Orbital angular momentum (OAM), characterized by a topological charge ℓ (ℓ integer), serves as a promising vehicle for carrying quantum information. Generating a nonclassical field involving two or more OAM modes can largely enhance the data-carrying capacity of quantum information processing. In this Letter, we present the implementation of a four-wave mixing (FWM) process, featuring a pump beam of a coherent OAM superposition mode and a probe beam of a single OAM mode. We generate twin beams encompassing multiple OAM modes and illustrate their quantum correlation when the pump beam assumes different coherent OAM superposition modes. Furthermore, we analyze the OAM mode components in each output field to deepen our understanding of the nonlinear interaction among different OAM modes. The obtained results show the rich structure of the nonlinear interaction of OAM modes in the FWM process and provide a perspective to study quantum information protocols.

中文翻译：

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轨道角动量叠加模式泵浦复杂四波混频过程实验演示

轨道角动量（OAM）以拓扑电荷ℓ（ℓ整数）为特征，是一种很有前途的承载量子信息的载体。生成涉及两种或多种OAM模式的非经典场可以大大增强量子信息处理的数据承载能力。在这封信中，我们介绍了四波混频（FWM）过程的实现，其特点是相干 OAM 叠加模式的泵浦光束和单 OAM 模式的探测光束。我们生成包含多个 OAM 模式的双光束，并说明当泵浦光束呈现不同相干 OAM 叠加模式时它们的量子相关性。此外，我们分析了每个输出场中的 OAM 模式分量，以加深我们对不同 OAM 模式之间非线性相互作用的理解。所得结果展示了FWM过程中OAM模式非线性相互作用的丰富结构，为研究量子信息协议提供了视角。