基于多比特超导量子芯片的量子调控与量子模拟

量子模拟利用完全理解的受控量子系统去模拟未知量子系统，它是量子计算有望在短期内实现的一类应用场景。多比特超导量子芯片因其易设计、易集成、易操控且近年来相干性能大幅提升等特点，成为实现实用化量子模拟技术的有力候选之一。它也是“第二代量子体系的构筑和操控”重大研究计划指南中“面向超导等固态量子计算的研究”所重点关注的内容。项目团队在相关科学技术领域包括超导量子芯片的设计制备和微波电子学集成控制电路开发等方面有长期的实践，协同攻关取得多项原创性科果，联合发表Science论文1篇。项目研究将以重大研究计划指南内容中所倡导的“极低温量子调控、测量技术的自主研发和集成”为本，围绕超导量子比特集成芯片的相干极限在哪里、量子操控保真度能否跟上芯片集成度的脚步，以及能否实现有潜在价值的量子模拟和算法等核心问题，研制集成约60比特的超导量子芯片并对其全局操控。项目立足于发展基于超导体系的实用化量子信息技术，着重考察几个关键指标的突破：超导量子芯片的比特集成数目达到60左右；芯片上量子比特的能量弛豫时间~50微秒，相位退相干时间~10微秒；研发高精度、可扩展的微波脉冲发生捕捉系统，两比特逻辑门保真度达到99.2%，且可同步测控60或更多比特。项目将基于多比特量子芯片和相应的测控硬件实现对多体局域化、拓扑物态等物理问题的量子模拟，尤其是理解多体系统涉及非平衡态和强关联的重要问题，实现高保真度的量子逻辑门，展现超导器件用于量子模拟研究的价值。

A quantum simulator uses a well-controlled quantum-mechanical device to mimic and investigate other unknown quantum systems, and it is likely to be realized in the near future as one of the showcases of quantum computation. Toward this goal, multiqubit superconducting circuits with continuously improved coherence provide a suitable building block, where conventional microchip fabrication can be used to take design concepts to experimental reality, quickly and flexibly, and microwave electronics can be integrated to implement quantum gate operations, promptly and precisely. Meanwhile, research on multiqubit superconducting circuits is one of the focuses of the major research plan "Fabrication and manipulation of the second-generation quantum systems". The two research groups in this project have been working jointly and diligently in the field of superconducting quantum simulation for more than three years, and up to now they have accumulated decisive experience in the development of the challenging quantum technologies such as designing and building up the superconducting quantum circuits as well as the associating microwave controlling electronics. Their joint scientific achievements include a high-quality paper published in Science. Here, the two groups are determined to co-develop a fully-controllable 60-qubit superconducting quantum circuit, with a focus on mastering the quantum control and measurement techniques at low temperatures as guided by the major research plan. During the development stage, core issues related to the quantum coherence limit of the multiqubit superconducting integrated circuits, the fidelity benchmark of the controlling gates, and the advantage of the quantum simulation algorithms will be explored. Key metrics characterizing the performance of the developed superconducting quantum circuit are expected, including the number of qubits (~ 60), the coherence of the qubits (T1 ~ 50 microseconds and T2 ~ 10 microseconds), and the fidelity of the two-qubit gates (~ 99.2%). Quantum simulation experiments with this 60-qubit circuit are expected to help improve our understanding of the transition from few-body to many-body physics and the interplay between non-equilibrium and strong correlations in many-body systems.