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

非技术摘要大多数消费品利用由于凝聚态研究的进步而出现的技术。未来的进步将通过对只有在实验室环境中才能获得的新机制的“好奇心驱动”的探索来实现。在该计划中进行的研究将检查超流3 He的特殊性质，当被限制在精确定义的结构中时，高度小于千分之一毫米，标志着从所谓的3维行为到新的2维状态的过渡。本科生和博士生将建立在尖端知识的基础上，设计和制造这些结构，开辟了量子纳米流体的新领域。 表面必须具有明确定义的平滑度，因为平滑度（可通过氦4涂层改变）会改变表面处的散射，就像镜面与磨砂表面不同一样。这种散射性质（连同限制）也可以改变出现的超流状态（“相”）的类型。这些相应该显示出一种“手性”的性质，这种性质应该像一个旋转的陀螺。这些新的阶段应该表现出新的特性，如高导电的“边缘状态”，这是科学上的“令人兴奋的”，并可能在未来形成的基础上的新型设备的计量和计算。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提供具有挑战性的职业生涯。技术摘要：超流体3 He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（复杂而精确制造的硅腔，其尺寸调整到超流体的相干长度的尺度）与低温物理相结合，以揭示新的尺寸效应。实验活动将使用传输（超流密度和热导率）以及新颖的噪声测温法和纳米线作为局部温度计来探测激发。研究人员预计，全新的p波超流态可以通过这种限制来稳定，并且保持（3 He-B）或破坏（3 He-A）时间反演对称性的超流基态之间的平衡也将受到限制的影响。通过测量受限的3 He的相图，强耦合强度的压力和温度依赖性的细节将被绘制出来，允许更可靠的预测3 He的相图下限制。约束也将提供一种方法来研究表面/边缘激发出现的结果，散装/边缘对应。对受限的A和B相之间的一阶跃迁中的滞后现象的研究（与体核化完全不同）将挑战目前对这些量子跃迁的理解。新的几何结构将探索量子传输在单个和多个接口的物理。通过结合低温和纳米制造，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的领导角色做好准备。最终，在约束条件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NSF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.