Trapping electrons in electrostatic traps over the surface of helium

TL;DR

This paper demonstrates the trapping of electrons over liquid helium-4 using electrostatic traps, enabling precise control and measurement of electron temperature and thermalization times, advancing quantum surface electron research.

Contribution

It introduces a method to trap and measure multiple electrons over helium surface with high repeatability, providing new insights into electron dynamics at cryogenic surfaces.

Findings

Electrons can be trapped in numbers up to ~30.

The effective electron temperature can be measured.

Thermalization times after heating are characterized.

Abstract

We have observed trapping of electrons in an electrostatic trap formed over the surface of liquid helium-4. These electrons are detected by a Single Electron Transistor located at the centre of the trap. We can trap any desired number of electrons between 1 and $\sim 30$. By repeatedly ($\sim 10^3-10^4$ times) putting a single electron into the trap and lowering the electrostatic barrier of the trap, we can measure the effective temperature of the electron and the time of its thermalisation after heating up by incoherent radiation.