基于光子自旋霍尔效应的弱测量研究

The photonic spin Hall effect (SHE) is a sensitive physical phenomenon which is sensitive to the structure parameter variations of physical systems, and therefore it holds great potential application for precision metrology. Generally, the spin-dependent splitting in photonic SHE is very small. So the weak measurements method is used to detect it. However, the present weak measurement theory of photonic SHE has limitations. When the degree of coupling between the observable and the measuring device is strong or the preselected and postselected are close to the orthogonal states, the theory and experiment show large deviation so that the accuracy for determining the structure parameters of physical systems is significantly affected. In this project, from the basic weak measurement theory of photonic SHE, we further explore of the physical meaning of the weak value in these two special conditions and make the corresponding modifications. We also design different experiments based on weak value and spin-dependent splitting to verify our proposals. These findings will not only improve the detection accuracy of photonic SHE in precision metrology but also provide theoretical guidance and experimental evidence for developing new spin-based nanophotonics devices.

光子自旋霍尔效应是一种灵敏的物理现象，它对于物理系统中结构参数的变化非常敏感，因而其在精密测量领域具有潜在的应用价值。一般来说光子自旋霍尔效应所产生的自旋分裂值很小，需要通过弱测量的方法才能对其进行有效探测。但现有基于光子自旋霍尔效应的弱测量理论具有局限性，当系统被观测量与测量仪器之间的耦合程度较强或前选择态与后选择态接近完全正交时，理论与实验偏差较大，因而影响其在综合判断物理系统中结构参数大小时的准确度。在本申请项目中，我们提出在已有基于光子自旋霍尔效应的弱测量理论基础之上，进一步探索在特殊情况下弱值的物理意义，并对已有的基于光子自旋霍尔效应的弱测量理论进行相应修正，最后针对不同类型的弱值与自旋分裂设计实验来进行全面验证。研究结果不仅将进一步提高光子自旋霍尔效应在精密测量中的探测精度，而且将为发展基于自旋的新型纳米光子学器件提理论指导和实验依据。

本项目从光子自旋霍尔效应、弱值的基本理论出发，研究了当系统被观测量与测量仪器之间的耦合程度较强或前、后选择态接近正交两种特殊情况下的弱测量修正理论。研究结果表明通过合适的理论修正能够得到完整且合理的弱值表达式以及光子自旋霍尔效应放大后横移表达式，研究小组通过数值模拟和实验等手段验证了其正确性，其成果具有很好的理论意义与实用价值。本项目严格按照研究计划执行，并在规定的期限内较好地完成了科研任务。基于该项目的研究成果，已在国际权威期刊上发表SCI论文8篇，其中Physical Review B 1篇，Optics Letters 1篇，Applied Physics Letters 1篇，Optics Express 2篇。项目负责人多次参加学术会议，并培养了硕士生4名。