Penning-trap eigenfrequency measurements with optical radiofrequency detectors

• Published in: Physical review research Vol. 6; no. 1; p. L012001
• Main Authors: Berrocal, J., Hernández, A., Arrazola, I., Domínguez, F., Carrasco-Sanz, A., Fernández, F. J., Block, M., Rodríguez, D.
• Format: Journal Article
• Language: English
• Published: American Physical Society 01.01.2024
• ISSN: 2643-1564; 2643-1564
• DOI: 10.1103/PhysRevResearch.6.L012001

We use an electric-dipole laser-driven transition to precisely measure the cyclotron-frequency ratios of the pairs ^{42}Ca^{+}−^{40}Ca^{+}, ^{44}Ca^{+}−^{40}Ca^{+}, and ^{48}Ca^{+}−^{40}Ca^{+} 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 (^{40,42,44,48}Ca^{+}) 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.