High-Fidelity Ternary Quantum Logic for Near-Term Algorithms

量子信息科学（QIS）正在进入噪声中尺度（NISQ）时代，执行超越经典计算能力的算法成为现实。nisq时代的量子计算机已经提出了影响几个领域的应用，从药物设计到资源分配优化。这项工作的关键是探索决定量子信息系统实现的特征和动力学的基础物理学，以及如何利用这种理解来改进量子控制。本项目的重点是通过利用超导电路的自然丰富结构来开发三元量子逻辑处理器，从而扩展现代处理器的资源效率。在QIS经历如此增长的情况下，招募和培训一支敬业和多样化的科学家队伍至关重要。该项目的研究将由研究生在高级人员的指导下进行，以获得未来学术和工业研究职业所需的技能。发展这一领域并不局限于已经涉足学术界的研究生。在一个暑期实习项目中，来自东湾地区当地高中的学生将被介绍到QIS研究中涉及的主题和技能，以及参与实践经验。这里的核心挑战是开发高保真的双量程（量子量程）门，这是产生纠缠和通用量子计算的基本成分。为了实现这一点，处理器利用可调耦合方案为快速门生成强交互，同时允许抑制不需要的交互。为了验证这些门技术，开发并采用了可扩展qutrit处理器基准测试，测量与多qutrit处理器兼容的最先进的保真度。最后，该处理器用于执行量子与经典混合算法，如量子近似优化算法（QAOA），该算法非常适合三元量子逻辑。nisq时代的算法特别利用三元逻辑，展示了这种处理器的强大功能，同时适应和开发必要的错误缓解技术，这对存在噪声的准确性至关重要。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 science (QIS) is entering the noisy intermediate-scale (NISQ) era, where executing algorithms that reach beyond classical computational capability becomes realistic. Applications impacting several fields, ranging from pharmaceutical design to resource allocation optimization, have been proposed for NISQ-era quantum computers. Vital towards this effort is an exploration of the fundamental physics determining the characteristics and dynamics of QIS implementations, and how this understanding can be utilized for improved quantum control. This project focuses on extending the resource efficiency of modern processors, by leveraging the naturally rich structure of superconducting circuits to develop a ternary quantum logic processor. With QIS experiencing such growth, it is essential to recruit and train an engaged and diverse workforce of scientists. Research for this project will be conducted by graduate students, with mentorship from senior personnel, gaining the skills required for future careers in academic and industrial research. Developing the field is not limited to graduate students already involved in academia. In a summer internship program, students from local East Bay Area high schools will be introduced to the topics and skills involved in QIS research, as well as engaging in hands-on experience.The central challenge here is development of high-fidelity two-qutrit (quantum trit) gates, an essential ingredient for generating entanglement and universal quantum computation. To accomplish this, the processor utilizes a tunable coupling scheme to generate strong interaction for fast gates, while allowing for suppression of unwanted interactions. To verify these gate techniques, scalable qutrit processor benchmarking is developed and employed, measuring state-of-the-art fidelities compatible with a multi-qutrit processor. Finally, the processor is used to execute hybrid quantum-classical algorithms, such as the quantum approximate optimization algorithm (QAOA), well suited to ternary quantum logic. NISQ-era algorithms specifically utilizing ternary logic demonstrate the power of such a processor, while adapting and developing necessary error mitigation techniques vital to accuracy in the presence of noise.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.