Mechanical Properties of Quantum Solids: Defects, Deformation and Flow

量子固体的机械特性：缺陷、变形和流动

• 批准号: RGPIN-2017-04285
• 负责人: Beamish, John
• 金额: $ 3.35万
• 依托单位: University of Alberta
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2017
• 资助国家: 加拿大
• 起止时间: 2017-01-01 至 2018-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=633021
• 关键词: Mechanical; Properties; Quantum; Solids; Defects

Solid helium is the epitome of a “quantum solid” - a crystal whose properties are controlled by quantum mechanics. In the absence of external pressure, quantum motion prevents helium from freezing, even at absolute zero. At low temperatures, liquid helium exhibits unusual behavior, including a spectacular phenomenon – “superfluidity” – that allows it to flow with absolutely no dissipation. Helium can be crystallized by applying pressure but its properties are still dominated by quantum effects. One startling prediction is a new phase of matter known as a “supersolid”. In 2004, it appeared that mass decoupling from a torsional oscillator had finally been seen - the expected signature of supersolidity. However, after a decade of intensive effort it has become clear that the torsional oscillator “decoupling” was an artifact, the result of unexpected changes in solid helium’s elastic properties, not a sign of supersolidity. The elastic behavior, dubbed “giant plasticity”, reflects the extraordinary mobility of crystal defects. At very low temperatures dislocations glide freely through

固态氦是“量子固体”的缩影--一种性质由量子力学控制的晶体。在没有外部压力的情况下，量子运动可以防止氦冻结，即使是在绝对零度下。在低温下，液氦表现出不寻常的行为，包括一种壮观的现象-“超流性”-允许它流动而绝对没有耗散。氦可以通过施加压力而结晶，但其性质仍然由量子效应主导。一个令人吃惊的预言是物质的一个新阶段，即所谓的“超固体”。在2004年，人们似乎终于看到了扭转振子的质量解耦--这是超固体的预期特征。 然而，经过十年的密集努力，人们已经清楚地看到，扭转振荡器的“解耦”是一个人为因素，是固体氦的弹性性质发生意外变化的结果，而不是超固体的迹象。这种被称为“巨塑性”的弹性行为反映了晶体缺陷的非凡流动性。在非常低的温度下，位错自由地滑动通过