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

我们研究混合钡-tter链中线性RF陷阱中径向离子运动的同情冷却。钡离子是多普勒冷却的，而through离子是通过与冷钡离子的相互作用而冷却的。我们通过测量离子链中所有径向法向运动的平均占据量子数和温度来估算同情冷却的效率。已探究了两个钡和两个离子链中的完整有序集，并且我们显示了所有链构型的平均热占用数在很大程度上取决于阱的长宽比。我们展示了所有径向法向模式的有效同情冷却，陷阱深宽比约为2.9。