Sympathetic cooling in two-species ion crystals in a Penning trap

Abstract

We have studied the formation and properties of two-species ion Coulomb crystals in the Penning trap of the SpecTrap experiment. These crystals have been formed by injection of admixture ions from an external source into a previously confined and laser-cooled cloud of magnesium ions. This kind of study, performed over a range of the admixture ions’ charge-to-mass ratios, indicates the conditions for their sympathetic cooling and the formation of two-species ion crystals. This mechanism allows efficient cooling of the admixed species such as highly charged ions which do not feature suitable laser-cooling transitions, and thus make them accessible to high-resolution laser spectroscopy.

Keywords:

• Laser cooling
• Penning trap
• ion Coulomb crystal
• laser spectroscopy

Acknowledgements

We acknowledge the many contributions of the late Danny Segal to this project over many years. We also acknowledge the work of all members of the SpecTrap collaboration. We thank Bernhard Maaß, Alexander Martin, Oliver Kaleja, Jörg Krämer, Tim Ratajczyk and Rodolfo Sanchez for their support in the execution of the experiment. S.S. and T.M. have contributed equally to this work. S.S. and T.M. acknowledge support from HGS-HIRe. The experiments have been performed within the framework of the HITRAP facility at GSI and FAIR, Darmstadt.

Notes

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the BMBF [contract number 05P15RDFAA]; HIC for FAIR within the LOEWE program by the federal state Hessen, the DFG [contract number BI 647/5-1]; the EPSRC [grant number EP/D068509/1].