Mitigating electric field noise from Aluminum surfaces in close proximity to trapped ions*

Electrical noise from surfaces can be a challenge for quantum sensing and high-fidelity quantum information processing in atomic systems. In the trapped-ion context, the origin of this noise is unknown, but its characteristics appear dependent on the surface material. Previous work has demonstrated that the temperature dependence of the noise can be altered, and sometimes reduced, by energetic ion bombardment, or "ion milling" of trapping electrodes. The effectiveness of ex-situ ion milling in removing oxides and the subsequent effect on noise has been studied on Nb and Au. Here, we present temperature dependence of noise measurements using individual ions trapped near electrodes made from Al, a widely-used microelectronics material, before and after repeated rounds of ion milling; we also present measurements of the material removal rate of the milling treatments. These results demonstrate both noise reduction and variation in the effect of milling across various materials, suggesting a need to investigate the effect of milling on a material-by-material basis.