QII-TAQS: Characterizing and Utilizing 2D van der Wals Materials with Superconducting Qubits

量子信息技术有望给传感、通信和计算带来革命性的变化。实现这一承诺需要创造“量子就绪”材料和制造工艺的新方法。该项目的研究部分引入了一种名为“范德华异质结构”的新型材料，用于制造应用于量子计算的高质量设备。范德华异质结构是一种分层的二维（平面）材料，根据其设计，它们可能具有广泛的特性，比如像铜一样是普通金属，像铝一样是超导体，或者像氧化铝一样是绝缘体。这些材料的优点是它们是结晶的，因此几乎没有（如果有的话）缺陷。这些异质结构的原子尖锐界面也为构建新型电子器件提供了材料平台。缺陷限制了当今量子器件的效用，本研究旨在通过利用它们的结晶度来提高量子器件的性能。这项研究包括范德华异质结构的电学和光学特性的表征，以及它们用于制造和测试一系列量子信息处理有用的量子器件的用途。该项目还有助于培训新一代“量子工程师”，他们将把这项工作转化为工业环境。研究人员致力于指导和培训本科生、研究生和博士后——下一代科学和工程领域的领导者——以及向那些已经在职的人员和其他公众成员伸出援手。本项目研究范德华异质结构（vdW）的表征及其在量子信息技术中的应用。范德华异质结构是一类层状、晶体状、二维（2D）量子材料，包括半金属、绝缘体、半导体、铁磁体、超导体和拓扑绝缘体。虽然vdW材料已经通过直流输运进行了广泛的研究，但很少有实验探测它们在与量子技术应用相关的微波和光学条件下的量子特性。在这项工作中，研究小组使用相干光学技术跨越微波、太赫兹和光学频率，包括直接激发和使用超导谐振器的电路量子电动力学来介导快速、超灵敏的泵浦探针实验和检测，研究二维vdW材料。该团队在vdW材料、高质量因数超导谐振器、高相干超导量子位及其与vdW异质结构的集成方面汇集了互补的专业知识。这些设备的制造利用了内部开发的独特的，最先进的密封设备铸造厂，以及最先进的超导谐振器和量子位制造。测量是在毫开尔文温度下进行的无低温稀释冰箱与微波和光学访问。该研究的目标是变革性的量子信息应用，包括高相干量子比特、小尺寸微波元件和量子自旋模型的研究。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。

Quantum information technologies hold the promise to revolutionize sensing, communication, and computing. Realizing this promise requires new approaches for creating "quantum-ready" materials and manufacturing processes. The research part of this project introduces a new class of materials called "van der Waals heterostructures" to the manufacturing of high-quality devices for application to quantum computation. Van der Waals heterostructures are a family of layered, two-dimensional (flat) materials that - depending on their design - may assume a wide range of properties, such as being a normal metal like copper, a superconductor like aluminum, or an insulator like aluminum oxide. The advantage of these materials is that they are crystalline and, therefore, have few (if any) defects. The atomically sharp interfaces of these heterostructures also provide a materials platform to build novel electronic devices. Defects limit the utility of today's quantum devices, and this research aims to improve quantum device performance by leveraging their crystallinity. The research includes characterization of the electrical and optical properties of van der Waals heterostructures, as well as their use to manufacture and test a range of quantum devices useful for quantum information processing. The project also contributes to the training of a new generation of "quantum engineers" who will translate this work into industrial settings. The investigators are committed to the mentoring and training of undergraduates, graduate students, and postdoctoral associates - the next generation of science and engineering leaders - as well as outreach to those already in the workforce and other members of the public. This project addresses the characterization of van der Waals (vdW) heterostructures - a family of layered, crystalline, two-dimensional (2D) quantum materials including semi-metals, insulators, semiconductors, ferromagnets, superconductors, and topological insulators - and their application to quantum information technologies. While vdW materials have been extensively studied via DC transport, few experiments have probed their quantum properties in the microwave and optical regimes relevant for quantum technology applications. In this work, the research team investigates 2D vdW materials using coherent optical techniques spanning microwaves, terahertz, and optical frequencies, including direct excitation and the use of circuit quantum electrodynamics with superconducting resonators to mediate fast, ultra-sensitive pump-probe experiments and detection. The team aggregates complementary expertise in vdW materials, high-quality-factor superconducting resonators, high coherence superconducting qubits, and their integration with vdW heterostructures. Fabrication of these devices leverages a unique, state-of-the-art hermetic device foundry developed in-house, as well as state of-the-art superconducting resonator and qubit fabrication. Measurements are performed at millikelvin temperature in cryogen-free dilution refrigerators with microwave and optical access. The research targets transformative quantum information applications, including high-coherence qubits, small-form-factor microwave components, and the study of quantum spin models.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.