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

doi:10.1038/s41467-024-54876-w

Polarization entanglement enabled by orthogonally stacked van der Waals NbOCl₂ crystals

Nat Commun. 2024 Dec 2;15(1):10461. doi: 10.1038/s41467-024-54876-w.

Authors

Qiangbing Guo^#^{1

2}, Yun-Kun Wu^#^{3

4

5}, Di Zhang^#^{6

7}, Qiuhong Zhang⁸, Guang-Can Guo^{3

4

5}, Andrea Alù^{6

9}, Xi-Feng Ren^{10

11

12}, Cheng-Wei Qiu^{13

14}

Affiliations

¹ Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore. qbguo90@hotmail.com.
² Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, Singapore. qbguo90@hotmail.com.
³ CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, China.
⁴ CAS Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, China.
⁵ Hefei National Laboratory, University of Science and Technology of China, Hefei, China.
⁶ Photonics Initiative, Advanced Science Research Center, City University of New York, New York, NY, USA.
⁷ The Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, School of Physics and TEDA Applied Physics Institute, Nankai University, Tianjin, China.
⁸ School of Chemistry and Materials Science, Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, Hangzhou, China.
⁹ Physics Program, Graduate Center, City University of New York, New York, NY, USA.
¹⁰ CAS Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, China. renxf@ustc.edu.cn.
¹¹ CAS Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, China. renxf@ustc.edu.cn.
¹² Hefei National Laboratory, University of Science and Technology of China, Hefei, China. renxf@ustc.edu.cn.
¹³ Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore. chengwei.qiu@nus.edu.sg.
¹⁴ Centre for Advanced 2D Materials and Graphene Research Centre, National University of Singapore, Singapore, Singapore. chengwei.qiu@nus.edu.sg.

^# Contributed equally.

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, have shown intriguing properties, such as high-dimensional hyperentanglement and robust entanglement anti-degradation. Van der Waals (vdW) NbOCl₂ crystal, with strong optical nonlinearities, has emerged as a potential candidate for ultrathin quantum light sources. However, polarization entanglement is inaccessible in the 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 polarization entanglement and quantum Bell states.

Abstract

Grants and funding