High-frequency dynamics of the liquid and solid phases of electrons on helium

The Coulomb liquid and solid states of electrons floating above the surface of superfluid helium exhibit non-trivial spatial structure and high-frequency temporal dynamics. This is particularly true of the collective interaction between the electronic Wigner solid state and the bosonic field of capillary waves (ripplons) on the helium surface. Here we present high-frequency transport measurements of microchannel confined electrons on helium to probe the interaction between the electron system and the thermal ripplonic bath. The measurements are carried out over a wide range of frequency from 0.1-170 MHz via capacitively coupled lock-in techniques. At frequencies above ~10MHz a significant parasitic background contribution to the signal is present and we describe a compensation circuit used to cancel this signal enabling us to observe the high-frequency resonant emission of ripplons by the electron system.