title: Coulomb crystallization of highly charged ions.
abstract: Control over the motional degrees of freedom of atoms, ions, and molecules in a field-free environment enables unrivalled measurement accuracies but has yet to be applied to highly charged ions (HCIs), which are of particular interest to future atomic clock designs and searches for physics beyond the Standard Model. Here, we report on the Coulomb crystallization of HCIs (specifically (40)Ar(13+)) produced in an electron beam ion trap and retrapped in a cryogenic linear radiofrequency trap by means of sympathetic motional cooling through Coulomb interaction with a directly laser-cooled ensemble of Be(+) ions. We also demonstrate cooling of a single Ar(13+) ion by a single Be(+) ion-the prerequisite for quantum logic spectroscopy with a potential 10(-19) accuracy level. Achieving a seven-orders-of-magnitude decrease in HCI temperature starting at megakelvin down to the millikelvin range removes the major obstacle for HCI investigation with high-precision laser spectroscopy.
authors.affiliation: Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany. Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany.
authors.forename: L
authors.initials: L
authors.lastname: Schmöger
authors.affiliation: Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany. Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany.
authors.forename: O O
authors.initials: OO
authors.lastname: Versolato
authors.affiliation: Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany. Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Schwarz
authors.affiliation: Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany.
authors.forename: M
authors.initials: M
authors.lastname: Kohnen
authors.affiliation: Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Windberger
authors.affiliation: Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Piest
authors.affiliation: Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Feuchtenbeiner
authors.affiliation: Physique des Interactions Ioniques et Moléculaires, Aix-Marseille Université, 13397 Marseille, France.
authors.forename: J
authors.initials: J
authors.lastname: Pedregosa-Gutierrez
authors.affiliation: Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany.
authors.forename: T
authors.initials: T
authors.lastname: Leopold
authors.affiliation: Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany. Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany.
authors.forename: P
authors.initials: P
authors.lastname: Micke
authors.affiliation: Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark.
authors.forename: A K
authors.initials: AK
authors.lastname: Hansen
authors.affiliation: National Superconducting Cyclotron Laboratory (NSCL), Michigan State University, 640 S. Shaw Lane, East Lansing, MI 48824, USA.
authors.forename: T M
authors.initials: TM
authors.lastname: Baumann
authors.affiliation: Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark.
authors.forename: M
authors.initials: M
authors.lastname: Drewsen
authors.affiliation: Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany.
authors.forename: J
authors.initials: J
authors.lastname: Ullrich
authors.affiliation: Physikalisch-Technische Bundesanstalt, Bundesallee 100, 38116 Braunschweig, Germany. Institut für Quantenoptik, Leibniz Universität Hannover, Welfengarten 1, 30167 Hannover, Germany.
authors.forename: P O
authors.initials: PO
authors.lastname: Schmidt
authors.affiliation: Max-Planck-Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany. jose.crespo@mpi-hd.mpg.de.
authors.forename: J R Crespo
authors.initials: JR
authors.lastname: López-Urrutia