We demonstrate full charge control, narrow optical linewidths, and optical spin pumping on single self-assembled InGaAs quantum dots embedded in a 162.5nm thin diode structure. The quantum dots are just 88nm from the top GaAs surface. We design and realize a p-i-n-i-n diode that allows single-electron charging of the quantum dots at close-to-zero applied bias. In operation, the current flow through the device is extremely small resulting in low noise. In resonance fluorescence, we measure optical linewidths below 2μeV, just a factor of two above the transform limit. Clear optical spin pumping is observed in a magnetic field of 0.5T in the Faraday geometry. We present this design as ideal for securing the advantages of self-assembled quantum dots -- highly coherent single photon generation, ultra-fast optical spin manipulation -- in the thin diodes required in quantum nano-photonics and nano-phononics applications.
@article{arxiv.1708.00520,
title = {Narrow optical linewidths and spin pumping on charge-tunable, close-to-surface self-assembled quantum dots in an ultra-thin diode},
author = {Matthias C. Löbl and Immo Söllner and Alisa Javadi and Tommaso Pregnolato and Rüdiger Schott and Leonardo Midolo and Andreas V. Kuhlmann and Søren Stobbe and Andreas D. Wieck and Peter Lodahl and Arne Ludwig and Richard J. Warburton},
journal= {arXiv preprint arXiv:1708.00520},
year = {2020}
}