Realization And The Performance Evaluation Of The⁴⁰Ca⁺Optical Frequency Standard

Optical frequency standards have been significantly developed recently thanks to the invention of optical frequency comb and the development of the ultra-narrow-linewidth laser technology. Optical frequency standards are developed worldwide nowadays, either based on single trapped ions or based on trapped atoms in optical lattices. A single40Ca+ion has been proposed to be one of the candidates for the optical frequency standards, with a lifetime of the metastable level of～1s and a clock transition natural linewidth of～0.16Hz, which corresponds to a very high Q at1015level. We are developing an optical frequency standard based on a single trapped40Ca+ion, the ultra-narrow-linewidth laser is locked to the40Ca+clock transitions, and the systematic shifts of the40Ca+optical frequency standard was evaluated. After that, the absolute frequency of the clock transition was measured using the GPS system. The topics covered by this thesis are categorized as follows.1. The miniature Paul trap was optimized.40Ca+ions were prepared using photon ionization method. Based on the single trapped ion, the excess micromotion was well compensated by adjusting the trap electrodes using rf-photon correlation method, and the ion could stay in the trap for17days at longest.2. The lasers used in the experiment were optimized, both on the laser linewidth and the frequency stability. The heterodyne beat signal of the two729nn lasers was detected, and the linewidth of the beating result was less than10Hz. The cooling and repumping lasers were also frequency stabilized using transfer cavities.3. The40Ca+ion optical frequency standard system was locked. After the controlling of the lasers, electric field, and the magnetic field, the optical frequency standard system can be locked for more than two days at longest.4. Systematic frequency shifts of the40Ca+ion optical frequency standard system were studied and the overall systematic uncertainty of the clock resonance was smaller than1×10-15. After that, we did a measurement of the40Ca+clock transition frequency with respect to the SI second through the Global Positioning System and the overall measurement uncertainty was at10-15level.