An analytical approach to symmetry breaking in multipole RF-traps

Marylise Marchenay (1) , Jofre Pedregosa-Gutierrez (1) , Martina Knoop (1) , Marie Houssin (1) , Caroline Champenois (1)

1 PIIM - Physique des interactions ioniques et moléculaires

Radio-frequency linear multipole traps have been shown to be very sensitive to mis-positioning of their electrodes, which results in a symmetry breaking and leads to extra local minima in the trapping potential [1] disturbing the operation of the trap. In this work, we analytically describe the RF-potential of a realistic octupole trap by including lower order terms to the well-established equation for a perfectly symmetric octupole trap. We describe the geometry by a combination of identified defects, characterised by simple analytical expressions. A complete equation is proposed for a trap with any electrode deviation relying on a combination of the simple cases where the defects are taken individually. Our approach is validated by comparison between analytical and numerical results for defect sizes up to 4% of the trap radius. As described in [2], an independent fine-tuning of the amplitude of the RF voltage applied on each electrode can be used to mitigate the geometrical defects of a realistic trap. In a different way than in [2], the knowledge of an analytical equation for the potential allows to design the set of RF-voltages required for this compensation, based on the experimental measurement of the ion position in the trap, without information concerning the exact position of each electrode, and with a small number of iterations. The requirements, performances and limitations of this protocol are discussed via comparison of numerical simulations and analytical results.

Mots clés: radio-frequency traps; multipole linear trap; trap technology

Domaines: Physique Quantique [quant-ph]; Physique [physics]

Marylise Marchenay, Jofre Pedregosa-Gutierrez, Martina Knoop, Marie Houssin, Caroline Champenois. An analytical approach to symmetry breaking in multipole RF-traps. Quantum Science and Technology, In press, special issue, 6 (2), pp.024016. ⟨10.1088/2058-9565/abeaf6⟩. ⟨hal-03066318v2⟩