Investigation of the $6s6p{}_3{P}_0-4f^{13}5d6s^2$ ($J=2$) Clock Transition in ${}_{171}\mathrm{Yb}$ Atoms

High-precision atomic spectroscopy provides an invaluable and sensitive tool for exploring a wide range of physical questions. Here, we investigate the forbidden optical transition of the $6s6p{{}_{3}P}_0-4f^{13}5d6s^2$ ($J=2$) in ${}_{171}Yb$ atoms at the wavelength of 1695 nm, which exhibits the highest sensitivity to the variation of the fine-structure constant $\alpha$ compared to the current neutral optical clock. We obtain high-resolution transition spectroscopy in a one-dimensional optical lattice, and the measurement of its absolute frequency achieves kHz-level accuracy. Meanwhile, several essential atomic constants are also determined, including the electric-dipole ($E1$) magic wavelengths, as well as the hyperpolarizabilities and tensor polarizabilities around the $E1$ magic wavelengths. Additionally, we derive the hyperfine constant for the $J=2$ state from the measured absolute frequencies $1123252.3\pm 2.0\mathrm{kHz}$, providing a sixfold enhancement in the uncertainty reduction compared to the recent result. We anticipate that this work will prompt further investigation of the additional clock transition at 1695 nm in ${}_{171}Yb$ atoms. Together with the well-established ${}_1{S}_0\text{−}{}_3{P}_0$ transition, many fundamental and new physics research, such as the time variation of $\alpha$, ultralight dark-matter searches, Lorentz violation, etc., will enable new bounds and measurements with unprecedented precision.