Collaborative Research: Physics and Quantum Technology Applications of Defects in Silicon Carbide

该奖项支持用于量子计算的材料缺陷的理论和计算研究。碳化硅由于其工业上的成熟和与当前电子器件制造的兼容性，是一种很有前途的量子信息处理材料。缺陷是指在完美的碳化硅晶体中，硅和碳原子的完美规则排列被破坏。有希望的缺陷包括空缺，如硅原子在预期的位置上缺失或相邻位置上缺失硅和碳原子；一个氮原子的存在和一个相关的空位。电子被限制在一个小体积内的量子力学状态。这些状态可以被初始化、操纵和测量；它们是量子比特的有希望的候选者，量子比特是普通计算机中比特的量子计算机类似物。碳化硅中的缺陷在一系列应用中具有吸引人的特性，包括量子增强的电场和磁场传感，长距离安全量子通信以及量子计算。pi将开发理论工具来理解和利用碳化硅中最有前途的缺陷，并评估其应用潜力。特别是，pi将使用计算技术和分析理论计算这些缺陷在与激光和静电场相互作用下的动力学。这项工作将为传感应用铺平道路。发射光的特性也将被研究，这将导致为远程量子通信网络设计新的光-物质接口。将计算缺陷及其环境（包括核模式和振动模式）之间的相互作用，并评估它们对缺陷性能的影响。pi还将研究控制这些量子系统的新方法。这项研究的结果将有助于开发基于碳化硅的系统，以实现强大的未来量子信息技术。该项目还将有助于教育和支持下一代量子信息科学与技术研究人员。该奖项支持理论和计算研究和教育，使用第一性原理技术来研究碳化硅缺陷的物理和动力学，包括通过系统间交叉的自旋极化过程以及用于传感和自旋控制应用的电场耦合。一个动态核极化计算的形式将被发展，以理解现有的实验，并揭示中心自旋耦合到两个不同的核槽的独特物理。将评估用于量子通信和中继器的碳化硅器件的可行性。具体来说，该项目将通过考虑状态的混合和从第一性原理计算中获得的振动模式的耦合来表征量子信息应用的自旋光子界面。除了量子比特的自旋控制技术之外，还将开发利用S=3/2的硅空位中心的自旋控制技术。本课题的理论结果将与实验数据进行对比，促进进一步的实验研究。该项目还将有助于教育和支持下一代量子信息科学与技术研究人员。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。

NONTECHNICAL SUMMARYThis award supports theoretical and computational research on defects in materials that are good candidates to be used for quantum computing. Silicon carbide is a promising material for quantum information processing due to its maturity in industry and compatibility with current electronic device fabrication. Defects refer to disruptions in the perfect regular array of silicon and carbon atoms in a perfect silicon carbide crystal. Promising defects include vacancies such as a silicon atom missing from a site where it is expected or a missing silicon and missing carbon atom on neighboring sites; and the presence of a nitrogen atom along with an associated vacant site. Electrons are confined to quantum mechanical states localized in a small volume. These states can be initialized, manipulated, and measured; they are promising candidates for qubits which are the quantum computer analogs of bits in ordinary computers. Defects in silicon carbide have attractive properties for a range of applications, including quantum-enhanced sensing of electric and magnetic fields, secure quantum communications over long distances, as well as quantum computation. The PIs will develop theoretical tools to understand and exploit the most promising defects in silicon carbide and assess their potential for applications. In particular, the PIs will calculate the dynamics of these defects under interaction with lasers and with static electric fields, using both computational techniques and analytical theory. This work will pave the way toward sensing applications. The properties of the emitted light will also be studied, which will lead to the design of new light-matter interfaces for long-range quantum communication networks. The interactions between the defects and their environment, including the nuclear and vibrational modes, will be calculated, and their effect on the performance of the defect will be assessed. The PIs will also investigate new ways of controlling these quantum systems. The outcomes of this research will contribute toward the development of silicon carbide based systems for powerful future quantum information technologies. This project will also contribute to educating and supporting the next generation of researchers in quantum information science and technology. Technical summaryThis award supports theoretical and computational research and education to use first principles techniques to investigate the physics and dynamics of defects in silicon carbide, including the process of spin polarization through intersystem crossing and the coupling to electric fields for sensing and spin control applications. A formalism for dynamic nuclear polarization calculations will be developed to understand existing experiments and to reveal the distinct physics of a central spin coupled to two distinct nuclear baths. The viability of silicon carbide devices for quantum communications and repeaters will be assessed. Specifically, this project will characterize spin-photon interfaces for quantum information applications by taking into account mixings of states and couplings to vibrational modes obtained from first principles calculations. Spin control techniques beyond those for qubits will be developed to exploit the silicon vacancy center with S=3/2. The theoretical results of this project will be compared to experimental data and stimulate further experimental studies. This project will also contribute to educating and supporting the next generation of researchers in quantum information science and technology.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.