Nanoconfinement, nanofluidics, new phases and their transitions for superfluid 3He

超流体 3He 的纳米限制、纳米流体、新相及其转变

基本信息

批准号：
1708341
负责人：
Jeevak Parpia
金额：
$ 56.8万
依托单位：
Cornell University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2017
资助国家：
美国
起止时间：
2017-06-01 至 2021-05-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1708341&HistoricalAwards=false
关键词：
Nanoconfinement nanofluidics new phases their

项目摘要

Non-Technical AbstractThe pace of research and development is accelerating. Our everyday devices are ever more capable, cheaper, and faster. Most of these consumer items' inbuilt technology exists because of fundamental advances in condensed matter research. Future advances will happen because of curiosity driven exploration of new regimes presently accessible only in a laboratory environment. The research to be conducted in this program will examine the special properties of superfluid 3He when confined in precisely defined structures less than a thousandth of a millimeter tall, marking the transition from bulk three-dimensional behavior to a new two-dimensional regime. Undergraduate students and Ph.D students will design and fabricate these structures opening up a new area of quantum nano-fluidics. The surfaces will have to have a well-defined smoothness - and the surface coating (with pure helium 4 or helium 3 under a magnetic field) should alter the types of superfluid states ("phases") that emerge. These phases should show a property "chirality" that should have properties like a spinning top. Further, the conversion from one state to another ("phase transition") should reveal whether models of the early universe (important for our understanding of the evolution of the universe) can be tested in the laboratory. Past graduate students and undergraduates working with this research group have gone on to productive careers in academia, high-technology industries and the financial sector, and the planned research will prepare a new generation of students for challenging careers. The size range where the system transforms from a nearly three-dimensional material to a more two-dimensional system will be revealed by new phases. These new phases should exhibit novel characteristics such as highly conducting "edge states" that are scientifically "exciting" and that could, in the future form the basis of new types of devices for metrology and computation. Technical abstract:Superfluid 3He can inform research activity that extends across many fields in Physics. The project combines nanofluidics (intricate and precisely fabricated cavities with sizes tuned to the scale of the superfluid's coherence length) with low temperature physics, to expose new size effects. The experimental activity will probe excitations using transport (superfluid density and heat conductivity) as well as a novel nanoscale ultra-fine wire to act as a local thermometer or spectrometer. Researchers expect that entirely new p-wave superfluid states can be stabilized by such confinement and the balance between the superfluid ground state that preserves (3He-B) or breaks (3He-A) time reversal symmetry will also be affected by confinement. By measuring the phase diagram of confined 3He both with and without an applied magnetic field, details of the pressure and temperature dependence of the strong coupling strength will be mapped out allowing for more reliable prediction of the phase diagrams of 3He under confinement. Confinement will also provide the means to study the surface/edge excitations emerging as a result of bulk/edge correspondence. Furthermore this research activity will provide a new example of "cosmology in the laboratory". Studies of the first-order transition between the confined A and B phases, radically different from nucleation in bulk, will potentially provide a model of processes during the inflationary epoch of the early universe. New geometries will explore the physics of quantum transport across single and multiple interfaces. By combining low temperatures and nano fabrication, graduate students and undergraduates will be exposed to the exciting training ground that has prepared scientists for lead roles in academia and high-technology industries. Eventually, the new superfluids that emerge under confinement might be of interest in quantum computation.

非技术摘要研究和开发的步伐正在加快。我们的日常设备功能越来越强大、价格越来越便宜、速度越来越快。大多数消费品的内置技术之所以存在，是因为凝聚态物质研究取得了根本性的进步。由于好奇心驱动对目前只能在实验室环境中才能实现的新机制的探索，未来的进步将会发生。该项目将进行的研究将检验超流体 3He 在被限制在高度小于千分之一毫米的精确定义的结构中时的特殊性质，标志着从大块三维行为到新的二维状态的转变。本科生和博士生将设计和制造这些结构，开辟量子纳米流体学的新领域。表面必须具有明确的光滑度 - 并且表面涂层（在磁场下使用纯氦 4 或氦 3）应该改变出现的超流体状态（“相”）的类型。这些相应表现出“手性”属性，应具有像陀螺一样的属性。此外，从一种状态到另一种状态的转换（“相变”）应该揭示早期宇宙的模型（对于我们理解宇宙的演化很重要）是否可以在实验室中进行测试。与该研究小组合作的往届研究生和本科生已在学术界、高科技行业和金融领域从事富有成效的职业，计划中的研究将为新一代学生做好迎接具有挑战性的职业的准备。系统从近三维材料转变为二维系统的尺寸范围将通过新的相来揭示。这些新相应该表现出新颖的特征，例如高度导电的“边缘态”，这些特征在科学上是“令人兴奋的”，并且可以在未来形成新型计量和计算设备的基础。技术摘要：超流体 3他可以为跨越物理学许多领域的研究活动提供信息。该项目将纳米流体学（复杂且精确制造的腔体，其尺寸调整为超流体相干长度的尺度）与低温物理学相结合，以揭示新的尺寸效应。实验活动将利用传输（超流体密度和热导率）以及用作局部温度计或光谱仪的新型纳米级超细线来探测激发。研究人员预计，全新的p波超流体态可以通过这种限制来稳定，并且保持（3He-B）或破坏（3He-A）时间反演对称性的超流体基态之间的平衡也将受到限制的影响。通过测量有和没有施加磁场的约束 3He 相图，将绘制出强耦合强度的压力和温度依赖性的详细信息，从而可以更可靠地预测约束下 3He 的相图。限制还将提供研究由于体/边缘对应而出现的表面/边缘激励的方法。此外，这项研究活动还将提供“实验室宇宙学”的新范例。对受限 A 相和 B 相之间的一阶转变的研究与整体成核完全不同，将有可能提供早期宇宙暴胀时期过程的模型。新的几何结构将探索跨单个和多个界面的量子传输的物理原理。通过将低温和纳米制造相结合，研究生和本科生将接触到令人兴奋的训练场，为科学家在学术界和高科技行业发挥领导作用做好准备。最终，在约束下出现的新超流体可能会引起量子计算的兴趣。