Precise characterization of a New Clock Transition in Ytterbium

Optical lattice clocks play an important role in state-of-the-art atomic clocks, with multiple species achieving fractional uncertainties of 10^-18 or less. Such highly accurate clocks are now used as quantum sensors for fundamental physics searches. One of the transitions suitable for such quantum sensors is the 6s^{2 1}S₀ - 4f¹³ 5d 6s² (J=2) transition in neutral ytterbium at 431 nm. The excited state of this transition is theoretically predicted to be highly sensitive to multiple fundamental physics searches. The transition was observed experimentally for the first time in 2023. With atoms trapped in an optical lattice, Hertz-level precision spectroscopy is ready to be performed. We are developing an optical lattice clock system based on this clock transition. In this talk, we describe the characterization of the transition to list up the systematic uncertainties. The realization of an optical lattice clock with this new clock transition in Yb is expected to enable continuous frequency comparison with conventional optical lattice clocks, providing a search for the variation of the fine structure constant. Also, isotope shift measurements with this high accuracy can deepen our understanding of nuclear structure and the search for fifth forces between an electron and a neutron.