Parallel ion strings in linear multipole traps

TL;DR

This paper demonstrates how applying additional rf potentials to linear multipole traps creates field-free regions that enable stable confinement and manipulation of ion strings, which can be laser cooled to the Doppler limit and moved with minimal heating.

Contribution

It introduces a method to generate and control ion strings in rf field-free regions within linear multipole traps, enhancing ion manipulation capabilities.

Findings

Ion strings can be laser cooled to the Doppler limit in all directions.

Ion systems can be moved with limited heating after cooling.

The number and position of field nodes are tunable via applied voltages.

Abstract

Additional radio-frequency (rf) potentials applied to linear multipole traps create extra field nodes in the radial plane which allow one to confine single ions, or strings of ions, in totally rf field-free regions. The number of nodes depends on the order of the applied multipole potentials and their relative distance can be easily tuned by the amplitude variation of the applied voltages. Simulations using molecular dynamics show that strings of ions can be laser cooled down to the Doppler limit in all directions of space. Once cooled, organized systems can be moved with very limited heating, even if the cooling process is turned off.