Zhu Kuntuo, Lin Zaisheng, Yin Liuguo, Wang Chuan, Long Guilu
Opt Express. 2020 Dec 7;28(25):38366-38375. doi: 10.1364/OE.408934.
In this paper, we describe the study of the faithful propagation of entangled orbital angular momentum states of light under atmospheric turbulence. The spatial mode is encoded in the Ince-Gauss modes that constitute a complete family of exact and orthogonal solutions of the paraxial wave equation in an elliptic coordinate system. Adaptive optics is employed to protect the entanglement from degradation, in which the threshold of turbulence strength could be enhanced for a reliable entanglement distribution. We find that the evolution of entanglements relies on ellipticity and shows the opposite trend when adopting adaptive optics. The turbulence strengths, at which the concurrences of various entangled states become zero, are different without adaptive optics but almost the same with adaptive optics. The trace of the density matrix is independent of the different ellipticity with or without adaptive optics. We believe that this investigation is useful for long-distance quantum communications and quantum networks using orbital angular momentum as information carriers.
在本文中，我们描述了对光的纠缠轨道角动量态在大气湍流下的忠实传播的研究。空间模式编码在因次 - 高斯模式中，这些模式构成了椭圆坐标系中傍轴波动方程的一族完整的精确且正交解。采用自适应光学来保护纠缠不致退化，通过这种方式可以提高湍流强度阈值以实现可靠的纠缠分布。我们发现纠缠的演化依赖于椭圆率，并且在采用自适应光学时呈现出相反的趋势。在没有自适应光学的情况下，各种纠缠态的并发度变为零的湍流强度不同，但在有自适应光学时几乎相同。密度矩阵的迹与有无自适应光学时的不同椭圆率无关。我们相信这项研究对于使用轨道角动量作为信息载体的长距离量子通信和量子网络是有用的。
