Compact generation scheme of path–frequency hyperentangled photons using 2D periodical nonlinear photonic crystal

• Published in: Chinese physics B Vol. 32; no. 12; pp. 120307 - 120313
• Main Authors: Chen, Yang-He, Ji, Bo, Li, Nian-Qin, Jiang, Zhen, Li, Wei, Li, Yu-Dong, Feng, Liang-Sen, Wu, Teng-Fei, He, Guang-Qiang
• Format: Journal Article
• Language: English
• Published: Chinese Physical Society and IOP Publishing Ltd 01.12.2023
• Subjects: hyperentanglement; nonlinear photonic crystal; quasi-phase-matching
• ISSN: 1674-1056; 2058-3834
• DOI: 10.1088/1674-1056/ad0625

Hyperentanglement is a promising resource for achieving high capacity quantum communication. Here, we propose a compact scheme for the generation of path–frequency hyperentangled photon pairs via spontaneous parametric down-conversion (SPDC) processes, where six different paths and two different frequencies are covered. A two-dimensional periodical χ (2) nonlinear photonic crystal (NPC) is designed to satisfy type-I quasi-phase-matching conditions in the plane perpendicular to the incident pump beam, and a perfect phase match is achieved along the pump beam’s direction to ensure high conversion efficiency, with theoretically estimated photon flux up to 2.068 × 10 5 pairs⋅s −1 ⋅mm −2 . We theoretically calculate the joint-spectral amplitude (JSA) of the generated photon pair and perform Schmidt decomposition on it, where the resulting entropy S of entanglement and effective Schmidt rank K reach 3.2789 and 6.4675, respectively. Our hyperentangled photon source scheme could provide new avenues for high-dimensional quantum communication and high-speed quantum information processing.