Efficient sympathetic cooling in mixed barium and ytterbium ion chains

We study sympathetic cooling of the radial ion motion in a linear RF trap mixed barium-ytterbium chains. Barium ions are Doppler-cooled, while ytterbium cooled through their interaction with cold barium ions. estimate efficiency by measuring average occupation quantum numbers, and thus temperature, all normal modes chain. The full set orderings chain two have been probed, we show that thermal numbers for configurations strongly depend on aspect ratio. demonstrate efficient ratio approximately 2.9.