Radio frequency field-induced persistent long-range ordered structures in two-species ion Coulomb crystals

Abstract

We report on the observations of strikingly persistent (lifetimes of ∼10 s) three-dimensional long-range ordered structures in the central 40Ca+ ion component of 40Ca+–44Ca+ two-species ion Coulomb crystals in a linear Paul trap. Molecular dynamics simulations strongly indicate that the observed structures are a hitherto unpredicted consequence of an effective anisotropy in the inter-particle interaction induced by the radio frequency quadrupole-trapping field. The results have implications for such diverse research fields as cold molecular ion studies and quantum information processing.