Blackbody radiation shift in the Sr optical atomic clock

TL;DR

This paper accurately calculates the blackbody radiation shift in the Sr optical atomic clock, resolving previous discrepancies and highlighting the significance of dynamic corrections for clock accuracy.

Contribution

The study provides high-precision calculations of polarizabilities and BBR shifts in Sr, aligning theory with recent experiments and emphasizing the importance of dynamic corrections.

Findings

Calculated polarizabilities match recent experimental data.

Evaluated the dynamic correction to the BBR shift with 1% uncertainty.

Identified the large impact of dynamic correction on clock uncertainty.

Abstract

We evaluated the static and dynamic polarizabilities of the 5s^2 ^1S_0 and 5s5p ^3P_0^o states of Sr using the high-precision relativistic configuration interaction + all-order method. Our calculation explains the discrepancy between the recent experimental 5s^2 ^1S_0 - 5s5p ^3P_0^o dc Stark shift measurement \Delta \alpha = 247.374(7) a.u. [Middelmann et. al, arXiv:1208.2848 (2012)] and the earlier theoretical result of 261(4) a.u. [Porsev and Derevianko, Phys. Rev. A 74, 020502R (2006)]. Our present value of 247.5 a.u. is in excellent agreement with the experimental result. We also evaluated the dynamic correction to the BBR shift with 1 % uncertainty; -0.1492(16) Hz. The dynamic correction to the BBR shift is unusually large in the case of Sr (7 %) and it enters significantly into the uncertainty budget of the Sr optical lattice clock. We suggest future experiments that could further reduce the present uncertainties.