Isotope shifts of natural Sr+ measured by laser fluorescence in a sympathetically cooled Coulomb crystal

Abstract

We measured by laser spectroscopy the isotope shifts between naturally-occurring even-isotopes of strontium ions for both the $5s{}^2{S}_{1/2}\to 5p{}^2{P}_{1/2}$ (violet) and the $4d{}^2{D}_{3/2}\to 5p{}^2{P}_{1/2}$ (infrared) dipole-allowed optical transitions. Fluorescence spectra were taken by simultaneous measurements on a two-component Coulomb crystal in a linear Paul trap containing $10^3$--$10^4$ laser-cooled Sr${}^{+}$ ions. The isotope shifts are extracted from the experimental spectra by fitting the data with the analytical solution of the optical Bloch equations describing a three-level atom in interaction with two laser beams. This technique allowed us to increase the precision with respect to previously reported data obtained by optogalvanic spectroscopy or fast atomic-beam techniques. The results for the $5s{}^2{S}_{1/2}\to 5p{}^2{P}_{1/2}$ transition are ${\nu }_{88}-{\nu }_{84}=+378(4)$ MHz and ${\nu }_{88}-{\nu }_{86}=+170(3)$ MHz, in agreement with previously reported measurements. In the case of the previously unexplored $4d{}^2{D}_{3/2}\to 5p{}^2{P}_{1/2}$ transition we find ${\nu }_{88}-{\nu }_{84}=-828(4)$ MHz and ${\nu }_{88}-{\nu }_{86}=-402(2)$ MHz. These results provide more data for stringent tests of theoretical calculations of the isotope shifts of alkali-metal-like atoms. Moreover, they simplify the identification and the addressing of Sr${}^{+}$ isotopes for ion frequency standards or quantum-information-processing applications in the case of multi-isotope ion strings.

19 pages; 5 figures; accepted on Phys. Rev. A (http://pra.aps.org/)

References in corpus (2)

• Memory coherence of a sympathetically cooled trapped-ion qubit
• Precision measurement of the 5 2S1/2 - 4 2D5/2 quadrupole transition isotope shift between 88Sr+ and 86Sr+

Cited by in corpus (2)

• Precision measurement of the branching fractions of the 5p 2 P 1/2 state in 88 Sr + with a single ion in a micro fabricated surface trap
• Laser-cooled ytterbium ion frequency standard