An extensive investigation of low frequency noise in single electron transistors as a function of gain is presented. Comparing the output noise with gain for a large number of bias points, it is found that the noise is dominated by external charge noise. For low gains we find an additional noise contribution which is compared to a model including resistance fluctuations. We conclude that this excess noise is not only due to resistance fluctuations. For one sample, we find a record low minimum charge noise of qn = 9*10^-6 e/sqrt(Hz) in the superconducting state and qn = 9*10^-6 e/sqrt(Hz) in the normal state at a frequency of 4.4 kHz.
@article{arxiv.cond-mat/9806354,
title = {Gain Dependence of the Noise in the Single Electron Transistor},
author = {B. Starmark and Torsten Henning and A. N. Korotkov and T. Claeson and P. Delsing},
journal= {arXiv preprint arXiv:cond-mat/9806354},
year = {2016}
}