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arXiv · 2308.14884

Penning-trap eigenfrequency measurements with optical radiofrequency detectors

Joaquín Berrocal·Alejandro Hernández·Íñigo Arrazola·Francisco Domínguez·Ana Carrasco-Sanz·Francisco Javier Fernández·Michael Block·Daniel Rodríguez
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Abstract

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 ($T\approx 1$~mK) ion serves, together with photon-counting and/or photon-imaging units, as a radiofrequency detector covering a broad-band frequency spectrum, in the present case from kHz to a few MHz. Such detectors ($^{40,42,44,48}$Ca$^{\scriptsize{+}}$) allow measuring extremely small forces, with measured normalized sensitivities down to $7.4(3.5)$ yN$/\sqrt{\text{Hz}}$ and $24.9(9.9)$ yN$/\sqrt{\text{Hz}}$ in the MHz and kHz regime, respectively. 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.

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BibTeXRIS

Joaquín Berrocal, Alejandro Hernández, Íñigo Arrazola, Francisco Domínguez, Ana Carrasco-Sanz, Francisco Javier Fernández, Michael Block, Daniel Rodríguez. 2023-08-28. Penning-trap eigenfrequency measurements with optical radiofrequency detectors. https://doi.org/10.1103/physrevresearch.6.l012001

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