Ultrathin quantum light source enabled by a nonlinear van der Waals crystal with vanishing interlayer-electronic-coupling
Abstract
Interlayer electronic coupling in two-dimensional (2D) materials enables tunable and emergent properties by stacking engineering. However, it also brings significant evolution of electronic structures and attenuation of excitonic effects in 2D semiconductors as exemplified by quickly degrading excitonic photoluminescence and optical nonlinearities in transition metal dichalcogenides when monolayers are stacked into van der Waals structures. Here we report a novel van der Waals crystal, niobium oxide dichloride, featuring a vanishing interlayer electronic coupling and scalable second harmonic generation intensity of up to three orders higher than that of exciton-resonant monolayer WS2. Importantly, the strong second-order nonlinearity enables correlated parametric photon pair generation, via a spontaneous parametric down-conversion (SPDC) process, in flakes as thin as ~46 nm. To our knowledge, this is the first SPDC source unambiguously demonstrated in 2D layered materials, and the thinnest SPDC source ever reported. Our work opens an avenue towards developing van der Waals material-based ultracompact on-chip SPDC sources, and high-performance photon modulators in both classical and quantum optical technologies.
Keywords
Cite
@article{arxiv.2202.03831,
title = {Ultrathin quantum light source enabled by a nonlinear van der Waals crystal with vanishing interlayer-electronic-coupling},
author = {Qiangbing Guo and Xiao-Zhuo Qi and Meng Gao and Sanlue Hu and Lishu Zhang and Wenju Zhou and Wenjie Zang and Xiaoxu Zhao and Junyong Wang and Bingmin Yan and Mingquan Xu and Yun-Kun Wu and Goki Eda and Zewen Xiao and Huiyang Gou and Yuan Ping Feng and Guang-Can Guo and Wu Zhou and Xi-Feng Ren and Cheng-Wei Qiu and Stephen J. Pennycook and Andrew T. S. Wee},
journal= {arXiv preprint arXiv:2202.03831},
year = {2023}
}