Sensing Few Electrons Floating on Helium with High-Electron-Mobility Transistors

TL;DR

This paper demonstrates a cryogenic circuit using GaAs HEMTs for sensitive detection of few electrons on superfluid helium, achieving significantly improved signal-to-noise ratio over previous methods.

Contribution

The authors developed a low-noise cryogenic amplifier integrated with a CCD for electron transport on helium, offering a novel approach to electron sensing with enhanced performance.

Findings

Achieved a SNR of approximately 2 e/√Hz at 102 kHz.

Demonstrated an order of magnitude improvement over previous electron sensing techniques.

Provided an alternative method to high-frequency resonators for detecting few electrons.

Abstract

We report on low-frequency measurements of few electrons floating on superfluid helium using a bespoke cryogenic cascode amplifier circuit built with off-the-shelf GaAs High-Electron-Mobility Transistors (HEMTs). We integrate this circuit with a Charge-Coupled Device (CCD) to transport the electrons on helium and characterize its performance. We show that this circuit has a Signal-to-Noise ratio (SNR) of $\thicksim$ 2$\frac{e}{\sqrt{Hz}}$ at 102 kHz, an order of magnitude improvement from previous implementations and provides a compelling alternative to few electron sensing with high frequency resonators.