The orbital angular momentum (OAM) carried by photons defines an infinitely dimensional discrete Hilbert space. With OAM modes, high-dimensional quantum states can be achieved for quantum communication and cryptography. Here we demonstrate a heralded single-photon source with a switchable OAM mode, which consists of a heralded single-photon source and an integrated OAM emitter as the mode converter. As the first step, the heralded single-photon source is based on the dispersion-shifted fiber. In this work, the OAM mode (quantized by topological charge $l$) carried by the heralded single photon (at fixed wavelength of 1555.75 nm) can be switched within the range of $l=3–7$ while the mode purity is more than 80%.

中文翻译：

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生成具有可切换轨道角动量模式的预兆单光子

光子携带的轨道角动量 (OAM) 定义了一个无限维离散希尔伯特空间。通过 OAM 模式，可以为量子通信和密码学实现高维量子态。在这里，我们展示了具有可切换 OAM 模式的预兆单光子源，它由预兆单光子源和作为模式转换器的集成 OAM 发射器组成。作为第一步，预告的单光子源基于色散位移光纤。在这项工作中，OAM 模式（由拓扑电荷量化$升$) 携带的单光子（固定波长为 1555.75 nm）可以在以下范围内切换 $升=3\mathrm{——}7$ 而模式纯度在80%以上。