RUI: Theoretical Studies of Qubit-Based Environmental Noise Characterization in Solid State Devices

非技术总结对量子力学状态的操纵为需要量子力学来理解和预测其操作的设备打开了新的可能性。应用包括量子信息处理、通信和传感。利用起源于量子力学的纳米级固态系统的特性受到退相干的阻碍，退相干是通过量子系统与其环境之间的不受控制的相互作用来破坏量子力学状态的特性的过程。近年来，出现了一种解决退相干问题的新范式。研究人员颠覆了这个问题。研究人员没有使用量子计算机中的基本信息单位-量子比特来进行量子计算，而是使用量子比特作为敏感的探测器来提取关于基本噪声机制的有价值的信息。该奖项支持一个理论研究和本科教育计划，旨在通过阐明量子环境下噪声理论中的一些主要开放问题来改进当前表征噪声的方法。这项研究的结果可能会对基于量子力学的技术产生影响，包括量子计算、量子通信和量子计量学。这项研究开发的噪声光谱学技术可能会影响下一代多量子比特设备的设计，这些设备预计将暴露在更复杂的噪声环境中。该奖项支持的项目将在圣克拉拉大学进行，该大学主要是一所本科院校，并将在整个过程中通过独立研究项目为本科生提供教育机会。学生将参与尖端物理研究，培训他们先进的理论方法和高端数值分析。各种理论方法和工作模式将确保学生将追求多条和独立的调查路线，以便在全职暑期内完成自给自足的研究项目。参赛学生将接触到量子计算高度活跃和跨学科研究领域的领先实验和理论成果。技术总结该奖项支持专注于基于量子比特的环境噪声表征的理论研究和本科教育。这项研究旨在阐明噪声检测技术中的一些主要悬而未决的问题，这些技术利用适当选择的动态解耦(DD)脉冲序列下的量子比特读出来有效地扫描噪声功率谱。研究将旨在提高这些DD噪声光谱(DDNS)技术的分辨率和扩展其适用性。用于多光谱重建的DDNS协议将被设计用于检测非高斯噪声的特征。该方法将被用于研究固态量子系统中的电荷涨落，它可以作为一种灵敏的工具来绘制局部涨落的位置和特征。在另一个不同的应用中，非高斯噪声光谱将被用来利用钻石中的氮空位中心来改进核自旋检测。多量子比特DDNS技术将被开发来解决多个噪声源和在强耦合环境中检测量子噪声。这些方法将被应用于相互作用涨落的量子模型的研究，重温自旋-飞子模型。两个横向噪声的问题将在一个一般的框架下进行分析，该框架同时考虑了退相和耗散，适用于一般的量子比特工作点。该理论将应用于常见的量子点单态-三态自旋量子比特同时受到电荷和核噪声困扰的场景。最后，在DDNS之外，将探索其他基于量子比特的环境噪声表征方法，包括基于自旋锁定的连续驱动量子比特光谱和相关投射测量。该奖项支持的计划将在圣克拉拉大学实施，并将在整个过程中通过独立研究项目为本科生提供教育机会。在这个以本科为主的学院，学生将熟悉噪声理论、半导体物理和基础量子力学，并将接触到广泛的分析和数值方法。由于这些主题的科学和技术重要性，学生将受益于研究经验，这将为他们在学术界和工业中的广泛职业生涯做好准备。该奖项反映了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。

NON-TECHNICAL SUMMARYThe manipulation of quantum mechanical states opens new possibilities for devices that require quantum mechanics to understand and predict their operation. Applications include quantum information processing, communication, and sensing. Exploiting characteristics of nanoscale solid-state systems that have a quantum mechanical origin is hampered by decoherence, a process that spoils the properties of quantum mechanical states through the uncontrolled interactions between the quantum system and its environment. In recent years a new paradigm to address the issue of decoherence has emerged. Researchers have turned the problem on its head. Rather than using qubits - the fundamental unit of information in a quantum computer to do quantum computation, researchers are using qubits as sensitive probes to extract valuable information about fundamental noise mechanisms.This award supports a theoretical research and undergraduate education program aimed at improving current methods of characterizing noise by elucidating some of the main open questions in noise theory in the context of quantum environments. The outcomes of this research may have impact on quantum-mechanics-based technologies including quantum computation, quantum communication, and quantum metrology. Noise spectroscopy techniques developed in this research may influence the design of the next generation of multiqubit devices, which are expected to be exposed to more complicated noise environments.The program supported through this award will be carried out at Santa Clara University, a Primarily Undergraduate Institution, and will provide educational opportunities for undergraduate students through independent research projects throughout its duration. Students will participate in cutting-edge physics research that will train them in advanced theoretical methods and high-end numerical analysis. A variety of theoretical methods and work modalities will ensure that students will pursue multiple and independent lines of investigation so that self-contained research projects can be completed within a full-time summer period. Participating students will be exposed to the leading experimental and theoretical endeavors in the highly vibrant and interdisciplinary research field of quantum computing.TECHNICAL SUMMARYThis award supports theoretical research and undergraduate education focused on qubit-based environmental noise characterization. The research is aimed to elucidate some of the main open questions in noise detection techniques that utilize qubit readouts under properly chosen dynamical decoupling (DD) pulse sequences to effectively scan the noise power spectrum. Studies will aim at enhancing the resolution and extending the applicability of these DD noise spectroscopy (DDNS) techniques.DDNS protocols for polyspectra reconstruction will be designed to detect signatures of non-Gaussian noise. The method will be applied to study charge fluctuations in solid-state quantum systems, where it can be used as a sensitive tool to map the locations and characteristics of local fluctuators. In a different application, non-Gaussian noise spectroscopy will be used to improve nuclear spin detection using nitrogen vacancy centers in diamond. Multiqubit DDNS techniques will be developed to resolve multiple noise sources and to detect quantum noise in strongly coupled environments. These methods will be applied to study quantum models of interacting fluctuators, revisiting the spin-fluctuator model. The problem of two transverse noises will be analyzed under a general framework, accounting for both dephasing and dissipation, appropriate for a general qubit working point. The theory will be applied to the commonly encountered scenario of quantum dot singlet-triplet spin qubits simultaneously afflicted by charge and nuclear noises. Finally, venturing outside DDNS, other qubit-based methods for environmental noise characterization will be explored, including spin-locking based spectroscopy of continuously driven qubits and correlated projective measurements.The program supported through this award will be carried out at Santa Clara University and will provide educational opportunities for undergraduate students through independent research projects throughout its duration. Students at this primarily-undergraduate institution will become familiar with noise theory, semiconductor physics and foundational quantum mechanics, and will be exposed to a wide range of analytical and numerical methods. Because of the scientific and technological importance of these topics, students will benefit from a research experience that will prepare them for a wide variety of careers in academia and industry.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.