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arXiv · 2103.06686

Topologically protected valley-dependent quantum photonic circuits

Yang Chen·Xin-Tao He·Yu-Jie Cheng·Hao-Yang Qiu·Lan-Tian Feng·Ming Zhang·Dao-Xin Dai·Guang-Can Guo·Jian-Wen Dong·Xi-Feng Ren
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Abstract

Topological photonics has been introduced as a powerful platform for integrated optics, since it can deal with robust light transport, and be further extended to the quantum world. Strikingly, valley-contrasting physics in topological photonic structures contributes to valley-related edge states, their unidirectional coupling, and even valley-dependent wave-division in topological junctions. Here, we design and fabricate nanophotonic topological harpoon-shaped beam splitters (HSBSs) based on $120$-deg-bending interfaces and demonstrate the first on-chip valley-dependent quantum information process. Two-photon quantum interference, namely, HongOu-Mandel (HOM) interference with a high visibility of $0.956 \pm 0.006$, is realized with our 50/50 HSBS, which is constructed by two topologically distinct domain walls. Cascading this kind of HSBS together, we also demonstrate a simple quantum photonic circuit and generation of a path-entangled state. Our work shows that the photonic valley state can be used in quantum information processing, and it is possible to realize more complex quantum circuits with valley-dependent photonic topological insulators, which provides a novel method for on-chip quantum information processing.

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Yang Chen, Xin-Tao He, Yu-Jie Cheng, Hao-Yang Qiu, Lan-Tian Feng, Ming Zhang, Dao-Xin Dai, Guang-Can Guo, Jian-Wen Dong, Xi-Feng Ren. 2021-03-11. Topologically protected valley-dependent quantum photonic circuits. https://doi.org/10.1103/physrevlett.126.230503

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