Precision spectroscopy with a single <sup>40</sup>Ca<sup>+</sup> ion in a Paul trap<xref ref-type="fn" rid="cpb150346fn1">*</xref>

Precision spectroscopy with a single ⁴⁰Ca⁺ ion in a Paul trap*

Guan Hua^a),^b), Huang Yao^a),^b), Liu Pei-Liang^a),^b), Bian Wu^a),^b),^c), Shao Hu^a),^b),^c), Gao Ke-Lin^a),^b)†

Overview of setup for the frequency comparison of two ⁴⁰Ca⁺ optical frequency standards. AO: acousto-optic modulator; PM: polarization maintaining; BS: polarized beam splitter.