论文标题
统计表征量子控制和量子控制算法的鲁棒性和忠诚度
Statistically Characterising Robustness and Fidelity of Quantum Controls and Quantum Control Algorithms
论文作者
论文摘要
量子操作或控件的鲁棒性对于构建可靠的量子设备很重要。引入了稳健性 - 融合度度量(RIM $ _P $),以统计量化控制器的鲁棒性和忠诚度,因为在任何不确定性和理想的忠诚度分布下,控制器的保真度分布之间的P级Wasserstein距离。 RIM $ _P $是不忠发行的P-thr原始力矩的第三个根。使用Metrrization参数,我们证明了为什么RIM $ _1 $(平均不忠)足以作为一种实用的鲁棒性度量。基于RIM $ _P $,开发了算法鲁棒性侵线度量(ARIM),以量化控制算法发现的控制器的预期鲁棒性和忠诚度。通过考虑对旋转 - $ \ tfrac {1} {2} $网络的稳健控制的问题,使用能量景观塑形来证明轮辋和ARIM的效用。表征了各个流行量子控制算法的单个控制解决方案的鲁棒性和忠诚度以及预期的鲁棒性和忠诚度。为了进行算法比较,考虑了随机和非策略优化目标,目的是在后者中有效优化。尽管高保真度和鲁棒性通常是相互矛盾的目标,但通常可以找到一些高保真,健壮的控制器,而与量子控制算法的选择无关。但是,对于嘈杂的优化目标,与标准对照算法相比,适应性的顺序决策方法(例如增强学习)具有成本优势,相反,获得的不忠与低噪声水平的RIM值更一致。
Robustness of quantum operations or controls is important to build reliable quantum devices. The robustness-infidelity measure (RIM$_p$) is introduced to statistically quantify the robustness and fidelity of a controller as the p-order Wasserstein distance between the fidelity distribution of the controller under any uncertainty and an ideal fidelity distribution. The RIM$_p$ is the p-th root of the p-th raw moment of the infidelity distribution. Using a metrization argument, we justify why RIM$_1$ (the average infidelity) suffices as a practical robustness measure. Based on the RIM$_p$, an algorithmic robustness-infidelity measure (ARIM) is developed to quantify the expected robustness and fidelity of controllers found by a control algorithm. The utility of the RIM and ARIM is demonstrated by considering the problem of robust control of spin-$\tfrac{1}{2}$ networks using energy landscape shaping subject to Hamiltonian uncertainty. The robustness and fidelity of individual control solutions as well as the expected robustness and fidelity of controllers found by different popular quantum control algorithms are characterized. For algorithm comparisons, stochastic and non-stochastic optimization objectives are considered, with the goal of effective RIM optimization in the latter. Although high fidelity and robustness are often conflicting objectives, some high fidelity, robust controllers can usually be found, irrespective of the choice of the quantum control algorithm. However, for noisy optimization objectives, adaptive sequential decision making approaches such as reinforcement learning have a cost advantage compared to standard control algorithms and, in contrast, the infidelities obtained are more consistent with higher RIM values for low noise levels.