Precision Isotope Shift Measurements in Calcium Ions Using Quantum Logic Detection Schemes

Abstract

We demonstrate an efficient high-precision optical spectroscopy technique for single trapped ions with nonclosed transitions. In a double-shelving technique, the absorption of a single photon is first amplified to several phonons of a normal motional mode shared with a cotrapped cooling ion of a different species, before being further amplified to thousands of fluorescence photons emitted by the cooling ion using the standard electron shelving technique. We employ this extension of the photon recoil spectroscopy technique to perform the first high precision absolute frequency measurement of the D3/22→P1/22 transition in calcium, resulting in a transition frequency of f=346 000 234 867(96) kHz. Furthermore, we determine the isotope shift of this transition and the S1/22→P1/22 transition for Ca+42, Ca+44, and Ca+48 ions relative to Ca+40 with an accuracy below 100 kHz. Improved field and mass shift constants of these transitions as well as changes in mean square nuclear charge radii are extracted from this high resolution data. © 2015 American Physical Society.