Piezoacoustics for precision control of electrons floating on helium

TL;DR

This paper demonstrates the coupling of surface acoustic waves to electrons on helium, enabling precise electron transport and opening avenues for studying quantum and collective phenomena in this ultra-high mobility two-dimensional system.

Contribution

It introduces a novel method of using piezoelectric SAWs to control and investigate electrons on helium with high precision, advancing experimental capabilities in this unique quantum system.

Findings

Achieved ~0.01% precision in acoustoelectric electron transport.

Demonstrated SAWs as a tool for probing high-frequency dynamics of electron phases.

Enabled future experiments on quantized charge pumping and collective excitations.

Abstract

Piezoelectric surface acoustic waves (SAWs) are powerful for investigating and controlling elementary and collective excitations in condensed matter. In semiconductor two-dimensional electron systems SAWs have been used to reveal the spatial and temporal structure of electronic states, produce quantized charge pumping, and transfer quantum information. In contrast to semiconductors, electrons trapped above the surface of superfluid helium form an ultra-high mobility, two-dimensional electron system home to strongly-interacting Coulomb liquid and solid states, which exhibit non-trivial spatial structure and temporal dynamics prime for SAW-based experiments. Here we report on the coupling of electrons on helium to an evanescent piezoelectric SAW. We demonstrate precision acoustoelectric transport of as little as ~0.01% of the electrons, opening the door to future quantized charge pumping experiments. We also show SAWs are a route to investigating the high-frequency dynamical response, and relaxational processes, of collective excitations of the electronic liquid and solid phases of electrons on helium.