Subnatural-linewidth single photons are of vital importance in quantum optics and quantum information science. According to previous research, it appears difficult to utilize resonance fluorescence to generate single photons with subnatural linewidth. Here we propose a universally applicable approach to generate fluorescent single photons with subnatural linewidth, which can be implemented based on Λ$\mathrm{\Lambda }$-shape and similar energy structures. Further, the general condition to obtain fluorescent single photons with subnatural linewidth is revealed. The single-photon linewidth can be easily manipulated over a broad range by external fields, which can be several orders of magnitude smaller than the natural linewidth. Our study can be easily implemented in various physical platforms with current experimental techniques and will significantly facilitate the research on the quantum nature of resonance fluorescence and the technologies in quantum information science.

中文翻译：

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次自然线宽荧光单光子

次自然线宽单光子在量子光学和量子信息科学中至关重要。根据之前的研究，利用共振荧光产生具有非自然线宽的单光子似乎很困难。在这里，我们提出了一种普遍适用的方法来生成具有亚自然线宽的荧光单光子，该方法可以基于Λ$\mathrm{\Lambda }$形状和类似的能量结构来实现。此外，还揭示了获得具有亚自​​然线宽的荧光单光子的一般条件。单光子线宽可以很容易地通过外部场在很宽的范围内操纵，该线宽可以比自然线宽小几个数量级。我们的研究可以通过现有的实验技术轻松地在各种物理平台上实现，并将极大地促进共振荧光的量子性质和量子信息科学技术的研究。