NSF/DMR-BSF: Quantum Transport in a Helical One-Dimensional System

非技术摘要：硅晶体管的发明和学术界和工业界几十年的研究发展，导致了当前以计算机和互联网为特征的信息快速处理和传播时代。硅晶体管正迅速接近其性能极限。要超越传统的硅技术，需要完全不同的范式，这些范式本质上是量子的，并且在尚未发现的新材料和设备概念上运行。量子线可以在不耗散能量的情况下传输电流，在不失去相干性的情况下传输携带信息的量子态，是下一代量子计算机和量子网络的重要组成部分。在之前的研究中，PI的实验室发现了一种具有上述潜力的新型量子线。该项目的目标是进一步了解导线的基本特性，并通过构建纳米级设备和在此类系统中进行测量来开发其技术潜力。在这项研究中获得的知识预计将对量子电子学的发展产生重大影响。这些研究活动旨在教育下一代量子技术劳动力。技术摘要：PI的实验室最近在双层石墨烯中开创了一种新的一维螺旋系统，称为扭结态，其中电子的谷自由度被锁定在其传播方向上。向相反方向运动的电子携带相反的谷指数。谷动量锁定量子线显示出优异的弹道输运特性，并支持拓扑谷阀、波导和可调谐电子束分离器的操作，PI实验室已经证明了这一点。该项目旨在进一步发展能力，以操纵和探测超越电导测量的扭结状态的相互作用。研究活动旨在构建一个量子点接触，并利用该平台的通用可调性来系统地研究量子点接触中扭结态的受控耦合，特别是相互作用的一维系统的特征。马赫-曾德尔干涉仪的构造使得研究扭结态的相相干输运成为可能。研究工作还包括通过超导体-扭结-超导体结将扭结态耦合到高临界场超导体上，并了解扭结态携带的超电流分布。这些实验为研究超导体扭结杂化结构中的涌现现象奠定了基础。在对测量结果的解释和预测中，理论的努力有助于实验。在这个项目中获得的实验和理论知识从根本上丰富了对拓扑、超导和一维物理的理解。研究活动为各级学生提供了在STEM领域从事职业所需的技能，夏令营活动促进了高中生的科学领导能力。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 abstract: The invention of the silicon transistor and decades of research development by academia and industry led to the current era of rapid information processing and propagation characterized by computers and the internet. The silicon transistor is rapidly approaching its limit of performance. To go beyond the conventional silicon technology requires drastically different paradigms that are fundamentally quantum in nature and operate on new materials and device concepts that are yet to be discovered. Quantum wires that can carry current without dissipating energy and transport information-carrying quantum states without losing coherence are an important building block of the next-generation quantum computers and quantum networks. In prior research, the PI's lab discovered a new type of quantum wire that has the above potential. The objectives of this project are to further understand the fundamental properties of the wires and develop its technological potential by constructing nanoscale devices and performing measurements in such systems. Knowledge gained in this research is expected to have significant impact on the development of quantum electronics. The research activities aim to educate the next-generation workforce of quantum technologies. Technical abstract: The PI's lab recently pioneered a new one-dimensional helical system in bilayer graphene known as the kink states, where the valley degrees of freedom of an electron is locked to its direction of propagation. Electrons moving in opposite directions carry opposite valley indices. The valley-momentum locked quantum wires display excellent ballistic transport properties and support the operations of a topological valley valve, a waveguide and a tunable electron beam splitter, which the PI's lab demonstrated. This project seeks to further develop capabilities to manipulate and probe interactions of the kink states beyond conductance measurements. The research activities aim to construct a quantum point contact and utilize the versatile tunability of the platform to systematically examine the controlled coupling of the kink states at the quantum point contact, in particular signatures of interacting one-dimensional systems. The construction of a Mach-Zehnder interferometer enables the studies of phase coherence transport of the kink states. Research efforts also include coupling the kink states to a high upper-critical-field superconductor through superconductor-kink-superconductor junctions and understanding the supercurrent distribution carried by the kink states. These experiments lay the foundation of pursuing emergent phenomena in superconductor-kink hybrid structures. Experiments are aided by theoretical efforts in the interpretation and prediction of measurements. Experimental and theoretical knowledge obtained in this project fundamentally enrich the understandings of topology, superconductivity and one-dimensional physics. The research activities equip students of all levels with necessary skills to pursue careers in STEM fields and summer camp activities promote science leadership among high school students.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.