SGER: An Experiment to Understand the Apparent "Supersolid" Behavior of Solid 4He

SGER：了解固体 4He 表面“超固体”行为的实验

• 批准号: 0650092
• 负责人: Robert Hallock
• 金额: --
• 依托单位: University of Massachusetts Amherst
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2006
• 资助国家: 美国
• 起止时间: 2006-12-01 至 2009-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0650092&HistoricalAwards=false
• 关键词: SGER; Experiment; Understand; Apparent; Supersolid

********NON-TECHNICAL ABSTRACT*****Recently a startling discovery was announced: At very low temperatures and elevated pressures atoms of helium apparently flow though solid helium without friction. This announcement was startling because ordinary solids behave themselves and while atoms in a solid wiggle a bit, they generally stay put. It is common experience that when you pick up a rock, none of the solid leaks out. This Small Grant for Exploratory Research (SGER) will support a project that will, under a variety of temperatures and pressures, explore whether a pressure difference applied between two liquid helium reservoirs on either side of a block of solid helium will relax by the flow of atoms through the solid helium. The reservoirs on either side of the solid will be liquid, maintained in that state by the unique properties of helium in a highly porous material. If atoms do indeed flow through the solid, this research will help to determine the true mechanism by which this takes place. And, if such flow is present, other experiments will attempt to cause the flow to take place through a donut-shaped sample of solid helium and determine whether such flow is persistent - i.e. able to flow in a closed loop without slowing down. That is, the research will explore whether it is possible for there to be friction-free super-flow in a solid. The experiments are time-urgent since this area is extremely active; with groups around the world intensely pursuing different approaches in attempts to confirm the existence of this strange state. While ripe for discovery, such work is also risky, with some experiments to date yielding unexpected negative results. Confirming the existence of this strange solid would have a large impact our understanding of "quantum states of matter." Graduate students will be involved in the experiments and thus they will receive training that will lead to a Ph.D. and their eventual entry into the scientific workforce.******** TECHNICAL ABSTRACT*****This SGER supports research seeking to provide substantial insight into the true physics behind the startling observations of Kim and Chan seen in solid helium in which they observed a moment of inertia change in a torsional oscillator and interpreted the observation as evidence for a new state of matter, a "supersolid". The first experiments will place solid helium adjacent to helium contained in the porous material Vycor, by which it is possible to create a condition in which liquid helium can interface solid helium at pressures above the normal melting curve. The experiments will seek to establish whether a pressure difference imposed between the two fluid reservoirs on two sides of a cylinder of solid helium can relax by the flow of helium atoms through the solid and how such flow may vary with the base pressure of the solid. When completed, these experiments should shed considerable insight into the true nature of the "supersolid" and help to elucidate the specific mechanism by which such flow takes place. If such flow is detected with reasonable critical velocity, the next experiments will seek to establish a persistent flow in a torus-shaped geometry and document that the flow is indeed persistent. The experiments are time-urgent since this area is extremely active; with groups around the world intensely pursuing different approaches in attempts to confirm the existence of the "supersolid" state. While ripe for discovery, such work is also risky, with some experiments to date yielding unexpected negative results. Confirming the existence of a "supersolid" state would have a large impact on our understanding of quantum states of matter. Graduate students will be involved in the experiments and thus they will receive training that will lead to a Ph.D. and their eventual entry into the scientific workforce.

********* 非技术摘要 ***** 最近宣布了一项惊人的发现：在极低的温度和升高的压力下，氦原子显然可以毫无摩擦地流过固体氦。 这一宣布令人震惊，因为普通固体会表现出自己的行为，尽管固体中的原子会稍微摆动，但它们通常会保持不变。 这是常见的经验，当你拿起一块石头，没有固体泄漏出来。 这个探索性研究（SGER）的小补助金将支持一个项目，该项目将在各种温度和压力下，探索在一块固体氦的两侧的两个液氦储存器之间施加的压力差是否会因原子通过固体氦的流动而放松。 固体两侧的储存器将是液体，通过高度多孔材料中氦的独特性质保持在这种状态。如果原子确实流过固体，这项研究将有助于确定这种情况发生的真正机制。 而且，如果存在这样的流动，其他实验将试图使流动发生通过固体氦的甜甜圈形状的样品，并确定这种流动是否是持久的-即能够在闭环中流动而不减速。也就是说，这项研究将探索固体中是否可能存在无摩擦的超流。这些实验是时间紧迫的，因为这个领域非常活跃;世界各地的研究小组都在积极寻求不同的方法，试图证实这种奇怪状态的存在。 虽然发现的时机已经成熟，但这样的工作也是有风险的，迄今为止的一些实验产生了意想不到的负面结果。 证实这种奇怪固体的存在将对我们对“物质的量子态”的理解产生巨大影响。“研究生将参与实验，因此他们将接受培训，这将导致博士学位。以及他们最终进入科学劳动力市场。技术摘要 * 这个SGER支持的研究旨在为Kim和Chan在固体氦中观察到的惊人观察背后的真实物理学提供实质性见解，他们在固体氦中观察到扭转振荡器中的转动惯量变化，并将该观察结果解释为一种新物质状态（“超固体”）的证据。 第一个实验将把固体氦放置在多孔材料Vycor中所含的氦附近，通过这种方法，可以创造一种条件，在这种条件下，液氦可以在高于正常熔化曲线的压力下与固体氦接触。 这些实验将试图确定在固体氦圆柱体两侧的两个流体储存器之间施加的压力差是否可以通过氦原子流过固体而放松，以及这种流动如何随着固体的基础压力而变化。 完成后，这些实验应该会对“超固体”的真实性质有相当深入的了解，并有助于阐明这种流动发生的具体机制。 如果这种流动被检测到具有合理的临界速度，接下来的实验将寻求在环形几何形状中建立持续流动，并记录该流动确实是持续的。 实验是时间紧迫的，因为这个领域是非常活跃的;世界各地的团体都在积极追求不同的方法，试图证实“超固体”状态的存在。 虽然发现的时机已经成熟，但这样的工作也是有风险的，迄今为止的一些实验产生了意想不到的负面结果。 证明“超固态”的存在将对我们理解物质的量子态产生巨大影响。 研究生将参与实验，因此他们将接受培训，这将导致博士学位。以及他们最终进入科学劳动力市场。