The Research Of The Optical Clock Transition Spectrum Of Ytterbium Atoms In 1D Optical Lattice

In recent years, the research of optical lattice clock based on neural atoms has made a rapid progress. The stability and uncertainty of optical clock have stepped into the order of magnitude of 10-18. It is better than cesium fountain clock, which is used for the international definition of second. Optical clock with high-precision is not only the key technology in time transport and global positioning system(GPS), but also the important tool in precision measurement physics.171Yb atom is an important candidate of optical frequency standard due to a narrow linewidth clock transition less than 10 mHz. So far, the instability of optical lattice clock based on 171Yb atoms has reached 1.6X10-18(25000s), and its uncertainty is expected to get into the magnitude of 10’19. Based on previous several years of technical accumulation, I succeed completing the interrogation of clock transition and obtaining Hertz-level clock spectra during the graduate student period. My main results are summarized as follows:1. The frequency locking systems of 399 nm and 556 nm lasers have been optimized. The 399 nm laser is locked with the modulation transfer spectroscopy(MTS), and the 556 nm laser is controlled with Pound-Drever-Hall(PDH) technique on a Fabry-Perot cavity together with fluorescence spectroscopy simultaneously. The short-term jitter of frequency is less than their natural linewidth and the laser can be locked more than 5 days, and their performance meets the requirements of optical clock experiment.2. Loading optical lattice with cold ytterbium atoms at magic wavelength has been realized. With delicated control of the temperature and density, the loading efficiency reaches 2% with the typical experimental parameters, the number of atoms in the lattice gets up to 5×104, the typical lifetime exceeds 5 s.3. The motional sideband spectra have been obtained. A high signal-to-noise ratio motional sideband spectra are observed with normalized shelving detection, and through the analysis of the shape of the spectrum, the lattice depth is estimated around 83μK, the temperature around 35μK and 28μK in longitudinal and transverse direction, respectively.4. The Hertz-level clock transition spectrum is observed. With the stray magnetic field cancelation, power broadening suppression and spin polarization, the linewidth of clock transition is reduced from kiloHertz to Hertz level. A clock transition spectrum with 5.9Hz linewidth is obtained under 170ms detection time, which is close to the Fourier limit linewidth.5. A new nondestructive measurement method on 171Yb optical lattice clock is studied preliminary. The AC stark shift of 1S0-3P1 transition is detected in optical lattice, and the theoretical analysis is done based on the detection results.