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arXiv · 2408.06751

Polarization entanglement enabled by orthogonally stacked van der Waals NbOCl2 crystals

Qiangbing Guo·Yun-Kun Wu·Di Zhang·Qiuhong Zhang·Guang-Can Guo·Andrea Alù·Xi-Feng Ren·Cheng-Wei Qiu
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Abstract

Polarization entanglement holds significant importance for photonic quantum technologies. Recently emerging subwavelength nonlinear quantum light sources, e.g., GaP and LiNbO3 thin films, benefiting from the relaxed phase-matching constraints and volume confinement, has shown intriguing properties, such as high-dimensional hyperentanglement and robust entanglement anti-degradation. Van der Waals (vdW) NbOCl2 crystal, renowned for its superior optical nonlinearities, has emerged as one of ideal candidates for ultrathin quantum light sources [Nature 613, 53 (2023)]. However, polarization-entanglement is inaccessible in NbOCl2 crystal due to its unfavorable nonlinear susceptibility tensor. Here, by leveraging the twist-stacking degree of freedom inherently in vdW systems, we showcase the preparation of tunable polarization entanglement and quantum Bell states. Our work not only provides a new and tunable polarization-entangled vdW photon-pair source, but also introduces a new knob in engineering the entanglement state of quantum light at the nanoscale.

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Qiangbing Guo, Yun-Kun Wu, Di Zhang, Qiuhong Zhang, Guang-Can Guo, Andrea Alù, Xi-Feng Ren, Cheng-Wei Qiu. 2024-08-13. Polarization entanglement enabled by orthogonally stacked van der Waals NbOCl2 crystals. https://arxiv.org/abs/2408.06751

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