Frequency measurement of the 1 S 0 , F = 5 / 2 ↔ 3 P 1 , F = 7 / 2 transition of 27Al+ via quantum logic spectroscopy with 40Ca+

We perform quantum logic spectroscopy with a 27 Al + / 40 Ca + mixed ion crystal in a linear Paul trap for a measurement of the intercombination transition in 27 Al + . Towards this end, Ramsey spectroscopy is used for probing the transition in 27 Al + and the clock transition in 40 Ca + in interleaved measurements. By using the precisely measured frequency of the clock transition in 40 Ca + as a frequency reference, we determine the frequency of the intercombination line to be = 1 122 842 857 334 736 (85) Hz and the Landé g -factor of the excited state to be = 0.428 133(2).