Induced Topological Superconductivity in Two Dimensional Systems

二维系统中的诱导拓扑超导

• 批准号: 1708688
• 负责人: Amir Yacoby
• 金额: $ 68万
• 依托单位: Harvard University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-08-01 至 2022-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1708688&HistoricalAwards=false
• 关键词: Induced; Topological; Superconductivity; Two; Dimensional

Non-Technical Abstract:Nearly a hundred years after its discovery, superconductivity remains one of the most intriguing phases of matter. In 1957 Bardeen, Cooper and Schrieffer (BCS) presented their theory of superconductivity describing this state in terms of pairs of electrons arranged in a spatially isotropic wave function with no net momentum and a spin singlet configuration. Immediately thereafter, a search began to find materials with unconventional superconductivity where pairing deviates from conventional BCS theory. One particular class of unconventional superconductors involves pairs arranged in triplet rather than singlet configurations. Such superconductors may enable dissipationless transport of spin and may also give rise to elementary excitations that do not obey the conventional Fermi or Bose statistics but rather have non-Abelian statistics where the exchange of two particles transforms the state of the system into a new quantum mechanical state. This project explores unconventional superconductivity that arises due to the proximity effect between a conventional superconductor and a semiconductor with strong spin-orbit interaction. The research team looks to identify signatures of non-Abelian excitations and explore their properties using a variety of transport techniques. The research addresses three of the broader impact criteria set forth by the NSF: Benefits to Society through the exploration of dissipationless storage and transfer of information; Promoting teaching, training and education through the development of undergraduate courses; and broader participation of underrepresented groups through the active hiring of promising female scientists into the program.Technical Abstract:A research project is proposed to investigate topological superconductivity in two dimensional systems. The work follows recent theoretical work suggesting three distinct experimental platforms where topological superconductivity in two dimensions emerges. The first consists of topological HgCdTe quantum wells. The robust helical nature of the quantum spin Hall Effect seen in this system and its predicted dependence on an external magnetic field is particularly promising for exploring the underlying Andreev bound states spectrum as direct means for observing signatures of Majorana modes. The second platform consists of two dimensional Josephson junctions where the normal medium consists of non-topological 2D semiconductors with strong spin-orbit interaction (such as InAs quantum wells and narrow wells of HgCdTe). Such a platform was recently proposed as a promising controllable system where topological superconductivity can be tuned using an external in-plane magnetic field and the phase difference across the two superconducting contacts. The third approach consists of using quantum Hall edges in HgTe and quantum Anomalous Hall edges in vanadium doped (Bi,Sb)2Te3 for exploring topological superconductivity in chiral edges. The strong spin orbit coupling in HgTe quantum wells and the absence of an external magnetic field required for exploring the anomalous quantum Hall effect opens up rich and unexplored possibilities for exploring chiral Majorana modes. The experimental methods proposed include tunneling spectroscopy of Andreev bound states and noise magnetometry using nitrogen vacancy centers in diamond for exploring the fractional current phase relations in these systems.

非技术摘要：超导性在被发现近一百年后，仍然是物质最有趣的阶段之一。1957年，Barclay、库珀和Schrieffer（BCS）提出了他们的超导理论，描述了这种状态，用电子对排列在空间各向同性波函数中，没有净动量和自旋单态配置。紧接着，研究人员开始寻找具有非常规超导性的材料，其中配对偏离了传统的BCS理论。有一类特殊的非传统超导体是以三重态而非单重态排列的对。这样的超导体可以实现自旋的无耗散传输，并且还可以产生不遵守传统费米或玻色统计而是具有非阿贝尔统计的元激发，其中两个粒子的交换将系统的状态转换为新的量子力学状态。该项目探讨了由于传统超导体和具有强自旋轨道相互作用的半导体之间的邻近效应而产生的非常规超导性。研究小组希望识别非阿贝尔激发的特征，并使用各种传输技术探索它们的特性。该研究解决了NSF提出的三个更广泛的影响标准：通过探索无耗散存储和信息传输对社会的好处;通过开发本科课程促进教学，培训和教育;通过积极雇用有前途的女性科学家参与该计划，使代表性不足的群体更广泛地参与。技术摘要：提出了一个研究二维系统中拓扑超导性的计划。这项工作遵循最近的理论工作，提出了三个不同的实验平台，其中出现了二维拓扑超导性。第一种是拓扑HgCdTe量子威尔斯阱。在这个系统中看到的量子自旋霍尔效应的强大的螺旋性质及其对外部磁场的预测依赖性是特别有前途的探索潜在的Andreev束缚态谱作为直接手段观察签名的马约拉纳模式。第二个平台由二维约瑟夫森结组成，其中正常介质由具有强自旋轨道相互作用的非拓扑二维半导体（例如InAs量子威尔斯和HgCdTe窄威尔斯阱）组成。这样的平台最近被提出作为一个有前途的可控系统，其中拓扑超导性可以使用外部面内磁场和两个超导接触之间的相位差进行调谐。第三种方法是利用HgTe中的量子Hall边和钒掺杂（Bi，Sb）2 Te 3中的量子反常Hall边来研究手征边的拓扑超导性。碲化汞量子威尔斯阱中的强自旋轨道耦合和探索反常量子霍尔效应所需的外部磁场的存在为探索手性马约拉纳模式开辟了丰富和未探索的可能性。所提出的实验方法包括Andreev束缚态的隧道谱和利用金刚石中的氮空位中心的噪声磁强计来探索这些系统中的分数电流相位关系。

项目成果

Topological superconductivity in a phase-controlled Josephson junction

• DOI: 10.1038/s41586-019-1148-9
• 发表时间: 2019-05-02
• 期刊: NATURE
• 影响因子: 64.8
• 作者: Ren, Hechen;Pientka, Falko;Yacoby, Amir
• 通讯作者: Yacoby, Amir

Signatures of long-range-correlated disorder in the magnetotransport of ultrathin topological insulators

• DOI: 10.1103/physrevb.98.214203
• 发表时间: 2018-12-19
• 期刊: PHYSICAL REVIEW B
• 影响因子: 3.7
• 作者: Nandi, D.;Skinner, B.;Yacoby, A.
• 通讯作者: Yacoby, A.

Spectroscopic signatures of time-reversal symmetry breaking superconductivity

• DOI: 10.1038/s42005-022-00819-0
• 发表时间: 2022-02
• 期刊: Communications Physics
• 影响因子: 5.5
• 作者: N. R. Poniatowski;J. Curtis;A. Yacoby;P. Narang

Topological Superconductivity in a Planar Josephson Junction

• DOI: 10.1103/physrevx.7.021032
• 发表时间: 2017-05-30
• 期刊: PHYSICAL REVIEW X
• 影响因子: 12.5
• 作者: Pientka, Falko;Keselman, Anna;Halperin, Bertrand I.
• 通讯作者: Halperin, Bertrand I.

Proximity-induced collective modes in an unconventional superconductor heterostructure

• DOI: 10.1103/physrevb.106.064508
• 发表时间: 2022-01
• 期刊: Physical Review B
• 影响因子: 3.7
• 作者: J. Curtis;N. R. Poniatowski;A. Yacoby;P. Narang