EAGER: Deterministic Placement of Qubits in Cavities for Strongly Coupled Quantum Repeaters

EAGER：强耦合量子中继器腔体中量子位的确定性放置

• 批准号: 1748106
• 负责人: Evelyn Hu
• 金额: $ 30万
• 依托单位: Harvard University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-08-15 至 2020-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1748106&HistoricalAwards=false
• 关键词: EAGER; Deterministic; Placement; Qubits; Cavities

This EAGER project on Deterministic Placement of Qubits in Cavities for Strongly-Coupled Quantum Repeaters studies ways of optimally placing qubits within specially engineered environments (cavities) that will allow us to store, amplify and control the release of information contained by the qubit. Qubits, corresponding to quantum mechanical states, are the fundamental units of information in system where the rules of quantum mechanics explicitly govern the exchange, storage and transmission of information. Qubits within quantum systems hold great promise for faster, more secure processing and transmission of complex information, but there are profound, fundamental challenges that limit the longevity, storage and signal strength of qubit information. The use of specially-designed cavities can result in substantial amplification of qubit optical signals, allow storage of qubit information and provide a means of controlled transmission of the qubit information: such strongly coupled qubit-cavity systems can provide an important building block of larger-scale quantum information systems. A major challenge here lies in the optimal placement of the qubit within the cavity: the efficacy of the cavity can fall off dramatically with misalignments of only several atomic lattice distances. The research proposed here uses a semiconductor platform, developing sensitive means of fine-tuning the placement of atomic-scale qubits within the cavity, and using the amplified signals from the qubit-cavity system itself to guide the process. The knowledge gained from this research can have a profound and wide-ranging impact on a variety of qubit-cavity systems, bringing us much closer to achieving robust, scalable quantum information systems on a semiconductor "chip".Technical Description: The proposed EAGER project on Deterministic Placement of Qubits in Cavities for Strongly-Coupled Quantum Repeaters will build on exciting results observed in prior experiments involving Silicon Vacancies in 4H-SiC nanobridge cavities. These experiments suggest the possibility of deterministically placing defect-based qubits in spatial overlap with the maxima of the electromagnetic fields (modes) of the cavity, one of the greatest challenges in achieving strong coupling of qubit and cavity. The work of this project develops and tests a number of strategies to achieve better control over the diffusive motion of these defect-based qubits. To understand and interpret the placement process, a detailed understanding is required of the energy landscape of the qubit, and its sensitivity to thermal, electronic and strain variations; thus a collaborative effort between experiment and theory is mandatory for success. Therefore, the proposed work closely couples experiments, complemented and guided by theoretical simulations. The research team evaluates thermal control of the diffusion process, as well as the more localized and potentially better-controlled radiation enhanced diffusion processes. The team also explores the possibility of a self-aligned process, using the high field (modal) region of the cavity itself. Achieving the correct spatial overlap of qubit to the maximum field in a cavity is perhaps the greatest challenge to attaining strong coupling. Therefore, the studies proposed here will have a significant, wide-spread impact on creating scalable quantum information systems, across a broad spectral range. The resulting strongly coupled qubit-cavity devices can serve as effective quantum repeaters that link information from discrete, spatially-separated qubits across a network. Moreover, the collaborative and closely-coupled interaction between theory and experiment represented by this team provides a richer and more complete research and education environment, as well as setting benchmarks for how such challenging problems can and should be addressed.

这个关于强耦合量子中继器腔中量子位的确定性放置的EAGER项目研究了在特殊工程环境（腔）中最佳放置量子位的方法，这将使我们能够存储，放大和控制量子位所包含的信息的释放。量子比特对应于量子力学状态，是系统中信息的基本单位，量子力学规则明确支配信息的交换、存储和传输。量子系统中的量子比特在更快、更安全地处理和传输复杂信息方面有着巨大的潜力，但也存在着深刻的、根本性的挑战，限制了量子比特信息的寿命、存储和信号强度。使用特殊设计的腔可以导致量子比特光信号的大幅放大，允许量子比特信息的存储，并提供量子比特信息的受控传输的手段：这种强耦合的量子比特-腔系统可以提供更大规模量子信息系统的重要构建块。这里的一个主要挑战在于量子位在腔体内的最佳放置：只要有几个原子晶格距离的错位，腔的功效就会急剧下降。这里提出的研究使用半导体平台，开发精细调整腔体内原子级量子位的位置的灵敏方法，并使用来自量子位腔系统本身的放大信号来指导这一过程。从这项研究中获得的知识可以对各种量子位腔系统产生深远而广泛的影响，使我们更接近于在半导体“芯片”上实现强大的可扩展量子信息系统。技术描述：拟议的EAGER项目关于强-耦合量子中继器将建立在先前实验中观察到的令人兴奋的结果，这些实验涉及4 H-SiC纳米桥腔中的硅空位。这些实验表明，有可能确定性地将基于缺陷的量子位与腔的电磁场（模式）的最大值空间重叠，这是实现量子位和腔的强耦合的最大挑战之一。该项目的工作开发和测试了一些策略，以更好地控制这些基于缺陷的量子位的扩散运动。为了理解和解释放置过程，需要详细了解量子位的能量分布，以及它对热、电子和应变变化的敏感性;因此，实验和理论之间的合作是成功的必要条件。因此，所提出的工作密切耦合实验，补充和指导理论模拟。研究小组评估了扩散过程的热控制，以及更局部化和可能更好地控制辐射增强扩散过程。该团队还探索了自对准过程的可能性，使用腔体本身的高场（模态）区域。实现量子位与腔中最大场的正确空间重叠可能是实现强耦合的最大挑战。因此，本文提出的研究将对创建可扩展的量子信息系统产生重大而广泛的影响。由此产生的强耦合量子位腔器件可以作为有效的量子中继器，将来自离散的、空间分离的量子位的信息链接到网络中。此外，该团队所代表的理论与实验之间的协作和紧密耦合的互动提供了更丰富，更完整的研究和教育环境，并为如何解决这些具有挑战性的问题设定了基准。