Absolute frequency measurement of the ytterbium ion E3 optical clock transition using international atomic time

We report a revised absolute frequency measurement of the 171Yb ⁺ electric octupole optical clock transition of 642 121 496 772 645.17(22) Hz, with a fractional uncertainty of 3.4 × 10-16. This newer value, with lower uncertainty, is achieved through additional analysis of previously reported experimental data that links the optical frequency to the SI second through international atomic time (TAI). The new step in the data analysis involves a special computation of the fractional frequency offset between the scale interval of TAI and the SI second, over a time interval more closely matched to the experimental data acquisition period.