We study the effect of feedback controls in quantum parameter estimation. In particular, we study the estimation of a magnetic field with a spin in the presence of the spontaneous emission where feedback control, triggered by the detection of the emitted photons, is employed to improve the precision limit. We also study the effect of additional Hamiltonian controls and show that they can provide further improvement on the precision limit.

中文翻译：

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通过反馈控制实现量子参数估计的更高精度

我们研究了反馈控制在量子参数估计中的作用。特别是，我们研究了自发辐射存在时自旋磁场的估计，其中通过检测发射的光子来触发反馈控制，以提高精度极限。我们还研究了附加哈密顿控制的效果，并表明它们可以在精度极限上提供进一步的改进。