A pair of coupled dots with one electron in each dot can provide improvements in spin coherence, particularly at an electrical bias called the sweet spot, but few measurements have been performed on self-assembled dots in this regime. Here, we directly measure the T2∗ coherence time of the singlet-triplet states in this system as a function of bias and magnetic field, obtaining a maximum T2∗ of 60 ns, more than an order of magnitude higher than an electron spin in a single quantum dot. Our results uncover two main dephasing mechanisms: electrical noise away from the sweet spot, and a magnetic field dependent interaction with nuclear spins due to a difference in g-factors.
@article{arxiv.2202.08256,
title = {Enhanced spin coherence at the sweet spot of a self-assembled quantum dot molecule},
author = {Kha X. Tran and Allan S. Bracker and Michael K. Yates and Joel Q. Grim and Samuel G. Carter},
journal= {arXiv preprint arXiv:2202.08256},
year = {2022}
}