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

非技术描述：量子计算机有望实现下一次伟大的技术飞跃。量子计算机的核心是量子比特的材料实现-量子比特-目前的形式对环境高度敏感，通常只有在非常低的温度下才能实现。该项目旨在发现一种可能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，电子对之间的电引力会导致一种称为激子的量子粒子的形成。这个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，激子可能在一种被称为拓扑绝缘体的新型材料中在室温以上形成。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，并提高实现激子的临界温度，以便在室温下保持激子的存在。该项目在重要和快速发展的量子计算研究领域教育和培训本科生和研究生，并提供针对K-12学生的推广活动，这些学生来自未被充分代表的少数群体。技术描述：拓扑激子凝聚是一个全新的概念，可能会打开一个未知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发现，在液氮温度下出现了反常的非局域光电流，这表明它是一种超流态的拓扑激子凝聚体。这个项目建立在这些令人振奋的初步结果的基础上，旨在获得对拓扑激子凝聚的基本理解。通过进行依赖于电场的光电流映射，实验明确地区分了自由费米子和激子机制。空间分辨角度分辨光电子能谱(Micro-ARPES)通过表征被占据的材料平台的单粒子光谱来支持这一工作，其中观察到激子凝聚体的特征。用超快光谱测量激子寿命和速度。利用克尔旋转研究了激子诱导的自旋极化。在比Bi2Se_3更薄、更本征的样品和其他低维拓扑材料中，激子凝聚的起始温度甚至更高。拓扑激子凝聚态是一种具有长相干长度和独特自旋结构的高温宏观量子态，具有在室温量子计算机中实现的真正有希望的潜力。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

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.