Penning-trap eigenfrequency measurements with optical radiofrequency detectors

We use an electric-dipole laser-driven transition to precisely measure the cyclotron-frequency ratios of the pairs 42Ca+−40Ca+, 44Ca+−40Ca+, and 48Ca+−40Ca+ in a 7-tesla Penning trap. A single laser-cooled (T≈1 mK) ion serves, together with photon-counting and photon-imaging units, as a radiofrequency detector covering a broadband frequency spectrum, in the present case from kHz to a few MHz. Such detectors (40,42,44,48Ca+) allow measuring extremely small forces increasing the sensitivity in Penning-trap mass spectrometry. The direct determination of the ions' amplitudes makes a cyclotron-frequency measurement process more robust against inhomogeneities of the magnetic field and/or deviations of the electric quadrupole field due to mechanical imperfections of the trap.Ministerio de Ciencia, Innovación y Universidades through Grant No. PID2022-141496NB-I00 funded by MCIN/AEI/10.13039/501100011033 and by ERDF A way of making Europe, and Grant No. PID2019-104093GB-I00 funded by MCIN/AEI/10.13039/501100011033FEDER/Junta de Andalucía-Consejería de Universidad, Investigación e Innovación through Project No. P18-FR-3432Spanish Ministry of Education through Ph.D. fellowship FPU17/02596University of Granada “Laboratorios Singulares 2020”European Research Council (Contract No. 278648-TRAPSENSOR)Projects No. FPA2015-67694-P (funded by MCIN/AEI/10.13039/501100011033 and by ERDF A way of making Europe) and No. FPA2012-32076 (MCIN/FEDER)Infrastructure Projects No. UNGR10-1E-501, and No. UNGR13-1E-1830 (MCIN/FEDER/UGR), and No. EQC2018-005130-P (funded by MCIN/AEI/10.13039/501100011033 and by ERDF A way of making Europe)Infrastructure Projects No. INF-2011-57131 and No. IE2017-5513 (funded by Junta de Andalucía/FEDER)European Union’s Horizon 2020 research and innovation program under Grant Agreement No. 899354 (SuperQuLAN