标题： 通过最优控制减少快速超导量子比特门的漏电 显示英文标题

标题： Leakage reduction in fast superconducting qubit gates via optimal control

摘要： 达到高速度、高保真度的量子比特操作需要对基本脉冲的形状进行精确控制。 对于弱非谐系统，如超导transmon量子比特，短门操作会导致计算子空间外的状态泄漏。 使用开环最优控制设计的控制脉冲可以减少这种泄漏。 然而，模型不准确可能会严重限制这些脉冲的可用性。 我们实现了一种闭环优化，根据由Clifford门构建的成本函数测量结果，同时适应所有控制参数。 通过使用与控制硬件能力相匹配的分段常数表示来参数化脉冲，我们创建了一个$4.16~\rm{ns}$单量子比特脉冲，其保真度为$99.76\,\%$，泄漏率为$0.044\,\%$。 这是我们在同一系统上对如此短持续时间的最佳DRAG脉冲泄漏率的七倍减少。 显示英文摘要

摘要： Reaching high speed, high fidelity qubit operations requires precise control over the shape of the underlying pulses. For weakly anharmonic systems, such as superconducting transmon qubits, short gates lead to leakage to states outside of the computational subspace. Control pulses designed with open-loop optimal control may reduce such leakage. However, model inaccuracies can severely limit the usability of such pulses. We implemented a closed-loop optimization that simultaneously adapts all control parameters based on measurements of a cost function built from Clifford gates. By parameterizing pulses with a piecewise-constant representation that matches the capabilities of the control hardware we create a $4.16~\rm{ns}$ single-qubit pulse with $99.76\,\%$ fidelity and $0.044\,\%$ leakage. This is a seven-fold reduction of the leakage rate of the best DRAG pulse we have calibrated at such short durations on the same system.