Surface traps for freely rotating ion ring crystals

Rings of trapped ions are an attractive system to study quantum-many body dynamics with closed boundary conditions as well as symmetry breaking. One of the biggest challenges towards such experiments is to sufficiently suppress rotational imperfections of the trapping potential and to allow for instance freely rotating ring structures. We show how to overcome this challenge with a surface trap design and perform numerical calculations to analyze the consequences of various imperfections in detail. We conclude that trap electrode imperfections, external stray electric fields, and local charging of the trap electrodes can be controlled sufficiently well to allow ion rings to rotate freely even near their rotational ground state.