Collaborative Research: One-Dimensional Correlated and Topological Electronic States in Ultra-Clean Carbon Nanotubes

合作研究：超洁净碳纳米管中的一维关联和拓扑电子态

• 批准号: 2005182
• 负责人: Vikram Deshpande
• 金额: $ 29.61万
• 依托单位: University of Utah
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2020
• 资助国家: 美国
• 起止时间: 2020-07-01 至 2024-06-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2005182&HistoricalAwards=false
• 关键词: Collaborative; Research; Dimensional; Correlated; Topological

Non-Technical: By integrating metals and semiconductors into circuits, humans have learned to control the flow of electrons to process information. Despite enormous successes in this field, there are still unsolved challenges. Existing methods to control electron flow produce imprecise levels of electrical current, and often lead to energy wasted as heat. In this project, the team explores a new way of controlling electric current using a novel method for pumping electrons. The pump is built from a single carbon nanotube that is integrated with a microscopic pattern of wires that controls a time-varying electric field. The pump is predicted to carry an electrical current without dissipation of energy. It is also predicted to be useful as a metrological standard for generating a precise current from a frequency source. Additionally, the system unravels new knowledge about the behavior of interacting electrons which is fundamentally different in such reduced-dimensional systems. The project trains students including under-represented minorities and strengthens the pipeline that feeds the science and engineering workforce. Outreach activities for high-school students from under-represented minorities include an annual science summer camp. Technical: One dimensional (1D) electronic systems are naturally correlated, in contrast to the Fermi liquids that usually form in higher (two and three) dimensions. While topological order has been studied intensely in 2D and 3D, it has received relatively little attention in 1D where the combination of topology and correlations leads to fascinating possibilities. In the early 80s, Thouless predicted that the same topological invariant as in the quantum Hall effect arises in 1D systems, when the magnetic field is replaced by a time-varying periodic potential. This system, known as an adiabatic charge pump or Thouless pump, has not been realized cleanly in condensed matter, due to problems of single-electron charging and sample disorder. The research team’s preliminary results demonstrate the suitability of their long, suspended, ultra-clean carbon nanotubes (CNTs) for realizing the Thouless pump, and related exotic phenomena. Electrons in a long, ultra-clean CNT form either a Wigner crystal, Luttinger liquid, or a correlated insulator state. Upon application of the periodic potential, the system may then evolve into an integer Thouless pump, a fractional Thouless pump, an artificial Mott insulator or other exotic states. This project focuses on the rich physics that can be found in, and between, these exotic states. To access and control the various phenomena, the team will tune (i) the electron density in the CNT, (ii) the wavelength of the external potential, and (iii) the Coulomb interaction strength (a function of CNT band gap). The specific aims of the project are: 1. Map the parameter space of 1D correlated states in the CNT system without an external periodic potential. 2. Introduce topological order by generating an external periodic potential with surface acoustic waves and a precision flip-chip geometry. 3. Study the interplay of correlations and topological order in 1D.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.

非技术性：通过将金属和半导体集成到电路中，人类已经学会了控制电子流来处理信息。尽管在这一领域取得了巨大成功，但仍存在尚未解决的挑战。控制电子流的现有方法产生不精确的电流水平，并且通常导致能量作为热量浪费。在这个项目中，该团队探索了一种新的方法来控制电流，使用一种新的方法来泵送电子。该泵由单个碳纳米管制成，该碳纳米管与控制时变电场的微观电线图案集成在一起。该泵被预测为携带电流而不耗散能量。它也被预测是有用的，作为一个标准的频率源产生一个精确的电流。此外，该系统揭示了关于相互作用电子行为的新知识，这在这种降维系统中是根本不同的。该项目培训学生，包括代表性不足的少数民族，并加强了为科学和工程劳动力提供支持的渠道。为代表性不足的少数族裔高中生开展的外联活动包括每年的科学夏令营。技术支持：一维（1D）电子系统是自然相关的，而费米液体通常形成在更高的（二维和三维）维度。虽然拓扑序在2D和3D中得到了深入的研究，但在1D中却很少受到关注，因为拓扑和相关性的结合带来了迷人的可能性。在80年代早期，李泽钜预言，当磁场被时变周期势所取代时，1D系统中会出现与量子霍尔效应相同的拓扑不变量。这个系统，被称为绝热电荷泵或无电荷泵，由于单电子充电和样品无序的问题，还没有在凝聚态物质中干净地实现。研究小组的初步结果证明了他们的长，悬浮，超清洁碳纳米管（CNT）用于实现无污染泵和相关奇异现象的适用性。在一个长的，超干净的碳纳米管的电子形式要么维格纳晶体，Luttinger液体，或相关的绝缘体状态。在施加周期性势时，系统然后可以演变成整数无源泵浦、分数无源泵浦、人工莫特绝缘体或其他奇异状态。这个项目的重点是丰富的物理，可以发现，和之间，这些异国情调的状态。为了访问和控制各种现象，该团队将调整（i）CNT中的电子密度，（ii）外部电势的波长，以及（iii）库仑相互作用强度（CNT带隙的函数）。该项目的具体目标是：1。在没有外加周期势的情况下，绘制了碳纳米管系统中一维关联态的参数空间。2.通过表面声波和精确的倒装芯片几何形状产生外部周期势，引入拓扑序。3.该奖项反映了NSF的法定使命，并已被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

项目成果

Quantum Interferences in Ultraclean Carbon Nanotubes

• DOI: 10.1103/physrevlett.126.216802
• 发表时间: 2021-05-26
• 期刊: PHYSICAL REVIEW LETTERS
• 影响因子: 8.6
• 作者: Lotfizadeh, Neda;Senger, Mitchell J.;Deshpande, Vikram V.
• 通讯作者: Deshpande, Vikram V.