Entanglement is a major resource in advanced quantum technology, where it can enable secure exchange of information over large distances. Energy-time entanglement is particularly attractive for its beneficial robustness in fiber-based quantum communication and can be demonstrated in the Franson interferometer. We report on Franson-type interference from a resonantly driven biexciton cascade under continuous wave excitation. Our measurements yield a maximum visibility of (73 ± 2)% surpassing the limit of violation of Bell's inequality (70.7%) by more than one standard deviation. Despite being unable to satisfy a loophole free violation, our work demonstrates promising results concerning future works on such a system. Furthermore, our systematical studies on the impact of driving strength indicate that dephasing mechanisms and deviations from the cascaded emission have major impact on the degree of the measured energy-time entanglement.
@article{arxiv.2301.05697,
title = {Energy-time entanglement from a resonantly driven quantum dot three-level system},
author = {M. Hohn and K. Barkemeyer and M. von Helversen and L. Bremer and M. Gschrey and J. -H. Schulze and A. Strittmatter and A. Carmele and S. Rodt and S. Bounouar and S. Reitzenstein},
journal= {arXiv preprint arXiv:2301.05697},
year = {2023}
}