Study of optical clocks based on ultracold ¹⁷¹Yb atoms

The optical atomic clocks have the potential to transform global timekeeping, relying on the state-of-the-art accuracy and stability, and greatly improve the measurement precision for a wide range of scientific and technological applications. Herein we report on the development of the optical clock based on ¹⁷¹Yb atoms confined in an optical lattice. A minimum width of 1.92-Hz Rabi spectra has been obtained with a new 578-nm clock interrogation laser. The in-loop fractional instability of the ¹⁷¹Yb clock reaches 9.1×10^-18 after an averaging over a time of 2.0×10⁴ s. By synchronous comparison between two clocks, we demonstrate that our ¹⁷¹Yb optical lattice clock achieves a fractional instability of 4.60×10^-16/√τ.