Investigating the Trapping Mechanisms of Electrons on Solid Neon: The Effect of Trench Roughness

The motional states of electrons trapped on a solid neon substrate have the potential to become a highly coherent qubit platform; however, the detailed trapping mechanism that sets the motional energy states remains unknown. Recent studies have shown that the surface roughness of the neon film can lead to localized electron states with energy levels in the GHz frequency range. These studies typically employ traps fabricated on silicon substrates using reactive ion etching, which results in a rough silicon surface in the trench region. We compare the electron trapping capabilities of such etched niobium-on-silicon devices with specially engineered devices that feature a much smoother trench region. Our work provides experimental insights into the physical nature of trapped electrons on solid neon.