Blackbody-radiation shift in a ⁴³Ca⁺ ion optical frequency standard

Motivated by the prospect of an optical frequency standard based on ⁴³Ca⁺, we calculate the blackbody-radiation (BBR) shift of the 4s_1∕2−3d_5∕2 clock transition, which is a major component of the uncertainty budget. The calculations are based on the relativistic all-order single-double method where all single and double excitations of the Dirac-Fock wave function are included to all orders of perturbation theory. Additional calculations are conducted for the dominant contributions in order to evaluate some omitted high-order corrections and estimate the uncertainties of the final results. The BBR shift obtained for this transition is 0.38(1) Hz. The tensor polarizability of the 3d_5∕2 level is also calculated and its uncertainty is evaluated as well. Our results are compared with other calculations.