Search for new phases of the exotic superfluid 3He under nanoconfinement

大多数消费品都利用凝聚态物质研究的进步所产生的技术。未来的进步将通过“好奇心驱动”的探索来实现，这种探索只能在实验室环境中进行。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，标志着从所谓的体三维行为到新的二维状态的过渡。本科生和一名博士生将在前沿知识的基础上设计和制造这些结构，开辟量子纳米流体学的新领域。表面必须具有明确定义的平滑度，因为平滑度（可以用氦4涂层改变）会改变表面的散射，就像镜面不同于磨砂表面一样。这种散射特性（连同约束）也可以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。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。该团队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。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（复杂且精确制造的硅腔，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。实验活动将使用输运（超流体密度和热传导性）以及新型噪声测温和纳米线作为局部温度计来探测激发。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。通过测量受限3He的相图，可以绘制出强耦合强度对压力和温度依赖性的细节，从而更可靠地预测受限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。在受限的A相和B相之间的一阶跃迁中的迟滞研究（与整体成核完全不同）将挑战当前对这些量子跃迁的理解。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。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Non-technical AbstractMost consumer items utilize technology that emerged because of advances in condensed matter research. Future advances will be enabled by the sort of “curiosity driven” exploration of new regimes 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 so-called 3 dimensional behavior to a new 2 dimensional regime. Undergraduate students and a Ph.D student will build on cutting edge knowledge to design and fabricate these structures opening up a new area of quantum nano-fluidics. The surfaces will have to have a well-defined smoothness since the smoothness (alterable with a coating of helium 4) changes the scattering at the surface much like a mirrored surface is different from a frosted surface. This scattering quality (together with the confinement) can also change the types of superfluid states (“phases”) that emerge. These phases should show a property “chirality” that should have properties like a spinning top. 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. Past graduate students and undergraduates of this team 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. Technical abstract:Superfluid 3He can inform research activity that extends across many fields in Physics. The project combines nanofluidics (intricate and precisely fabricated silicon 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 novel noise thermometry and a nanowire to act as local thermometers. 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, 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. Studies of the hysteresis in the first-order transition between the confined A and B phases (radically different from nucleation in bulk) will challenge current understanding of these quantum transitions. 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.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.