中山大学冯珑珑团队近日研究了光学狄拉克理论中的诱导Berry连接和光子自旋霍尔效应。相关论文于2025年7月15日发表在《物理评论A》杂志上。

在光学狄拉克理论的框架内，研究组提出了自旋-轨道相互作用和光子自旋和轨道霍尔效应的场理论模型。他们的方法将光沿着螺旋路径的传播重新表述为在基于光线的曲线坐标系中求解麦克斯韦方程。该系统可以被解释为介电张量中具有反对称元素的自旋简并介质，对应于以旋转偶极子矢量为特征的自旋-1激励模式。

研究组证明，在先导阶，得到的有效哈密顿量等效于均匀旋转框架中的麦克斯韦理论，同时包含自旋-旋转和轨道-旋转耦合。这种旋转源于螺旋路径的扭转，表现为光子的外在轨道角动量（EOAM）。值得注意的是，光子的自旋角动量和它的固有轨道角动量共同贡献了几何相位。在海森堡的图像中，自旋和轨道霍尔效应自然地出现在射线方程中的相互作用项中。此外，研究组发现倏逝波的横向自旋与EOAM耦合，表明椭圆偏振光的几何相位与圆偏振光的几何相位不同。这种区别强调了自旋轨道耦合在改变相积累中的作用。

附：英文原文

Title: Induced Berry connection and photonic spin Hall effect in optical Dirac theory

Author: Lili Yang, Longlong Feng

Issue&Volume: 2025/07/15

Abstract: Within the framework of optical Dirac theory, we present a field-theoretical model of spin-orbit interaction and photonic spin and orbital Hall effects. Our approach reformulates light propagation along helical paths as solving the Maxwell equations in a ray-based curvilinear coordinate system. This system can alternatively be interpreted as a spin-degenerate medium with antisymmetric elements in the dielectric tensor, corresponding to the spin-1 excitation mode characterized by a rotational dipole vector. We show that, at leading order, the resulting effective Hamiltonian is equivalent to the Maxwell theory in a uniformly rotating frame, incorporating both spin-rotation and orbit-rotation coupling. This rotation arises from the torsion of helical paths, manifesting as extrinsic orbital angular momentum (EOAM) of photons. Notably, the spin angular momentum of the photon and its intrinsic orbital angular momentum contribute jointly to the geometric phase. In the Heisenberg picture, the spin and orbital Hall effects naturally emerge from interaction terms in the ray equations. Furthermore, we find that the transverse spin of evanescent waves couples with EOAM, revealing that the geometric phase of elliptically polarized light differs from that of circularly polarized light. This distinction underscores the role of spin-orbit coupling in modifying phase accumulation.

DOI: 10.1103/b3ls-krx1

Source: https://journals.aps.org/pra/abstract/10.1103/b3ls-krx1