AI 中文总结
研究快速跨导单比特门泄漏问题，提出路径 - 终点分离脉冲（PESP），将泄漏抑制分为路径整形脉冲抑制暴露和双音终点抵消脉冲消除残余幅度，有效降低去相位泄漏和相干残余误差，使泄漏抑制成模块化可解释控制问题。
AI 中文摘要
弱非谐跨导上的快速单比特门受限于向非计算态的泄漏，标准缓解措施如DRAG作用于门结束时的泄漏幅度。我们表明，该终点幅度和门期间积累的瞬态泄漏暴露是两个不同的控制目标，可分配给单独模块。终点是驱动频谱的单个样本$|\tilde\Lambda(\eta)|^2$；暴露是关于$\eta$的带积分并控制去相位下的泄漏，频谱零条件$\tilde\Lambda(\eta)=0$仅约束前者。我们在路径 - 终点分离脉冲（PESP）中实现了这种分离：路径整形脉冲抑制暴露，双音终点抵消脉冲消除残余幅度。对于在$\eta/2\pi = 0.2$GHz下的10ns $R_{X}(\pi/2)$门，数值模拟中路径整形脉冲相对于余弦DRAG将去相位暴露降低约21%，相对于独立模拟的林德布拉德过量泄漏降低约20%。残余终点底部分解为$|2\rangle$反作用和$|3\rangle$级联，双音将其一对一抵消，将路径暴露拐点处的底部从约$7\times10^{-7}$驱动到约$3\times10^{-8}$而不干扰路径。通过分离瞬态暴露与终点泄漏，PESP将快速弱非谐门中的泄漏抑制转变为模块化、可解释的控制问题：去相位引起的泄漏和相干残余误差由单独的、可单独验证的模块降低。
英文摘要
Leakage to noncomputational states limits the speed of single-qubit gates in weakly anharmonic transmons. Conventional pulse-shaping methods, including derivative removal by adiabatic gate (DRAG), primarily suppress the leakage remaining at the end of a gate. Here we demonstrate that endpoint leakage and the transient leakage population that accumulates during the gate represent distinct control objectives. Endpoint leakage is associated with the drive spectrum at the anharmonicity, whereas transient exposure depends on spectral weight over a finite frequency band and governs the additional leakage induced by dephasing. A spectral null at the leakage transition therefore suppresses the endpoint amplitude without necessarily reducing transient exposure. Based on this distinction, we introduce a path--endpoint separation pulse that combines transient-path shaping with a two-tone endpoint correction. For a $10$ ns $R_X(π/2)$ gate with an anharmonicity magnitude of $0.2$ GHz, numerical simulations show a $21\%$ reduction in transient exposure relative to cosine DRAG and a corresponding $20\%$ reduction in dephasing-induced excess leakage. The two correction tones further suppress residual leakage through the $|2\rangle$ and $|3\rangle$ channels, lowering the coherent endpoint leakage from approximately $7\times10^{-7}$ to $3\times10^{-8}$ without increasing transient exposure. These results establish transient exposure and endpoint leakage as complementary targets for the design of fast transmon gates.
