Noise performance & thermalization of single electron transistors using quantum fluids

TL;DR

This study investigates how immersing a single electron transistor in superfluid helium affects its noise characteristics, demonstrating that superfluid $^4$He can significantly reduce defect switching rates by cooling the environment.

Contribution

It provides the first systematic analysis of superfluid helium's impact on SET noise performance and defect dynamics at low temperatures.

Findings

Superfluid helium suppresses defect switching rates.

The environment's thermalization influences noise performance.

Superfluid $^4$He enhances device stability by cooling phonon baths.

Abstract

We report on low-temperature noise measurements of a single electron transistor (SET) immersed in superfluid $^4$He. 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 $^4$He can strongly suppress the switching rate of the defect by cooling the surrounding phonon bath.