Surface-science studies of electric-field noise from ion-trap electrodes

Heating of the motional modes of ions in a rf Paul trap is a major obstacle to trapped-ion quantum information processing (QIP). It is caused by electric-field noise from the surface of the trap electrodes, which couples to the ions’ net charge. A better understanding of the physical origin of this surface noise will help to mitigate this heating in trapped-ion QIP applications. To aid in tackling this problem, our group has constructed a one-of-a-kind trapped-ion surface probe, where the ion is used to measure noise from the surfaces of nearby samples positioned into close proximity. This novel surface probe is operated in situ with traditional surface science tools, namely SPM, XPS, and SPA-LEED, where the sample is transferred from instrument to instrument in vacuum. Various treatments to the sample surfaces will elucidate possible origins of the noise. For example, in situ cleaning of the trap electrodes by Ar-ion bombardment reduces this noise by 1 – 2 orders of magnitude. In this talk, I will describe the composition and surface-potential landscape of typical as-fabricated and treated ion-trap electrodes and show results where we have demonstrated the efficacy to use trapped ions as a probe to nearby surfaces.