Many-electron system on helium and the color center spectroscopy

TL;DR

This paper investigates how magnetic fields influence the absorption spectrum of electrons on helium surfaces, revealing insights into many-electron dynamics and enabling tests of color center theories in a controllable system.

Contribution

It demonstrates the effect of magnetic fields on electron absorption spectra by showing the admixing of out-of-plane motion with in-plane quantum dynamics in electron liquids and Wigner crystals.

Findings

Magnetic fields alter the absorption spectrum of electrons on helium.

The spectrum reflects the many-electron quantum dynamics.

The system allows testing of color center theories with controllable coupling.

Abstract

Electrons on the helium surface display sharp resonant absorption lines related to the transitions between the subbands of quantized motion transverse to the surface. A magnetic field parallel to the surface strongly affects the absorption spectrum. We show that the effect comes from admixing the out-of-plane motion to the in-plane quantum dynamics of the strongly correlated electron liquid or a Wigner crystal. This is similar to the admixing electron transitions in color centers to phonons. The spectrum permits a direct characterization of the many-electron dynamics and also enables testing the theory of color centers in a system with a controllable coupling.