We report on low-temperature noise measurements of a single electron transistor (SET) immersed in superfluid 4He. The device acts as a charge sensitive electrometer able to detect the fluctuations of charged defects in close proximity to the SET. In particular, we measure telegraph switching of the electric current through the device originating from a strongly coupled individual two-level fluctuator. By embedding the device in a superfluid helium immersion cell we are able to systematically control the thermalizing environment surrounding the SET and investigate the effect of the superfluid on the SET noise performance. We find that the presence of superfluid 4He can strongly suppress the switching rate of the defect by cooling the surrounding phonon bath.
@article{arxiv.2010.06675,
title = {Noise performance & thermalization of single electron transistors using quantum fluids},
author = {N. R. Beysengulov and J. R. Lane and J. M. Kitzman and K. Nasyedkin and D. G. Rees and J. Pollanen},
journal= {arXiv preprint arXiv:2010.06675},
year = {2021}
}