Title: Designing quantum experiments with a genetic algorithm Show Chinese title

Title: 用遗传算法设计量子实验

Abstract: We introduce a genetic algorithm that designs quantum optics experiments for engineering quantum states with specific properties. Our algorithm is powerful and flexible, and can easily be modified to find methods of engineering states for a range of applications. Here we focus on quantum metrology. First, we consider the noise-free case, and use the algorithm to find quantum states with a large quantum Fisher information (QFI). We find methods, which only involve experimental elements that are available with current or near-future technology, for engineering quantum states with up to a 100-fold improvement over the best classical state, and a 20-fold improvement over the optimal Gaussian state. Such states are a superposition of the vacuum with a large number of photons (around $80$), and can hence be seen as Schr\"odinger-cat-like states. We then apply the two most dominant noise sources in our setting -- photon loss and imperfect heralding -- and use the algorithm to find quantum states that still improve over the optimal Gaussian state with realistic levels of noise. This will open up experimental and technological work in using exotic non-Gaussian states for quantum-enhanced phase measurements. Finally, we use the Bayesian mean square error to look beyond the regime of validity of the QFI, finding quantum states with precision enhancements over the alternatives even when the experiment operates in the regime of limited data. Show Chinese abstract

Abstract: 我们介绍了一种遗传算法，用于设计量子光学实验，以工程化具有特定特性的量子态。 我们的算法功能强大且灵活，可以轻松修改以找到适用于各种应用的工程化状态的方法。 在这里，我们专注于量子计量学。 首先，我们考虑无噪声的情况，并使用该算法寻找具有较大量子费舍尔信息（QFI）的量子态。 我们找到了方法，这些方法仅涉及当前或近期技术可实现的实验元件，用于工程化量子态，其性能比最佳经典态提高多达100倍，比最优高斯态提高20倍。 这类态是真空与大量光子（约$80$）的叠加态，因此可以看作是薛定谔猫态。 然后，我们将设置中两种最主要的噪声源——光子损耗和不完善的探测信号——应用于算法，以找到在现实噪声水平下仍优于最优高斯态的量子态。 这将为利用奇特的非高斯态进行量子增强相位测量的实验和技术工作开辟新的方向。 最后，我们使用贝叶斯均方误差来超越QFI的有效性范围，发现即使在实验处于数据有限的范围内，这些量子态仍能实现对其他方法的精度提升。