Fourth Sound Propagation in Supersolid Helium 4

超固体氦中的第四声传播 4

• 批准号: 0704120
• 负责人: Haruo Kojima
• 金额: --
• 依托单位: Rutgers University New Brunswick
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2007
• 资助国家: 美国
• 起止时间: 2007-09-01 至 2011-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0704120&HistoricalAwards=false
• 关键词: Fourth; Sound; Propagation; Supersolid; Helium

****NON-TECHNICAL ABSTRACT****It might seem extremely odd that a rigid solid behaves as a superfluid, which can flow without friction. Nevertheless, such a "supersolid" has been theoretically predicted to exist. All prior attempts to find such a solid have failed. Recently, experiments with a special cylindrical pendulum containing pressurized solid helium-4 showed that the solid apparently partially separates from its container wall. An exciting but controversial interpretation is that the experiments provide evidence for the long-sought supersolid. If the interpretation is confirmed, it presents an entirely new view of the physical solid state. It is thus of paramount importance to furnish an independent and conclusive proof for supersolidity. A unique wave propagation known as "fourth sound" can propagate in a material if and only if it becomes a superfluid. This project will search for just such wave propagation in solid helium-4 at ultra low temperatures. If the wave is found, the supersolidity in helium-4 will be confirmed. It will then become a new probe for measuring the properties of this interesting material and open up a new field of solid state physics. The undergraduate and graduate students as well as postdoctoral fellows participating in this project will experience the excitement of fundamental research. 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.**** TECHNICAL ABSTRACT****Recent torsional oscillator experiments on the quantum solid He-4 below 200 mK indicate that the solid partially decouples from its moving container wall. An exciting but controversial interpretation of these experiments is that the solid He-4 behaves as a superfluid while retaining its crystalline properties. In this project, new fourth sound wave propagation will be searched for in the low temperature solid He-4 using the techniques of superconducting quantum interference device. Fourth sound can propagate in a material if and only if the material becomes a superfluid. A successful observation of fourth sound propagation will supply the definitive and important proof of superfluidity of solid He-4. It will provide an independent probe for measuring the superfluid fraction, thermal and mechanical properties. 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.

****非技术抽象****刚性的固体表现为超级流体，这似乎无摩擦似乎是非常奇怪的。 然而，理论上预测存在这样的“超olid”。 所有先前发现这种稳固的尝试都失败了。 最近，使用含有加压固体氦4的特殊圆柱摆的实验表明，固体显然部分与其容器壁分离。 一个令人兴奋的但有争议的解释是，实验为长期超过的超酚提供了证据。 如果确认了解释，它将给物理固态提供全新的看法。 因此，为Supersolives提供独立和确定的证据至关重要。 只有当它变成超氟时，一个独特的波传播称为“第四声音”才能在材料中传播。 该项目将在超低温度下仅在固体氦4中搜索这种波传播。 如果发现波浪，则将确认氦4中的超压相。 然后，它将成为测量这种有趣材料的特性并打开固态物理学的新领域的新探测器。 本科生和研究生以及参与该项目的博士后研究员将感到基本研究的兴奋。所有参与者将接触到仪器，数据获取和分析方面的现代技术。 研究经验将是准备成为美国科学劳动力的一部分的良好培训场。 对这些实验的一种令人兴奋但有争议的解释是，固体HE-4在保留其结晶特性的同时表现为超氟。在这个项目中，将使用超导量子干扰装置的技术在低温固体HE-4中搜索新的第四波浪传播。 仅当材料变成超氟时，第四声音才能在材料中传播。 成功观察第四张声音传播将提供固体HE-4超流体的确定和重要证明。 它将提供一个独立的探针，用于测量超流体分数，热和机械性能。 研究生和博士后研究员将参加现代冷凝物理物理学的真正边界研究。 本科生将作为荣誉和独立项目参与研究。 他们将全部接触到仪器，数据获取和分析中的现代技术。