We report on the effects of a global top gate on low-frequency noise in Schottky gate-defined quantum point contacts (QPCs) and quantum dots (QDs) in a modulation-doped Si/SiGe heterostructure. For a relatively large top gate voltage, the QPC current shows frequent switching with 1/f2 Lorentzian type charge noise. As the top gate voltage is decreased, the QPC pinch-off voltage becomes less negative, and the 1/f2 noise becomes rapidly suppressed in a homogeneous background 1/f noise. We apply this top-gating technique to double QDs to stabilize the charge state for the electron number down to zero.
@article{arxiv.1304.0064,
title = {Characterization and Suppression of Low-frequency Noise in Si/SiGe Quantum Point Contacts and Quantum Dots},
author = {K. Takeda and T. Obata and Y. Fukuoka and W. M. Akhtar and J. Kamioka and T. Kodera and S. Oda and S. Tarucha},
journal= {arXiv preprint arXiv:1304.0064},
year = {2013}
}