Abstract In many of the high-precision optical frequency standards with trapped atoms or ions that are under development to date, the ac Stark shift induced by thermal radiation leads to a major contribution to the systematic uncertainty. We present an analysis of the inhomogeneous thermal environment experienced by ions in various types of ion traps. Finite element models which allow the determination of the temperature of the trap structure and the temperature of the radiation were developed for five ion trap designs, including operational traps at PTB and NPL and further optimized designs. Models were refined based on comparison with infrared camera measurement until an agreement of better than 10% of the measured temperature rise at critical test points was reached. The effective temperature rises of the radiation seen by the ion range from 0.8 K to 2.1 K at standard working conditions. The corresponding fractional frequency shift uncertainties resulting from the uncertainty in temperature are in the 10 −18 range for optical clocks based on the Sr + and Yb + E2 transitions, and even lower for Yb + E3, In + and Al + . Issues critical for heating of the trap structure and its predictability were identified and design recommendations developed.Abstract In many of the high-precision optical frequency standards with trapped atoms or ions that are under development to date, the ac Stark shift induced by thermal radiation leads to a major contribution to the systematic uncertainty. We present an analysis of the inhomogeneous thermal environment experienced by ions in various types of ion traps. Finite element models which allow the determination of the temperature of the trap structure and the temperature of the radiation were developed for five ion trap designs, including operational traps at PTB and NPL and further optimized designs. Models were refined based on comparison with infrared camera measurement until an agreement of better than 10% of the measured temperature rise at critical test points was reached. The effective temperature rises of the radiation seen by the ion range from 0.8 K to 2.1 K at standard working conditions. The corresponding fractional frequency shift uncertainties resulting from the uncertainty in temperature are in the 10 −18 range for optical clocks based on the Sr + and Yb + E2 transitions, and even lower for Yb + E3, In + and Al + . Issues critical for heating of the trap structure and its predictability were identified and design recommendations developed.

arXiv:1510.05556MetrologiaNov 12, 201564 citations

The Trapped Ion Frequency Standard: Current Status and Future Prospects

Lute Maleki

Jan 1, 19950 citations

Stray-field-induced quadrupole shift and absolute frequency of the 688-THz Y171b+ single-ion optical frequency standard

Chr. Tamm, S. Weyers, B. Lipphardt +1 more

We report experimental investigations of a single-ion optical frequency standard based on ${^{171}\text{Y}\text{b}}^{+}$ . The ion is confined in a cylindrically symmetric radiofrequency Paul trap. The reference transition is the ${^{2}S}_{1/2}(F=0)--{^{2}D}_{3/2}({F}^{\ensuremath{'}}=2)$ electric quadrupole transition at 688 THz. Using a differential measurement scheme, we determine the shift of the reference transition frequency that occurs due to the interaction of the electric quadrupole moment of the ${^{2}D}_{3/2}$ state with the gradient of the electrostatic stray field in the trap. We determine an upper limit for the instability of the quadrupole shift over times between 100 s to 20 h. We also observe the variations in the shift and in the applied stray-field compensation voltages that result from loading a new ion into the trap and during a subsequent storage period of 74 days. This information is utilized to measure the absolute frequency of the reference transition with an uncertainty that is a factor of 3 smaller than that of the previous measurement. Using a fiber laser based optical frequency comb generator and the cesium fountain clock CSF1 of PTB (Physikalisch-Technische Bundesanstalt), the frequency at 300 K temperature is determined as $688\text{ }358\text{ }979\text{ }309\text{ }306.62\ifmmode\pm\else\textpm\fi{}0.73\text{ }\text{Hz}$.We report experimental investigations of a single-ion optical frequency standard based on ${^{171}\text{Y}\text{b}}^{+}$. The ion is confined in a cylindrically symmetric radiofrequency Paul trap. The reference transition is the ${^{2}S}_{1/2}(F=0)--{^{2}D}_{3/2}({F}^{\ensuremath{'}}=2)$ electric quadrupole transition at 688 THz. Using a differential measurement scheme, we determine the shift of the reference transition frequency that occurs due to the interaction of the electric quadrupole moment of the ${^{2}D}_{3/2}$ state with the gradient of the electrostatic stray field in the trap. We determine an upper limit for the instability of the quadrupole shift over times between 100 s to 20 h. We also observe the variations in the shift and in the applied stray-field compensation voltages that result from loading a new ion into the trap and during a subsequent storage period of 74 days. This information is utilized to measure the absolute frequency of the reference transition with an uncertainty that is a factor of 3 smaller than that of the previous measurement. Using a fiber laser based optical frequency comb generator and the cesium fountain clock CSF1 of PTB (Physikalisch-Technische Bundesanstalt), the frequency at 300 K temperature is determined as $688\text{ }358\text{ }979\text{ }309\text{ }306.62\ifmmode\pm\else\textpm\fi{}0.73\text{ }\text{Hz}$.

Physical Review AOct 6, 2009103 citations

We report experimental investigations of a single-ion optical frequency standard based on

{^{171}\text{Y}\text{b}}^{+}

. The ion is confined in a cylindrically symmetric radiofrequency Paul trap. The reference transition is the ${^{2}S}_{1/2}(F=0)--{^{2}D}_{3/2}({F}^{\ensuremath{'}}=2)$ electric quadrupole transition at 688 THz. Using a differential measurement scheme, we determine the shift of the reference transition frequency that occurs due to the interaction of the electric quadrupole moment of the

{^{2}D}_{3/2}

state with the gradient of the electrostatic stray field in the trap. We determine an upper limit for the instability of the quadrupole shift over times between 100 s to 20 h. We also observe the variations in the shift and in the applied stray-field compensation voltages that result from loading a new ion into the trap and during a subsequent storage period of 74 days. This information is utilized to measure the absolute frequency of the reference transition with an uncertainty that is a factor of 3 smaller than that of the previous measurement. Using a fiber laser based optical frequency comb generator and the cesium fountain clock CSF1 of PTB (Physikalisch-Technische Bundesanstalt), the frequency at 300 K temperature is determined as $688\text{ }358\text{ }979\text{ }309\text{ }306.62\ifmmode\pm\else\textpm\fi{}0.73\text{ }\text{Hz}$.