发表机构
Università dell’Aquila; INFN, Laboratori Nazionali del Gran Sasso（阿奎拉大学; 意大利国家核物理研究所，大萨索国家实验室）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究通过弗洛凯理论结合CMA-ES优化，在3至7位点超导线性链中实现高保真量子门合成，解决多量子比特控制瓶颈，搭建周期控制理论与量子门工程的桥梁。
AI 中文摘要
对超导量子处理器而言，多量子比特架构的精准控制仍是关键瓶颈。本研究在扩展的超导线性链（规模从3个位点到7个位点）中探究高保真量子操作与态转移协议的合成方法。借助弗洛凯理论，我们将周期驱动建模为类δ脉冲序列，把量子控制问题映射为准能共振条件。结合贝克-坎贝尔-豪斯多夫展开与弗洛凯谱分解，我们解析确定最优驱动参数，再通过协方差矩阵自适应进化策略（CMA-ES）进行优化。在3量子比特架构中，该方法可实现iSWAP门的高保真合成；扩展至7位点链时，我们采用有限宽度高斯脉冲的周期序列，激活具有超短门时长（t_gate≈170 ns）的不同双激发输运通道。这一结果与采用可调耦合器的固定频率transmon器件（如IBM Quantum硬件）典型的能量弛豫时间（T1）形成明确的尺度分离。最后，我们在实际缺陷下对稳定性进行基准测试，发现受谱拥挤效应影响，器件对亚百分比级（η≈10^-3）的静态参数无序具有更高敏感性，并探讨闭环拓扑结构如何缓解该约束。该框架搭建了时间周期控制理论与实用量子门工程之间的桥梁。
英文摘要
Precise control of multi-qubit architectures remains a critical bottleneck in superconducting quantum processors. In this work, we investigate the synthesis of high-fidelity quantum operations and state transfer protocols within an extended superconducting linear chain, scaling from three to seven sites. Using Floquet theory, we model the periodic drive as a train of delta-like pulses, mapping the quantum control problem onto quasi-energy resonance conditions. Combining the Baker-Campbell-Hausdorff expansion with Floquet spectral decomposition, we analytically identify optimal driving parameters, refined via the Covariance Matrix Adaptation Evolution Strategy (CMA-ES). In the three-qubit architecture, this enables high-fidelity synthesis of the iSWAP gate. Extending to a seven-site chain, we implement periodic trains of finite-width Gaussian pulses to activate distinct double-excitation transport channels with ultra-short gate durations t_gate (~170 ns). This achieves a clear scale separation from energy-relaxation times (T1) typical of fixed-frequency transmon devices with tunable couplers, such as IBM Quantum hardware. Finally, we benchmark stability under realistic imperfections, revealing a heightened sensitivity to static parameter disorder at the sub-percent level (eta ~ 10^-3) driven by spectral crowding, and discuss how closed-loop topologies could mitigate this constraint. This framework bridges time-periodic control theory and practical quantum gate engineering.
Comments15 pages, 9 figures, appendices, Code and data available upon request
