Determination of the 5d6s 3D1 state lifetime and blackbody radiation   clock shift in Yb
  The Stark shift of the ytterbium optical clock transition due to room temperature blackbody radiation is dominated by a static Stark effect, which was recently measured to high accuracy [J. A. Sherman et al., Phys. Rev. Lett. 108, 153002 (2012)]. However, room temperature operation of the clock at 10^{-18} inaccuracy requires a dynamic correction to this static approximation. This dynamic correction largely depends on a single electric dipole matrix element for which theoretically and experimentally derived values disagree significantly. We determine this important matrix element by two independent methods, which yield consistent values. Along with precise radiative lifetimes of 6s6p 3P1 and 5d6s 3D1, we report the clock's blackbody radiation shift to 0.05% precision. 
K. Beloy, J. A. Sherman, N. D. Lemke, N. Hinkley, C. W. Oates, A. D.   Ludlow
physics.atom-ph