RAISE-TAQS: Topologically-Engineered Graphene Nanoribbon-based Quantum Systems

RAISE-TAQS：拓扑工程石墨烯纳米带量子系统

• 批准号: 1839098
• 负责人: Michael Crommie
• 金额: $ 100万
• 依托单位: University of California-Berkeley
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-09-15 至 2022-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1839098&HistoricalAwards=false
• 关键词: RAISE; TAQS; Topologically; Engineered; Graphene

Non-technical description: The goal of this project is to make operational quantum bits (qubits) from graphene nanoribbons (GNRs). Qubits are the building blocks of devices that manipulate quantum information for purposes such as cryptography, simulations, and a variety of other computational tasks. Due to the extraordinary properties of quantum mechanics, quantum information devices (such as quantum computers) are expected to perform calculations significantly beyond what conventional classical computers can ever hope to do. GNRs (which are very narrow strips of graphene) are an exciting new platform for creating qubits because they have excellent electronic, thermal, and mechanical properties, and they can be efficiently fabricated from 'the bottom-up' (i.e., molecule-by-molecule) with atomic precision. The main idea of this project is to incorporate qubits into GNRs by causing individual electrons to be trapped at predetermined locations along the backbone of chemically-engineered GNRs. Because GNRs are molecule-scale structures, qubits arranged in this way could potentially yield quantum devices having reduced size, increased density, and structural flexibility that is unmatched by any other qubit platform. A major focus of this project is to synthesize such GNR-based qubits and to characterize them at the atomic-scale using techniques that include scanning tunneling microscopy and atomic force microscopy. Based on the results of these measurements, suitable GNR qubit candidates are chosen for incorporation into devices designed to measure their quantum properties. The viability of GNR-based qubits as a new quantum information platform is evaluated through this procedure. The broader impacts of this project lie in its strong education and outreach components and the fact that it provides high-level scientific training to graduate students, undergraduates, and high school students, preparing them for careers in science, technology, engineering, and math (STEM) fields. Quantum scientists are trained in how to combine chemistry, material science, and engineering in new interdisciplinary ways. The California community college system has additionally been targeted by this project as a useful conduit for recruiting new STEM majors who better represent the demographics of our nation. This project incorporates a realistic plan to partner with a Bay Area community college in order to develop a new quantum information curriculum that is accessible to community college students, that allow them to transfer their credits to the University of California system, and create new opportunities for them to become involved in cutting-edge research. Technical description: The main goal of this project is to evaluate a new type of graphene nanoribbon (GNR) system for suitability as a quantum information device platform. Qubit functionality in GNRs arises from a recent discovery made by the investigators of this research team that GNRs can host topologically-protected interface states that each contain a single electron spin. These topological interfaces can be engineered at the molecular level and provide a new method for controlling electronic and spin behavior in GNR-based nanostructures. A double-interface GNR geometry has been chosen for this project that places two topological interface states in close proximity, thus allowing the resulting singlet/triplet spin configurations to provide qubit functionality (analogous to the singlet/triplet qubit subspace of Si and GaAs double-quantum-dots). Due to graphene's highly desirable electronic, thermal, and mechanical properties, GNR qubits are expected to have long decoherence times, to function at very high packing density, and to be very device-compatible. Established bottom-up synthesis methods additionally allow atomically-precise GNR structures to be fabricated via highly efficient self-assembly processes. This project is performed by an interdisciplinary research team comprised of three investigators with strengths in chemistry, material science, and electrical engineering. F. Fisher heads the project's chemistry-based efforts to design precursor molecules that self-assemble into topological GNR qubits. M. F. Crommie heads material science-based efforts to characterize the local electronic and spin properties of resulting qubit structures using scanned probe microscopy. J. Bokor heads efforts to incorporate suitable GNR qubit systems into quantum devices for functional evaluation. Fundamental questions addressed by this project include whether topological GNR interface states can be coupled into multi-spin qubit centers, initialized into well-defined quantum states, and efficiently read out. The competition between interface state hybridization effects and on-site Coulomb repulsion is explored through atomically-precise manipulation of the GNR chemical structure, thus presenting new physical regimes for quantum spin engineering that are relevant for quantum information applications. New methods of coupling GNR qubits are planned, including ideas for inducing entanglement between qubits and for addressing individual GNR qubits via electronic nanodevices, assessing the viability of GNRs as a quantum information platform.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.

非技术描述：该项目的目标是从石墨烯纳米带（GNR）中制造可操作的量子比特（qubit）。量子比特是操纵量子信息的设备的构建块，用于加密、模拟和各种其他计算任务等目的。由于量子力学的非凡性质，量子信息设备（如量子计算机）预计将执行远远超出传统经典计算机所能做的计算。GNR（是非常窄的石墨烯条）是一种令人兴奋的用于创建量子位的新平台，因为它们具有优异的电子，热学和机械特性，并且它们可以从“自下而上”（即，以原子级精度逐分子地进行）。该项目的主要思想是通过使单个电子被捕获在沿着化学工程GNR骨架的预定位置沿着，将量子比特纳入GNR。由于GNR是分子级结构，以这种方式排列的量子位可能会产生具有减小的尺寸、增加的密度和结构灵活性的量子器件，这是任何其他量子位平台无法比拟的。该项目的一个主要重点是合成这种基于GNR的量子比特，并使用扫描隧道显微镜和原子力显微镜等技术在原子尺度上对其进行表征。基于这些测量的结果，选择合适的GNR量子比特候选者，以并入设计用于测量其量子特性的设备中。基于GNR的量子比特作为一种新的量子信息平台的可行性进行了评估，通过这个过程。该项目更广泛的影响在于其强大的教育和推广组件，以及它为研究生，本科生和高中生提供高水平的科学培训，为他们在科学，技术，工程和数学（STEM）领域的职业生涯做好准备。量子科学家接受如何以新的跨学科方式将化学、材料科学和工程结合起来的联合收割机培训。加州社区学院系统也被这个项目作为招募新的STEM专业的有用渠道，这些专业更好地代表了我们国家的人口统计数据。该项目结合了一个现实的计划，与湾区社区学院合作，以开发一个新的量子信息课程，该课程可供社区学院学生使用，使他们能够将学分转移到加州大学系统，并为他们创造新的机会参与尖端研究。技术说明：该项目的主要目标是评估一种新型石墨烯纳米颗粒（GNR）系统作为量子信息设备平台的适用性。GNR中的量子比特功能源于该研究小组的研究人员最近发现的GNR可以托管拓扑保护的界面态，每个界面态都包含一个电子自旋。这些拓扑界面可以在分子水平上进行工程设计，并为控制GNR基纳米结构中的电子和自旋行为提供了一种新方法。该项目选择了双界面GNR几何结构，将两个拓扑界面态紧密靠近，从而允许产生的单线态/三线态自旋配置提供量子比特功能（类似于Si和GaAs双量子点的单线态/三线态量子比特子空间）。由于石墨烯具有非常理想的电子，热和机械特性，GNR量子比特预计具有较长的退相干时间，以非常高的封装密度运行，并且非常兼容设备。已建立的自下而上的合成方法还允许通过高效的自组装工艺制造原子级精确的GNR结构。该项目由一个跨学科的研究团队进行，该团队由三名在化学，材料科学和电气工程方面具有优势的研究人员组成。F.费舍尔领导该项目的化学基础的努力，设计前体分子，自组装成拓扑GNR量子比特。M. F.克罗米领导了基于材料科学的工作，使用扫描探针显微镜来表征所得量子位结构的局部电子和自旋性质。J. Bokor领导了将合适的GNR量子比特系统纳入量子设备进行功能评估的努力。该项目解决的基本问题包括拓扑GNR界面态是否可以耦合到多自旋量子位中心，初始化为定义良好的量子态，并有效地读出。通过对GNR化学结构的原子级精确操纵，探索了界面态杂化效应和原位库仑排斥之间的竞争，从而为量子信息应用相关的量子自旋工程提出了新的物理机制。计划耦合GNR量子位的新方法，包括诱导量子位之间的纠缠和通过电子纳米器件寻址单个GNR量子位的想法，评估GNR作为量子信息平台的可行性。该奖项反映了NSF的法定使命，并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，被认为值得支持。

项目成果

Bottom‐Up Synthesized Nanoporous Graphene Transistors

• DOI: 10.1002/adfm.202103798
• 发表时间: 2021-08
• 期刊: Advanced Functional Materials
• 影响因子: 19
• 作者: Zafer Mutlu;P. Jacobse;Ryan D McCurdy;J. Llinas;Yuxuan Lin;Gregory Veber;F. Fischer;M. Crommie-

Ultralow contact resistance between semimetal and monolayer semiconductors

• DOI: 10.1038/s41586-021-03472-9
• 发表时间: 2021-05-13
• 期刊: NATURE
• 影响因子: 64.8
• 作者: Shen, Pin-Chun;Su, Cong;Kong, Jing
• 通讯作者: Kong, Jing

Bottom-up Assembly of Nanoporous Graphene with Emergent Electronic States

• DOI: 10.1021/jacs.0c05235
• 发表时间: 2020-08-05
• 期刊: JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
• 影响因子: 15
• 作者: Jacobse, Peter H.;McCurdy, Ryan D.;Crommie, Michael F.
• 通讯作者: Crommie, Michael F.

Inducing metallicity in graphene nanoribbons via zero-mode superlattices

• DOI: 10.1126/science.aay3588
• 发表时间: 2020-09-25
• 期刊: SCIENCE
• 影响因子: 56.9
• 作者: Rizzo, Daniel J.;Veber, Gregory;Crommie, Michael F.
• 通讯作者: Crommie, Michael F.

Transfer-Free Synthesis of Atomically Precise Graphene Nanoribbons on Insulating Substrates

绝缘基底上原子级精确石墨烯纳米带的无转移合成

• DOI: 10.1021/acsnano.0c07591
• 发表时间: 2021
• 期刊: ACS Nano
• 影响因子: 17.1
• 作者: Mutlu, Zafer;Llinas, Juan Pablo;Jacobse, Peter H.;Piskun, Ilya;Blackwell, Raymond;Crommie, Michael F.;Fischer, Felix R.;Bokor, Jeffrey
• 通讯作者: Bokor, Jeffrey