NSF-NSERC: Building a two-qubit controlled phase gate using laterally coupled semiconductor quantum dots

NSF-NSERC：使用横向耦合半导体量子点构建两个量子位控制的相位门

• 批准号: 2317047
• 负责人: Pei-Cheng Ku
• 金额: $ 36.23万
• 依托单位: Regents of the University of Michigan - Ann Arbor
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-08-15 至 2026-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2317047&HistoricalAwards=false
• 关键词: NSF; NSERC; Building; two; qubit

Quantum bit or qubit is the basic building block for quantum science and information processing. The ability to generate, process, and store qubits establishes the foundation for quantum information science and technologies. This collaborative project aims to investigate the interaction between two qubits in a semiconductor system which has been the technology of choice to this date for information processing, communication, and storage. Semiconductor quantum dots are atom-like man-made structures that have been shown to generate and store qubits efficiently. Moreover, quantum dot qubits can seamlessly interface with light to transmit quantum information over a distance. As a result, there have been tremendous interests in exploring quantum dot qubits as the fundamental building block for a future quantum computing or communication system. One critical yet missing link is the ability to process two quantum dot qubits deterministically. This project aims to fill the technological gap by creating two site-controlled quantum dots in a proximity and exploiting the interaction between them. Positive results of this project not only can advance the knowledge of using a semiconductor system for quantum information science and engineering but also develop highly trained engineers and scientists. Isolated electron spins in semiconductor quantum dots have robust coherence; therefore, they are promising qubit candidates for a solid-state quantum system. Heterostructure quantum dot spins can be easily interfaced with photonic qubits, making them especially attractive for quantum network applications. Significant advances have been made in implementing single-qubit operations in heterostructural quantum dots. Further extension of the ability to a two-qubit gate is crucial to enable quantum computational functionalities, e.g., entanglement swapping in a quantum link and generation of the large-scale entangled cluster state. The proposed research focuses on improving a quantum spin-spin gate in heterostructural quantum dots. While an experimental proof-of-concept two-qubit spin gate has been reported recently in a vertically stacked quantum dot structure. However, the coupling mediated by the exchange interaction between two electron spins is not transient, limiting its applicability to general-purpose computational needs. There are also practical challenges in precisely aligning the energy levels between the two quantum dots, which share a common electrical path. This research aims to eliminate these issues by using laterally positioned quantum dots coupled via long-range and on-demand Coulomb interaction. The proposed study builds upon the recent theoretical demonstration of a spin-spin gate between two laterally positioned nitride semiconductor quantum dots, focusing on pushing the boundary of group III-nitride quantum dot growth to experimentally demonstrate a reliable process to create laterally positioned quantum dot pairs with a varying interdot spacing, a transient Coulomb coupling between the dots, and a controlled phase gate between two electron spins.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.

量子比特或量子比特是量子科学和信息处理的基本构建块。生成、处理和存储量子比特的能力为量子信息科学和技术奠定了基础。该合作项目旨在研究半导体系统中两个量子位之间的相互作用，该系统迄今为止一直是信息处理，通信和存储的首选技术。半导体量子点是类原子的人造结构，已被证明可以有效地产生和存储量子比特。此外，量子点量子比特可以与光无缝连接，以远距离传输量子信息。因此，人们对探索量子点量子比特作为未来量子计算或通信系统的基本构建块产生了巨大的兴趣。一个关键但缺失的环节是确定性地处理两个量子点量子比特的能力。该项目旨在通过在附近创建两个位点控制的量子点并利用它们之间的相互作用来填补技术空白。该项目的积极成果不仅可以促进将半导体系统用于量子信息科学和工程的知识，还可以培养训练有素的工程师和科学家。半导体量子点中的孤立电子自旋具有强大的相干性;因此，它们是固态量子系统的有希望的量子比特候选者。 异质结构量子点自旋可以很容易地与光子量子比特连接，使它们对量子网络应用特别有吸引力。在异质结构量子点中实现单量子比特操作已经取得了重大进展。进一步扩展到两量子比特门的能力对于实现量子计算功能至关重要，例如，量子链中的纠缠交换和大尺度纠缠团簇态的产生。本论文的研究重点是改进异质结构量子点中的量子自旋-自旋门。而最近在垂直堆叠的量子点结构中已经报道了实验性的概念验证的双量子比特自旋门。然而，由两个电子自旋之间的交换相互作用介导的耦合不是瞬态的，限制了其适用于通用计算需求。此外，在精确对齐两个量子点之间的能级方面也存在实际挑战，这两个量子点共享一个共同的电路径。本研究旨在通过使用横向定位的量子点通过远程和按需库仑相互作用耦合来消除这些问题。所提出的研究建立在最近的两个横向定位的氮化物半导体量子点之间的自旋-自旋门的理论证明的基础上，重点是推动III族氮化物量子点生长的边界，以实验证明一种可靠的方法来创建具有变化的点间间距的横向定位的量子点对，点之间的瞬时库仑耦合，该奖项反映了NSF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。