Estimation of BBR shift due to Stark effect for the Microwave $^{113}$Cd$^{+}$ Ion Clock

TL;DR

This paper precisely calculates the black-body radiation Stark shift for the $^{113}$Cd$^+$ ion clock transition using advanced relativistic many-body theories, improving the accuracy of systematic shift estimates.

Contribution

It provides a more accurate value of the BBR Stark shift coefficient for the $^{113}$Cd$^+$ ion clock using rigorous all-order relativistic calculations, which was previously estimated roughly.

Findings

Calculated the BBR Stark shift coefficient as -1.815(77) × 10^{-16}.

Used all-order relativistic many-body theories for precise hyperfine polarizability calculations.

Enhanced the accuracy of systematic shift estimates for the $^{113}$Cd$^+$ ion clock.

Abstract

The microwave clock frequency of the $|5s~^2S_{1/2}, F=0,m_F=0 \rangle \leftrightarrow |5s~^2S_{1/2}, F=1,m_F=0 \rangle$ transition in the $^{113}$Cd$^+$ ion has been reported as 15199862855.0192(10) Hz [Opt. Lett. {\bf 40}, 4249 (2015)]. Fractional systematic due to the black-body radiation (BBR) shift ($\beta$) arising from the Stark effect in the above clock transition was used as $-1.1 \times 10^{-16}$ from our unpublished preliminary estimation. We present here a precise value as $\beta=-1.815(77) \times 10^{-16}$ by carrying out rigorous calculations of third-order polarizabilities of the hyperfine levels associated with the clock transition. This is determined by evaluating matrix elements of the magnetic dipole hyperfine interaction Hamiltonian, electric dipole operator and energies between many low-lying states of $^{113}$Cd$^+$. We employ all-order relativistic many-body theories in the frameworks of Fock-space coupled-cluster and relativistic multi-configuration Dirac-Fock methods.