Study on the clock-transition spectrum of cold¹⁷¹Yb ytterbium atoms

We present a detailed study of the clock-transition spectrum of cold ¹⁷¹Yb ytterbium atoms in a 1D optical lattice. A typical clock-transition spectrum with a carrier-sideband structure is observed. After minimizing the power broadening effect and compensating the stray magnetic field, the carrier linewidth is narrowed to about 16 Hz for a 60 ms interrogation time. By increasing the interrogation time to 150 ms, the linewidth is further reduced to 6.8 Hz. By applying the bias magnetic field parallel to the clock-laser polarization, a two-peak spectrum corresponding to two π transitions is obtained. Finally, spin polarization of atoms to a single desired Zeeman sublevel of the ground state is also demonstrated. The presented results will be very useful for developing better optical lattice clocks.