Ytterbium in Quantum Gases and Atomic Clocks: van der Waals Interactions and Blackbody Shifts

We evaluated the $C_6$ coefficients of Yb-Yb, Yb-alkali, and Yb-group II van der Waals interactions with 2% uncertainty. The only existing experimental result for such quantities is for the Yb-Yb dimer. Our value, $C_6=1929(39)\mathrm{a}.\mathrm{u}.$, is in excellent agreement with the recent experimental determination of 1932(35) a.u. We have also developed a new approach for the calculation of the dynamic correction to the blackbody radiation shift. We have calculated this quantity for the Yb $6s^2{}^{1}S_0-6s6p{}^{3}P_0^o$ clock transition with 3.5% uncertainty. This reduces the fractional uncertainty due to the blackbody radiation shift in the Yb optical clock at 300 K to the ${10}^{-18}$ level.