Sympathetic Crystallization of Trapped Ions

We have created multispecies Coulomb crystals in a linear Paul trap containing up to a few hundred ions of which more than 50% were cooled only sympathetically through the Coulomb interaction with laser-cooled Mg+ ions. In an extreme case, one laser-cooled ion maintained order in a 15ion string. Ion species segregation was obtained by radiation pressure. Previous experiments and molecular dynamics simulations suggest the temperature is 10mK or lower. These results indicate that a wide range of atomic and molecular ions can be cooled and localized in linear Paul traps which is important for improvements in spectroscopic studies of such ions. copyright 1999 The American Physical Society