EAGER: Enabling Quantum Leap: Towards Room Temperature Quantum Logic with Topological Exciton Condensates

EAGER：实现量子飞跃：利用拓扑激子凝聚体实现室温量子逻辑

• 批准号: 1838532
• 负责人: Dong Yu
• 金额: $ 29.96万
• 依托单位: University of California-Davis
• 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: 2018-07-15 至 2021-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1838532&HistoricalAwards=false
• 关键词: EAGER; Enabling; Quantum; Leap; Towards

Nontechnical Description: Quantum computers promise the next great technology leap. At the heart of a quantum computer are material implementations of quantum bits - qubits - which in the present form are highly sensitive to the environment and are typically only achieved at very low temperatures. This project aims to discover a new type of material that may enable room-temperature quantum computing. The new method is based on electrons and their associated vacancies, also known as holes, in a solid material. When an electron lingers close to a hole, the electrical attraction between the pair leads to the formation of a quantum particle known as an exciton. This project explores the utilization of excitons as qubits for enabling quantum logic devices. Recent studies suggest that excitons may be formed above room temperature in a new type of material known as a topological insulator. The principal investigators use a variety of experimental techniques to understand the nature of excitons in topological insulators, and improve the critical temperature for achieving them, so that they may be sustained at room temperature. This project educates and trains undergraduate and graduate students in the important and rapidly advancing research area of quantum computation, and offers outreach activities targeting K-12 students from underrepresented minority groups.Technical Description: Topological exciton condensation is a fundamentally new concept which may open an unexplored and exciting research area. Our recent experimental studies of three-dimensional topological insulators have revealed unusual non-local photocurrent at liquid nitrogen temperature, indicating a superfluid-like topological exciton condensate. This project builds on these exciting preliminary results and aims to obtain fundamental understanding of topological exciton condensates. Experiments to unambiguously distinguish the free Fermion and exciton mechanisms by conducting electric field dependent photocurrent mapping are performed. Spatially resolved angle-resolved photoemission spectroscopy (micro-ARPES) supports this effort by characterizing the occupied single-particle spectrum of materials platforms where signatures of an excitonic condensate are observed. Ultrafast spectroscopy is carried out to measure exciton lifetime and velocity. The exciton induced spin polarization is explored using Kerr rotation. An even higher onset temperature for exciton condensation is achieved in thinner and more intrinsic samples and other low dimensional topological materials beyond Bi2Se3. The topological exciton condensate, a high-temperature macroscopic quantum state with long coherence lengths and unique spin texture, has a truly promising potential to be implemented in room-temperature quantum computers.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：量子计算机预示着下一个伟大的技术飞跃。量子计算机的核心是量子比特的材料实现——量子位——以目前的形式对环境高度敏感，通常只能在非常低的温度下实现。该项目旨在发现一种可以实现室温量子计算的新型材料。这种新方法是基于固体材料中的电子及其相关的空位（也称为空穴）。当一个电子在空穴附近徘徊时，电子对之间的电吸引力导致一种称为激子的量子粒子的形成。本项目探索利用激子作为量子比特来实现量子逻辑器件。最近的研究表明，激子可以在室温以上的一种被称为拓扑绝缘体的新型材料中形成。主要研究人员使用各种实验技术来了解拓扑绝缘体中激子的性质，并提高实现它们的临界温度，以便它们可以在室温下持续存在。该项目在量子计算这一重要且快速发展的研究领域对本科生和研究生进行教育和培训，并为来自代表性不足的少数群体的K-12学生提供外展活动。技术描述：拓扑激子凝聚是一个全新的概念，它可能打开一个未开发的和令人兴奋的研究领域。我们最近对三维拓扑绝缘体的实验研究揭示了液氮温度下不寻常的非局部光电流，表明了超流体样拓扑激子凝聚。该项目建立在这些令人兴奋的初步结果的基础上，旨在获得对拓扑激子凝聚体的基本理解。通过进行电场相关的光电流映射来明确区分自由费米子和激子机制的实验。空间分辨角分辨光谱学（micro-ARPES）通过表征材料平台的占据单粒子光谱来支持这一努力，其中观察到激子凝聚物的特征。采用超快光谱法测量激子的寿命和速度。利用克尔旋转研究了激子诱导的自旋极化。除了Bi2Se3之外，在更薄、更本征的样品和其他低维拓扑材料中，激子凝结的起始温度更高。拓扑激子凝聚态是一种具有长相干长度和独特自旋织构的高温宏观量子态，在室温量子计算机中具有很好的应用前景。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。

项目成果

Nonlocal Chemical Potential Modulation in Topological Insulators Enabled by Highly Mobile Trapped Charges

• DOI: 10.1021/acsaelm.0c00701
• 发表时间: 2020-10
• 作者: Yasen Hou;Ruijuan Xiao;Senlei Li;Lang Wang;Dong Yu

Nanosecond dynamics in intrinsic topological insulator Bi2−xSbxSe3 revealed by time-resolved optical reflectivity

• DOI: 10.1103/physrevb.103.l020301
• 发表时间: 2021-01
• 期刊: Physical Review B
• 影响因子: 3.7
• 作者: Adam L. Gross;Yasen Hou;A. Rossi;Dong Yu;I. Vishik

Millimetre-long transport of photogenerated carriers in topological insulators

• DOI: 10.1038/s41467-019-13711-3
• 发表时间: 2019-12
• 期刊: Nature Communications
• 影响因子: 16.6
• 作者: Yasen Hou;Rui Wang;Ruijuan Xiao;L. McClintock;Henry Clark Travaglini;John Paulus Francia;H. Fetsch;O. Erten;S. Savrasov;Baigeng Wang;A. Rossi;I. Vishik;E. Rotenberg;Dong Yu

Superconducting quantum interference devices made of Sb-doped Bi2Se3 topological insulator nanoribbons

• DOI: 10.1016/j.cap.2020.02.020
• 发表时间: 2020-02
• 期刊: Current Applied Physics
• 影响因子: 2.4
• 作者: N. Kim;Hong-Seok Kim;Yasen Hou;Dong Yu;Yong-Joo Doh

Modeling of the photocurrent induced by inverse spin Hall effect under local circularly polarized photoexcitation

• DOI: 10.1103/physrevb.104.205413
• 发表时间: 2021-11
• 期刊: Physical Review B
• 影响因子: 3.7
• 作者: Kuen Wai Tang;B. Wang;H. C. Travaglini;D. Yu