The phenomenon of entanglement is the basis of quantum information and quantum communication processes. Entangled systems with a large number of photons are of great interest at present because they provide a platform for streaming technologies based on photonics. In this paper we present a device which operates with four-photons and based on the Hong–Ou–Mandel interference. The presented device allows to maximize the degree of spatial entanglement and generate the highly entangled four-dimensional Bell states. Furthermore, the use of the interferometer in different regimes leads to fast interference fringes in the coincidence probability with period of oscillations twice smaller than the pump wavelength. We have a good agreement between theoretical simulations and experimental results.

中文翻译：

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通过四光子Hong-Ou-Mandel干涉进行空间纠缠和状态工程

纠缠现象是量子信息和量子通信过程的基础。具有大量光子的纠缠系统目前备受关注，因为它们为基于光子学的流技术提供了平台。在本文中，我们介绍了一种基于Hong-Ou-Mandel干扰的四光子器件。提出的装置允许最大化空间纠缠度并产生高度纠缠的四维贝尔状态。此外，在不同情况下使用干涉仪会导致重合条纹出现快速干涉条纹，其振荡周期比泵浦波长小两倍。我们在理论模拟和实验结果之间有很好的一致性。