Motivated by the success of group IV colour centres in nanodiamonds (NDs) for hybrid technology requiring a single photon source, we study single germanium-vacancy (GeV−) centres in NDs at room temperature with size rangingfrom 10 to 50 nm and with remarkable spectral properties. We characterize their zero-phonon line (ZPL), study their internal population dynamics and compare their emission properties in the framework of a three level model with intensity dependent de-shelving. Furthermore, we characterize their lifetime, polarization and brightness. We find amaximum photon emission count rate of 1.6 MHz at saturation. We also report a polarization visibility of 92% from the fluorescence light, which potentially makes GeV− centres good candidates for quantum key distribution (QKD)requiring polarized single photons. We show that the GeV− in NDs presented in this work have a comparable spectral stability compared to their bulk counterpart which is needed for future applications using NDs.
@article{arxiv.2010.15475,
title = {Single germanium vacancy centres in nanodiamonds with bulk-like spectral stability},
author = {Mackrine Nahra and Daniel Alshamaa and Regis Deturche and Valery Davydov and Ludmila Kulikova and Viatcheslav Agafonov and Christophe Couteau},
journal= {arXiv preprint arXiv:2010.15475},
year = {2024}
}