Topological mesoscopic superfluidity of 3He

3He的拓扑介观超流性

• 批准号: EP/R04533X/1
• 负责人: John Saunders
• 金额: $ 179.19万
• 依托单位: Royal Holloway University of London
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2018
• 资助国家: 英国
• 起止时间: 2018 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=EP%2FR04533X%2F1
• 关键词: Topological; mesoscopic; superfluidity; 3He

Helium remains liquid down to the absolute zero of temperature through a combination of relatively weak interatomic interactions and quantum zero point motion. It provides models for studying systems of strongly interacting bosons (4He) and fermions (3He). These materials have played a key role in the development of concepts central to condensed matter physics: Bose-Einstein condensation; macroscopic quantum physics; topological phase transitions; the Landau Fermi liquid theory of electrons in metals; unconventional superconductivity; topological quantum matter. The richest system is superfluid 3He (recognized in the 1996 and 2003 Nobel Prizes), the conceptual reach of which is described by Volovik in terms of a "3He-centric universe", conceptually linked to most major fields of physics.Condensed matter systems feature in every modern technology. The development of this technology has relied on the discovery and creation of new materials with new phases and often unanticipated properties, as well as hybrid devices which combine these materials, increasingly on the nanoscale. Recently the understanding of new phases solely in terms of symmetry breaking has been shown to be inadequate in some cases. This is the notion of topological quantum matter (2016 Nobel Prize). Two important classes of quantum matter are at the centre of attention: topological insulators and topological superconductors. Usual insulators do not conduct electricity, because of an energy gap between filled and empty energy bands. But in a topological insulator the momentum space topology of the band structure necessarily gives rise to conducting surface excitations. On the other hand, as a metal is cooled into its superconducting state, a gap emerges. Topological superconductors also support surface/edge excitations, and there are substantial efforts to identify materials that are bulk topological superconductors.This project will exploit superfluid 3He, known to support two distinct topological superfluid phases in bulk, establishing the new research direction of topological mesoscopic superfluidity. Under nanoscale confinement, this material provides a unique model for topological superconductivity. The subtle interplay between symmetry and topology in these materials is an open question. Our approach will be to confine 3He in precisely engineered geometries to create hybrid nanostructures, allowing a degree of control that is unprecedented. Confinement and periodic structures, with liquid pressure as a tuning parameter of Cooper pair diameter, will induce new superfluid phases, for which the order parameter symmetry will be inferred from nuclear magnetic resonance. These materials will be building blocks for hybrid mesoscopic superfluid systems. Excitations emerge at surfaces/edges/interfaces of the topological superfluid. As well as the interface with inert matter, where we can tune surface scattering in situ, stepped confinement in hybrid structures will create intra-fluid interfaces of the highest quality. Surface and edge spin currents in time reversal invariant superfluid 3He-B will be investigated by NMR and their coupling to confined Anderson-Higgs order parameter collective modes, as well as nano-wires of diameter similar to that of Cooper pairs. Our ambition is to detect non-local response of the surface Majorana modes. Edge states in chiral superfluid 3He-A will be investigated by a predicted anomalous Hall effect in mass and thermal transport. Interface states will be investigated by thermal transport. This project has a strong international collaborative dimension, including partnerships with Cornell, NIST and PTB (Berlin). Partnerships with theorists from the USA, Europe and Japan are central to the design and interpretation of experiments. Partnerships within the scientific instruments industry will deliver short-medium term impact from the technical developments central to this project.

氦在绝对零度下保持液态，这是由于相对较弱的原子间相互作用和量子零点运动的结合。它为研究强相互作用玻色子（4 He）和费米子（3 He）系统提供了模型。这些材料在凝聚态物理学的核心概念发展中发挥了关键作用：玻色-爱因斯坦凝聚;宏观量子物理学;拓扑相变;金属中电子的朗道费米液体理论;非常规超导性;拓扑量子物质。最丰富的系统是超流3 He（在1996年和2003年诺贝尔奖中获得认可），其概念范围由Volovik描述为“3 He中心宇宙”，在概念上与大多数主要物理学领域相关联。凝聚态系统在每一个现代技术中都很重要。该技术的发展依赖于发现和创造具有新相和通常未预料到的性质的新材料，以及越来越多地在纳米级上结合这些材料的联合收割机的混合装置。最近，在某些情况下，仅仅根据对称性破缺来理解新相已经被证明是不够的。这就是拓扑量子物质的概念（2016年诺贝尔奖）。两类重要的量子物质是人们关注的焦点：拓扑绝缘体和拓扑超导体。由于充满的能带和空的能带之间有一个能隙，所以绝缘体不导电。但是在拓扑绝缘体中，能带结构的动量空间拓扑必然会引起传导表面激发。另一方面，当金属冷却到超导状态时，就会出现一个能隙。拓扑超导体也支持表面/边缘激发，并且有大量的努力来识别材料是块体拓扑超导体。本项目将利用超流3 He，已知在块体中支持两种不同的拓扑超流相，建立拓扑介观超流的新研究方向。在纳米尺度的限制下，这种材料为拓扑超导提供了一个独特的模型。在这些材料中，对称性和拓扑结构之间微妙的相互作用是一个悬而未决的问题。我们的方法是将3 He限制在精确设计的几何形状中，以创建混合纳米结构，从而实现前所未有的控制程度。以液体压力作为库珀对直径的调节参数，约束和周期性结构将诱导新的超流相，其序参量对称性将由核磁共振推断。这些材料将是混合介观超流体系统的基石。激发出现在拓扑超流体的表面/边缘/界面。以及与惰性物质的界面，在那里我们可以在原位调整表面散射，混合结构中的阶梯式限制将创建最高质量的流体内界面。本文将通过核磁共振及其与受限的Anderson-Higgs序参量集体模的耦合，以及与库珀对直径相似的纳米线，研究时反不变超流体3 He-B中的表面和边缘自旋电流。我们的目标是检测表面Majorana模式的非本地响应。本文将利用反常霍尔效应研究手征超流体3 He-A的边缘态。界面状态将通过热输运来研究。该项目具有强大的国际合作层面，包括与康奈尔大学，NIST和PTB（柏林）的合作伙伴关系。与来自美国，欧洲和日本的理论家的伙伴关系是实验设计和解释的核心。科学仪器行业内的合作伙伴关系将从对本项目至关重要的技术发展中产生中短期影响。

项目成果

Superfluid Optomechanics with Phononic Nanostructures

具有声子纳米结构的超流体光力学

• DOI: 10.48550/arxiv.2012.10816
• 发表时间: 2020
• 作者: Spence S

Quantum bath suppression in a superconducting circuit by immersion cooling.

• DOI: 10.1038/s41467-023-39249-z
• 发表时间: 2023-06-14
• 期刊: NATURE COMMUNICATIONS
• 影响因子: 16.6
• 作者: Lucas, M.;Danilov, A. V.;Levitin, L. V.;Jayaraman, A.;Casey, A. J.;Faoro, L.;Tzalenchuk, A. Ya.;Kubatkin, S. E.;Saunders, J.;de Graaf, S. E.
• 通讯作者: de Graaf, S. E.

Topological Phase Transitions and New Developments

• DOI: 10.1142/11016
• 发表时间: 2018-08
• 作者: L. Brink;M. Gunn;Jorge V José;J. Kosterlitz;K. K. Phua-K.

High-Performance Cryogen-Free Platform for Microkelvin-Range Refrigeration

用于微开尔文范围制冷的高性能无制冷剂平台

• DOI: 10.1103/physrevapplied.18.l041002
• 发表时间: 2022
• 期刊: Physical Review Applied
• 影响因子: 4.6
• 作者: Nyéki J

Comment on "Stabilized Pair Density Wave via Nanoscale Confinement of Superfluid ^{3}He".

评论“通过超流体 ^{3}He 的纳米级约束稳定对密度波”。

• DOI: 10.1103/physrevlett.125.059601
• 发表时间: 2020
• 期刊: Physical review letters
• 影响因子: 8.6
• 作者: Levitin LV