AI 中文总结
该研究针对硅自旋量子比特受驱相干性波动导致门保真度难以稳定提升的问题，通过移除邻近储层延长$T_{1ρ}$、优化器件与定制脉冲抑制非共振效应，实现了99.99920(2)%的π/2门保真度，明确了保真度限制机制并给出高保真实现方案。
AI 中文摘要
在半导体单自旋量子比特中，高保真度量子门已得到验证；然而，由于受驱量子比特相干性的波动，实现稳定的性能仍具挑战性，相较于$T_2^*$等自由演化相干性，学界对受驱相干性的探索较少。本文报道了通过大幅延长受驱自旋相干时间、抑制对准确保真度基准测试有害的非共振驱动效应，实现了高于99.999%的单量子比特门保真度。我们证明，移除邻近的储层可显著提升自旋锁定相干时间（$T_{1ρ}$）——这是微波驱动下量子比特的一项关键指标。此外，我们揭示，在采用奇偶校验读出和矩形脉冲的典型自旋量子比特装置中，相邻量子比特的非共振激发会引发显著的基准测试伪影。通过优化器件条件以缓解微波诱导的退化，并采用频谱定制的脉冲整形技术，我们实现了99.99920(2)%的π/2门保真度，剩余误差主要受非相干噪声限制。这些结果阐明了制约先进硅自旋量子比特保真度基准测试的机制，并为在这类系统中实现及验证高保真度提供了实用指导。
英文摘要
In semiconductor single-spin qubits, high-fidelity quantum gates have been demonstrated; however, achieving consistent performance remains challenging due to variations in driven qubit coherence, which is less explored than free-evolution coherence such as $T_2^*$. Here, we report single-qubit gate fidelities above 99.999%, achieved by dramatically extending the driven-spin coherence time and suppressing off-resonant driving effects that are detrimental to accurate fidelity benchmarking. We demonstrate that removing proximal reservoirs significantly enhances the spin-locking coherence time ($T_{1ρ}$), a critical metric for qubits under microwave driving. Furthermore, we reveal that in typical spin qubit setups using parity readout and rectangular pulses, off-resonant excitation of neighboring qubits causes substantial benchmarking artifacts. By optimizing device conditions to mitigate microwave-induced degradation and implementing spectrally tailored pulse shaping, we achieve a $π/2$ gate fidelity of 99.99920(2)%, with remaining errors primarily limited by incoherent noise. These results showcase the mechanisms that bound fidelity benchmarking in state-of-the-art silicon spin qubits and provide practical guidelines for achieving and verifying high fidelities in these systems.
