在单个实验中同时校准旋转和相位误差
Simultaneous calibration of rotation and phase errors in a single experiment
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中文总结 AI 辅助
研究弱非谐量子比特中相干控制误差，提出用单个参数化实现 DRAPE 协议同时校准旋转和相位误差，通过实验校准 IBM 传输子的 $\pi/2$ 门，有效降低了过旋转和相位误差。
中文摘要 AI 辅助
在弱非谐量子比特中，相干控制误差有过/欠旋转和相位误差两种常见形式，通常需要迭代实验来抑制。本文表明，对于弱驱动 regime 中的任何对称 $\pi/2$ 脉冲，两者都源于单个参数化 $\mathcal{X}(\pi/2)=Z(\delta)X(\pi/2+\epsilon)Z(\delta)$，该参数化将旋转误差 $\epsilon$ 和相位误差 $\delta$ 直接与系统参数联系起来。这种参数化实现了 DRAPE，一种 Ramsey 型协议，通过扫描相位误差校正可揭示一个交叉点，能同时确定两个校正。相位校正用海森堡标度估计，旋转误差达到标准量子极限。我们通过校准 IBM 传输子的 $|1\rangle\leftrightarrow |2\rangle$ 跃迁上的 $\pi/2$ 门，实验演示了 DRAPE，将每个门的过旋转从 $0.997^\circ$ 降低到 $-0.007^\circ$，相位误差从 $2.52^\circ$ 降低到 $0.0052^\circ$，并通过相位和旋转误差放大协议独立验证。
英文摘要
In weakly anharmonic qubits, coherent control errors take two generic forms -- over/under-rotation and phase errors -- whose suppression normally requires iterated experiments. We show that, for any symmetric $π/2$ pulse in the weak-driving regime, both follow from a single parametrization, $\mathcal{X}(π/2)=Z(δ)X(π/2+ε)Z(δ)$, that ties the rotation error $ε$ and the phase error $δ$ directly to the system parameters. The parametrization enables DRAPE, a Ramsey-type protocol in which sweeping the phase-error correction reveals a crossing point that fixes both corrections at once. The phase correction is estimated with Heisenberg scaling while the rotation error saturates the standard quantum limit. We experimentally demonstrate DRAPE by calibrating a $π/2$ gate on the $|1\rangle\leftrightarrow |2\rangle$ transition of an IBM transmon, reducing the over-rotation from $0.997^\circ$ to $-0.007^\circ$ and the phase error from $2.52^\circ$ to $0.0052^\circ$ per gate, validated independently by phase- and rotation-error amplification protocols.
