Quantitative evaluation and regulation of cold-ion system intrinsic micromotion by numerical simulation

Abstract The intrinsic micromotion of radio-frequency (RF) trapped three-dimensional (3D) cold ion systems plays an important role in the trapping, cooling, and manipulation of ions, and exhibits significantly different characteristics, compared to those of single-ion or chain-ion systems. In this study, the kinetic mechanism of the intrinsic micromotion of a 3D ion system is systematically studied, the 3D correlative coupling features between the intrinsic micromotion and secular motion are quantitatively assessed, and the transient evolution characteristics of the intrinsic micromotion are identified. In addition, the performances and application ranges of the two regulation methods, iso-q (stability trapping parameter) and iso-frequency, in inhibiting the intrinsic micromotion of 3D-ion crystals are compared, and a method for inhibiting intrinsic micromotion, while maintaining the spatial configuration of the 3D ion system is presented. The obtained results provide a basis for resolving the physical problems of 3D ion systems, such as long-term trapping without ion loss under a low heating rate, precision coherent manipulation, motion-effect inhibition, high-efficiency laser cooling, and sympathetic cooling. Furthermore, they facilitate the control of cold chemical reactions, coherence delay of the quantum states, and spectrum measurements approaching the theoretical precision limit of 3D ion systems.