通过快速加载和快速清除读出减轻测量诱导的状态转变
Mitigation of Measurement-Induced State Transitions via a Fast-Load and Fast-Clear Readout
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中文总结 AI 辅助
研究超导量子处理器中测量诱导状态转变问题，通过设计快速加载和快速清除脉冲抑制谐振器光子过冲，无需复杂波形或实时反馈，评估读出和读出后阶段误差概率，验证三步脉冲方案可最小化读出误差，实现更好权衡。
中文摘要 AI 辅助
高保真和快速的量子比特读出对于超导量子处理器至关重要，通常通过量子比特-谐振器架构内的量子非破坏（QND）色散相互作用实现。然而，可实现的读出速度和保真度受到测量诱导的状态转变（MIST）的根本限制。对于跨导量子比特，由于其高能级的电荷色散，MIST对偏置电荷$n_g$高度敏感。在这项工作中，我们系统地研究了电荷敏感跨导架构内由脉冲整形的非绝热性和对称性控制的与$n_g$相关的MIST动力学。我们设计了快速加载和快速清除脉冲，有效抑制谐振器光子过冲，展示了一种无需复杂波形或实时反馈即可减轻MIST的实用策略。利用有源栅极电压控制和快速反馈，测量诱导的跃迁概率精确地映射到$n_g$和稳态谐振器光子数上，与数值弗洛凯分支分析高度一致。最终，我们评估了读出和读出后阶段的$n_g$平均总误差概率，验证了一个简单的三步脉冲方案始终能最小化整体读出误差。在大规模超导量子处理器框架内，这种实用的、无需硬件的方法在读出信噪比和QND保持之间固有地提供了更好的权衡。
英文摘要
High-fidelity and rapid qubit readout is essential for superconducting quantum processors, typically realized through the quantum non-demolition (QND) dispersive interaction within a qubit-resonator architecture. However, the achievable readout speed and fidelity are fundamentally limited by measurement-induced state transitions (MIST). For a transmon qubit, MIST is highly sensitive to the offset charge $n_g$ due to the charge dispersion of its higher-lying energy levels. In this work, we systematically investigate $n_g$-dependent MIST dynamics governed by the diabaticity and symmetry of pulse shaping within a charge-sensitive transmon architecture. We engineer fast-load and fast-clear pulses that effectively suppress resonator photon overshoots, thereby demonstrating a highly practical strategy to mitigate MIST without requiring complex waveforms or real-time feedback. Utilizing active gate-voltage control and rapid feedback, the measurement-induced transition probability is precisely mapped against $n_g$ and the steady-state resonator photon number, exhibiting strong agreement with numerical Floquet branch analysis. Ultimately, we evaluate the $n_g$-averaged total error probabilities for both readout and post-readout stages, verifying that a straightforward three-step pulse scheme consistently minimizes overall readout errors. Within the framework of large-scale superconducting quantum processors, this practical, hardware-free approach inherently offers a better trade-off between the readout signal-to-noise ratio and QND preservation.
