Materials World Network: Nearly Two Dimensional 3He- A New Model Quantum System

材料世界网：近二维3He——一种新模型量子系统

• 批准号: 0806629
• 负责人: Jeevak Parpia
• 金额: $ 54万
• 依托单位: Cornell University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-07-01 至 2011-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0806629&HistoricalAwards=false
• 关键词: Materials; World; Network; Nearly; Two

Technical AbstractThis Materials World Network award by the Division of Materials Research supports a three-year experimental program to investigate how reducing the dimensionality of 3He leads to novel p-wave order parameters when this unconventionally paired superfluid is confined to a length comparable to the coherence length. In contrast to metallic systems, 3He has a spherical Fermi surface; yet anisotropic paired states emerge from the isotropic normal liquid. Confinement of 3He in small geometries is expected to modify this behavior. It has been theoretically predicted that confined superfluid 3He will exhibit broken translational symmetry en route to the destruction of superfluidity. Dimensional constraints might also promote the stability of competing phases that are not manifest in the bulk. The technology to fabricate confining geometries with well characterized surfaces that can be patterned to achieve specified roughness has been developed at Cornell University. The roughness will affect the resulting phases via their stability and response to disorder ? an important feature that has implications for the broader relevance of this work to Condensed Matter Physics. Patterning to introduce periodicity and test the robustness of emerging phases of confined 3He against periodicity is also planned. We will also construct and use high precision flow cells to examine flow of 4He, 3He doped 4He films and eventually superfluid 3He in nanoporous media. These demanding experiments, which require development of new techniques, provide a challenging environment where graduate and undergraduate students acquire skills (the ability to innovate, initiate, design and carry out) as well as become familiar with analytic and display tools to prepare them for careers in the Nation's scientific and technological infrastructure. The research program will be integrated with partner programs at Royal Holloway University of London and Manchester University. Graduate students will have the opportunity to work with their counterparts by spending a semester in the UK and by hosting counterparts at Cornell. The research program will also incorporate an undergraduate student throughout the award period.Non-Technical AbstractHelium (unlike all other elements) is inherently quantum-mechanical and does not solidify (unless compressed) even down to absolute zero temperature. It is one of the purest materials that can be prepared by any means, since at these temperatures, impurities simply freeze out during the procedures required to obtain the liquid state. Eventually 3He attains a highly ordered state: superfluidity, which is different from that attained in most superconductors and its sister isotope 4He. The magnetism of the superfluid atoms means that the atoms pair up together and undergo orbital motion exhibiting different phases. These behaviors are affected by confining 3He within precisely characterized geometries that effectively alter the dimensionality of the 3He. By carrying out precise measurements on these systems the research will add to our understanding of the role of confinement under less extreme conditions. The program will also prepare graduate students for an increasingly international scientific and technological environment by embedding them in (and allowing them to host students from) counterpart laboratories that use different techniques to probe the same systems. Besides adding to the understanding of quantum systems, this research provides a demanding experimental environment that educates and trains graduate and undergraduate students for successful careers in the Nation's scientific and technological infrastructure. In addition, this research program will also create a positive impact on future science and technology workforce by involving a science teacher in this research during summer.

技术摘要材料研究部颁发的材料世界网络奖支持一项为期三年的实验计划，以研究当这种非常规配对超流体被限制在与相干长度相当的长度时，如何降低 3He 的维数从而产生新颖的 ​​p 波阶参数。与金属系统相比，3He 具有球形费米面；然而，各向异性配对态是从各向同性正常液体中出现的。将 3He 限制在较小的几何形状中有望改变这种行为。理论上预测，受限超流体 3He 将在超流性破坏的过程中表现出破缺的平移对称性。尺寸限制还可能促进大量不明显的竞争相的稳定性。康奈尔大学开发了一种制造具有良好特征表面的限制几何形状的技术，这些几何形状可以通过图案化来实现指定的粗糙度。粗糙度会通过其稳定性和对无序的响应来影响所得相？这是一项重要特征，它对这项工作与凝聚态物理的更广泛相关性产生了影响。还计划进行图案化以引入周期性并测试受限 3He 新兴相对周期性的鲁棒性。 我们还将构建并使用高精度流动池来检查 4He、3He 掺杂 4He 薄膜以及最终超流体 3He 在纳米多孔介质中的流动。这些要求很高的实验需要开发新技术，为研究生和本科生提供了一个具有挑战性的环境，让他们获得技能（创新、发起、设计和实施的能力），并熟悉分析和展示工具，为他们的职业生涯做好准备。国家科学技术基础设施。该研究项目将与伦敦大学皇家霍洛威学院和曼彻斯特大学的合作伙伴项目整合。研究生将有机会在英国度过一个学期并在康奈尔大学接待同行，从而有机会与同行合作。该研究项目还将在整个奖励期间纳入一名本科生。非技术摘要氦（与所有其他元素不同）本质上具有量子力学，即使在绝对零温度下也不会凝固（除非压缩）。它是可以通过任何方式制备的最纯净的材料之一，因为在这些温度下，杂质在获得液态所需的过程中简单地冻结出来。最终 3He 达到了高度有序的状态：超流动性，这与大多数超导体及其姐妹同位素 4He 所达到的状态不同。超流体原子的磁性意味着原子配对在一起并进行轨道运动，呈现出不同的相位。这些行为受到将 3He 限制在精确表征的几何形状内的影响，这些几何形状有效地改变了 3He 的维度。通过对这些系统进行精确测量，这项研究将加深我们对不太极端条件下限制作用的理解。该计划还将让研究生进入（并允许他们接待来自）使用不同技术探测相同系统的对应实验室（并允许他们接待来自该实验室的学生），为研究生适应日益国际化的科学技术环境做好准备。除了增加对量子系统的理解之外，这项研究还提供了一个要求严格的实验环境，可以教育和培训研究生和本科生，使其在国家科技基础设施中取得成功的职业生涯。此外，该研究项目还将通过让一名科学教师在夏季参与这项研究，对未来的科学和技术劳动力产生积极影响。