Measurement of Ion Motion Caused by Laser-Induced Stray Charges on Microfabricated Ion Trap Chip Surfaces

Abstract

© 2021 IEEE.The stray charges induced on ion trap surfaces can push trapped ions away from a pseudopotential null point. This can cause the micromotion of the trapped ions that in turn results in ion heating. One of the causes of stray charges is laser scattering on dielectric surfaces. The amount of laser-induced stray charges can be related to the area of the dielectric surface exposed to the ions. In this paper, stray charges are intentionally created at various dielectric surfaces on a microfabricated ion trap chip using a laser, and the resulting ion motion is measured. The ion movements are estimated by comparing ion positions before and after laser irradiation. When the laser irradiates a dielectric surface with an area of approximately 1,750 μm2 exposed to the ion, the ion moves approximately -4.8 μm in the axial direction. When the laser irradiates another dielectric surface with an area of approximately 140 μm2 exposed to the ion, the ion moves approximately -0.6 μm. The ratio between the ion movements corresponds to the ratio between the areas of each dielectric surface directly exposed to the ion normalized to the distance between the ion and the laser-induced stray charges. The results indicate the importance of reducing the area of dielectric surfaces that are directly in the line of laser paths.