Experimentally achieving the precision that standard quantum metrology schemes promise is always challenging. Recently, additional controls were applied to design feasible quantum metrology schemes. However, these approaches generally does not consider ease of implementation, raising technological barriers impeding its realization. In this paper, we circumvent this problem by applying closed-loop learning control to propose a practical controlled sequential scheme for quantum metrology. Purity loss of the probe state, which relates to quantum Fisher information, is measured efficiently as the fitness to guide the learning loop. We confirm its feasibility and certain superiorities over standard quantum metrology schemes by numerical analysis and proof-of-principle experiments in a nuclear magnetic resonance system.

实验上达到标准量子计量方案所承诺的精度始终具有挑战性。最近，附加的控件被应用于设计可行的量子计量方案。但是，这些方法通常不考虑易于实施，从而增加了阻碍其实现的技术障碍。在本文中，我们通过应用闭环学习控制为量子计量学提出了一种实用的受控顺序方案，从而规避了这一问题。与量子费舍尔信息有关的探针状态的纯度损失被有效地测量为指导学习循环的适应性。通过在核磁共振系统中的数值分析和原理证明实验，我们证实了其相对于标准量子计量方案的可行性和某些优势。