Color centers in hexagonal boron nitride have shown enormous promise as single-photon sources, but a clear understanding of electron-phonon interaction dynamics is critical to their development for quantum communications or quantum simulations. We demonstrate photon antibunching in the filtered auto- and cross-correlations glm(2)(τ) between zero-, one- and two-phonon replicas of defect luminescence. Moreover, we combine autocorrelation measurements with a violation of the Cauchy-Schwarz inequality in the filtered cross-correlation measurements to distinguish a low quantum-efficiency defect from phonon replicas of a bright defect. With no background correction, we observe single photon purity of g(2)(0)=0.20 in a phonon replica and cross-spectral correlations of glm(2)(0)=0.18 between a phonon replica and the zero phonon line. These results illustrate a coherent interface between visible photons and mid-infrared phonons and provide a clear path toward control of photon-phonon entanglement in 2D materials.
@article{arxiv.1808.07119,
title = {Phonon-induced multi-color correlations in hBN single-photon emitters},
author = {Matthew Feldman and Alex Puretzky and Lucas Lindsay and Ethan Tucker and Dayrl Briggs and Philip Evans and Richard Haglund and Benjamin Lawrie},
journal= {arXiv preprint arXiv:1808.07119},
year = {2019}
}