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arXiv · 2304.14245

Discrete frequency-bin entanglement generation via cascaded second-order nonlinear processes in Sagnac interferometer

Jiarui Li·Chenzhi Yuan·Si Shen·Zichang Zhang·Ruiming Zhang·Hao Li·You Wang·Guangwei Deng·Lixing You·Zhen Wang·Haizhi Song·Yunru Fan·Guangcan Guo·Qiang Zhou
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Abstract

Discrete frequency-bin entanglement is an essential resource for applications in quantum information processing. In this Letter, we propose and demonstrate a scheme to generate discrete frequency-bin entanglement with a single piece of periodically poled lithium niobate waveguide in a modified Sagnac interferometer. Correlated two-photon states in both directions of the Sagnac interferometer are generated through cascaded second-order optical nonlinear processes. A relative phase difference between the two states is introduced by changing the polarization state of pump light, thus manipulating the two-photon state at the output of the Sagnac interferometer. The generated two-photon state is sent into a fiber polarization splitter, then a pure discrete frequency-bin entangled two-photon state is obtained by setting the pump light. The frequency entanglement property is measured by a spatial quantum beating with a visibility of $96.0 \pm 6.1\%$. The density matrix is further obtained with a fidelity of $98.0 \pm 3.0\%$ to the ideal state. Our demonstration provides a promising method for the generation of pure discrete frequency-bin entanglement at telecom band, which is desired in quantum photonics.

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Jiarui Li, Chenzhi Yuan, Si Shen, Zichang Zhang, Ruiming Zhang, Hao Li, You Wang, Guangwei Deng, Lixing You, Zhen Wang, Haizhi Song, Yunru Fan, Guangcan Guo, Qiang Zhou. 2023-04-27. Discrete frequency-bin entanglement generation via cascaded second-order nonlinear processes in Sagnac interferometer. https://doi.org/10.1364/ol.489656

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