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Hertz-Level Clock Spectroscopy of 171Yb Atoms in a One-Dimensional Optical Lattice

An ultra-narrow spectroscopy of clock transition with high signal-to-noise ratio is crucial for a high-performance atomic optical clock. We present a detailed study about how to obtain a Hertz-level clock transition spectrum of 171Yb atoms. About 4 × 104 atoms are loaded into a one-dimensional optical lattice with a magic wavelength of 759 nm, and a long lifetime of 3 s is realized with the lattice power of 1 W. Through normalized shelving detection and spin polarization, 171Yb clock spectroscopy with a Fourier-limited linewidth of 5.9 Hz is obtained. Our work represents a key step toward an ytterbium optical clock with high frequency stability.