# Symmetry breaking in linear multipole traps

## TL;DR

This paper investigates symmetry breaking in a macroscopic octupole ion trap, combining experimental observations with numerical simulations to understand and control local potential minima affecting ion trapping.

## Contribution

It provides the first detailed experimental analysis of symmetry breaking in octupole traps and models the formation of local potential minima for improved trap control.

## Key findings

- Symmetry breaking leads to additional local potential minima.
- The position and depth of minima depend on rod displacement.
- Control over potential minima can improve trap stability.

## Abstract

Radiofrequency multipole traps have been used for some decades in cold collision experiments, and are gaining interest for precision spectroscopy due to their low mi-cromotion contribution, and the predicted unusual cold-ion structures. However, the experimental realisation is not yet fully controlled, and open questions in the operation of these devices remain. We present experimental observations of symmetry breaking of the trapping potential in a macroscopic octupole trap with laser-cooled ions. Numerical simulations have been performed in order to explain the appearance of additional local potential minima, and be able to control them in a next step. We characterize these additional potential minima, in particular with respect to their position, their potential depth and their probability of population as a function of the radial and angular displacement of the trapping rods.