Frequency measurement of the \({}^{1}{{\rm{S}}}_{0},F=5/2\,\leftrightarrow {}^{3}{{\rm{P}}}_{1},F=7/2\) transition of 27Al+ via quantum logic spectroscopy with 40Ca+

We perform quantum logic spectroscopy with a 27Al+/40Ca+ mixed ion crystal in a linear Paul trap for a measurement of the \({(3{s}^{2}){}^{1}{{\rm{S}}}_{0}\leftrightarrow (3s3p)}^{3}{{\rm{P}}}_{1},F=7/2\) intercombination transition in 27Al+. Towards this end, Ramsey spectroscopy is used for probing the transition in 27Al+ and the \((4{s}^{2}){{\rm{S}}}_{1/2}\leftrightarrow \,(4s3d){{\rm{D}}}_{5/2}\) clock transition in 40Ca+ in interleaved measurements. By using the precisely measured frequency of the clock transition in 40Ca+ as a frequency reference, we determine the frequency of the intercombination line to be \({\nu }_{{}^{1}{{\rm{S}}}_{0}\leftrightarrow {}^{3}{{\rm{P}}}_{1},F=7/2}\) = 1 122 842 857 334 736 (85) Hz and the Landé g-factor of the excited state to be \({g}_{{}^{3}{{\rm{P}}}_{1},F=7/2}\) = 0.428 133(2).