High-dimensional entanglement has demonstrated its potential for increasing channel capacity and resistance to noise in quantum information processing. However, distributing it is a challenging task, imposing severe restrictions on its application. Here we report the first distribution of three-dimensional orbital angular momentum (OAM) entanglement via a 1-km-long few-mode optical fiber. Using an actively stabilizing phase precompensation technique, we successfully transport one photon of a three-dimensional OAM entangled photon pair through the fiber. The distributed OAM entangled state still shows a fidelity up to 71% with respect to the three-dimensional maximally entangled state (MES). In addition, we certify that the high-dimensional quantum entanglement survives the transportation by violating a generalized Bell inequality, obtaining a violation of $ \sim 3 $ standard deviations from the classical limit with $ {I_3} = 2.12 \pm 0.04 $. The method we developed can be extended to a higher OAM dimension and larger distances in principle. Our results make a significant step towards future OAM-based high-dimensional long-distance quantum communication.

中文翻译：

---

1 km少模光纤上高维轨道角动量纠缠的分布

高维纠缠已显示出其在量子信息处理中增加通道容量和抗噪声能力的潜力。但是，分发它是一项艰巨的任务，对其应用施加了严格的限制。在这里，我们报告通过1公里长的少模光纤进行的三维轨道角动量（OAM）纠缠的第一个分布。使用主动稳定的相位预补偿技术，我们成功地将3维OAM纠缠光子对中的一个光子通过光纤传输。相对于三维最大纠缠态（MES），分布式OAM纠缠态仍显示出高达71％的保真度。另外，我们证明高维量子纠缠通过违反广义贝尔不等式而幸免于运输，$ \ sim 3 $与经典限制的标准偏差，其中$ {I_3} = 2.12 \ pm 0.04 $。我们开发的方法原则上可以扩展到更高的OAM尺寸和更大的距离。我们的结果向未来基于OAM的高维长距离量子通信迈出了重要一步。