements is designed to reveal the origins of quantum mechanical behavior of solid helium and ultimately other solids of technological importance. The exciting fundamental research in the project will be experienced by participating undergraduate and graduate students as well as postdoctoral fellows. All participants will be exposed to the modern technologies in instrumentation, data acquisition and analyses. The research experience will be an excellent training ground in preparation for becoming a part of scientific work force in the U.S.

技术摘要实验证据表明，量子固体He-4与其移动的容器壁存在部分机械解耦。对这些实验的一个令人兴奋但有争议的解释是，量子固体He-4在保持其晶体性质的同时表现得像超流体一样。人们普遍认为，位错线和晶界等缺陷的存在在某种程度上与之有关。在本项目中，实验将在相同的He-4固体样品中同时测量超声波传播（用于探测缺陷）和扭转振荡（用于探测机械解耦），以阐明这两种效应之间的关系。第四种声音，只有当材料变成超流体时才会在材料中传播。第四次声传播的成功观测将为固体氦-4的超流动性提供明确的证据。研究生和博士后将参与现代凝聚态物理的真正前沿研究。本科生将作为荣誉和独立项目参与研究。他们都将接触到仪器仪表、数据采集和分析方面的现代技术。摘要了解量子力学如何影响固体的物理性质是固体物理领域的重要目标之一。通过原子的离域或“模糊”程度来测量，极低温下的固体氦是自然界中已知受量子力学影响最大的物质。因此，在基础物理学和最终的材料利用中，获得固体氦性质的全面知识是至关重要的。利用非破坏性高频超声传播技术测量固体氦的内部结构，如缺陷和晶体缺陷。这种超声波探针将通过测量同一固体对附着在其表面的移动物体的机械响应来补充。这两种测量结果的比较旨在揭示固体氦和其他具有重要技术意义的固体的量子力学行为的起源。项目中令人兴奋的基础研究将由参与的本科生、研究生以及博士后来体验。所有参与者都将接触到仪器仪表、数据采集和分析方面的现代技术。研究经验将是一个很好的训练基地，为成为美国科学工作人员的一部分做准备