Electron spins in silicon have long coherence times and are a promising qubit platform. However, electric field noise in semiconductors poses a challenge for most single- and multi-qubit operations in quantum-dot spin qubits. Here, we investigate the dependence of low-frequency charge noise spectra on temperature and aluminum-oxide gate dielectric thickness in Si/SiGe quantum dots with overlapping gates. We find that charge noise increases with aluminum oxide thickness. We also find strong dot-to-dot variations in the temperature dependence of the noise magnitude and spectrum. These findings suggest that each quantum dot experiences noise caused by a distinct ensemble of two-level systems, each of which has a non-uniform distribution of thermal activation energies. Taken together, our results suggest that charge noise in Si/SiGe quantum dots originates at least in part from a non-uniform distribution of two-level systems near the surface of the semiconductor.
@article{arxiv.1907.07549,
title = {Low-frequency charge noise in Si/SiGe quantum dots},
author = {Elliot J. Connors and JJ Nelson and Haifeng Qiao and Lisa F. Edge and John M. Nichol},
journal= {arXiv preprint arXiv:1907.07549},
year = {2020}
}
Comments
v3: 12 pages, 6 figures. Includes corrections to figures F3, F4, and S2 as reported in Erratum to published version