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

【非技术】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，越来越便宜，越来越快。由于凝聚态物质研究的基本进展，大多数消费品的内置技术得以存在。未来的进步将会发生，因为好奇心驱使探索新的体制，目前只能在实验室环境中获得。在这个项目中进行的研究将检查超流体3He的特殊性质，当被限制在精确定义的小于千分之一毫米高的结构中时，标志着从体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。表面必须有明确的平滑度——表面涂层（在磁场下用纯氦4或氦3）应该改变出现的超流体状态（“相”）的类型。这些相应该表现出“手性”的性质，应该具有旋转陀螺的性质。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过去的研究生和本科生已经在学术界，高科技行业和金融部门从事富有成效的职业，计划中的研究将为新一代学生准备具有挑战性的职业。新的相将揭示系统从近三维材料转变为更二维系统的尺寸范围。这些新相应该表现出新颖的特征，如高导电性的“边缘状态”，这在科学上是“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 .他可以为物理学中许多领域的研究活动提供信息。该项目将纳米流体学（复杂而精确的制造腔体，其尺寸调整到超流体相干长度的规模）与低温物理学相结合，以揭示新的尺寸效应。实验活动将利用输运（超流体密度和导热性）以及一种新型纳米级超细导线来探测激发，该导线可作为局部温度计或光谱仪。研究人员期望通过这种约束可以稳定全新的p波超流体状态，并且保持（3He-B）或破坏（3He-A）时间反转对称的超流体基态之间的平衡也将受到约束的影响。通过测量在外加磁场和没有外加磁场的情况下限制3He的相图，将绘制出强耦合强度对压力和温度依赖的细节，从而更可靠地预测限制下3He的相图。约束也将提供研究由于体/边对应而产生的表面/边激发的手段。此外，这项研究活动将为“实验室中的宇宙学”提供一个新的例子。对受限制的A相和B相之间的一阶跃迁的研究，与整体成核完全不同，将有可能为早期宇宙暴胀时期的过程提供一个模型。新的几何将探索量子在单一和多个界面上传输的物理特性。通过低温和纳米制造的结合，研究生和本科生将接触到令人兴奋的训练场地，这些训练场地已经为科学家在学术界和高科技行业的领导角色做好了准备。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。

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.