Coulomb crystallization of sympathetically cooled highly charged ions

Lijun Du, Y.S. Meng, Jinshu Lu +3 more

S. Schmidt, T. Murböck, Zoran Andelkovic +5 more

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.

Guin-Dar Lin, L.-M. Duan

Stephan Schiller, Bernhard Roth

A. Douillet, B. Wirtschafter, J.-P. Likforman +8 more

We study large multispecies Coulomb crystals in the case of a heavy coolant (88Sr+) and a light cooled species (9Be+), extending previously reported mass ratios [1]. This system has an interest for future experiments on highly charged ions [2] and on antimatter sympathetic cooling [3].[1] B. Roth et al., Phys. Rev. A, 75 023402 (2007).[2] L. Schmoger et al., Science, 347 1233 (2015).[3] P. Perez and Y. Sacquin, Classical and Quantum Gravity, 29 (2012).

Bernhard Roth, U. Fröhlich, Stephan Schiller

We have generated Coulomb crystals of ultracold $^{4}\mathrm{H}\mathrm{e}^{+}$ ions in a linear radio-frequency trap, by sympathetic cooling via laser-cooled $^{9}\mathrm{B}\mathrm{e}^{+}$. Stable crystals containing up to $150$ localized ${\mathrm{H}\mathrm{e}}^{+}$ ions at $\ensuremath{\sim}20\text{ }\text{ }\mathrm{m}\mathrm{K}$ were obtained. Ensembles or single ultracold ${\mathrm{H}\mathrm{e}}^{+}$ ions open up interesting perspectives for performing precision tests of QED and measurements of nuclear radii. This Letter also indicates the feasibility of cooling and crystallizing highly charged atomic ions using $^{9}\mathrm{B}\mathrm{e}^{+}$ as coolant.