A low power photoemission source for electrons on liquid helium

TL;DR

This paper presents a low power, pulsed photoemission source for electrons on liquid helium, enabling reliable electron generation without heating, which is crucial for quantum computing research.

Contribution

It introduces a compact, low power pulsed light source for photoemission on helium, avoiding heating issues of previous high power systems.

Findings

Collected about 5,000 electrons per pulse on 1 cm^2 surface

Electrons emitted over or tunnel through the helium barrier

No trapping or bubble formation observed

Abstract

Electrons on the surface of liquid helium are a widely studied system that may also provide a promising method to implement a quantum computer. One experimental challenge in these studies is to generate electrons on the helium surface in a reliable manner without heating the cryo-system. An electron source relying on photoemission from a zinc film has been previously described using a high power continuous light source that heated the low temperature system. This work has been reproduced more compactly by using a low power pulsed lamp that avoids any heating. About 5e3 electrons are collected on 1 cm^2 of helium surface for every pulse of light. A time-resolved experiment suggests that electrons are either emitted over or tunnel through the 1eV barrier formed by the thin superfluid helium film on the zinc surface. No evidence of trapping or bubble formation is seen.