Towards a high-performance microwave frequency standard based on 113Cd+ ions

Microwave frequency standards based on ions are promising as the next generation atomic clocks. This paper reports the recent progresses of the microwave frequency standard based on laser-cooled ¹¹³Cd⁺ ions developed at Tsinghua University. Based on the current experimental setup, the ground-state hyperfine splitting of ¹¹³Cd⁺ is measured with higher precision and a better short-term frequency stability is obtained than before. To improve the performance of the Cd⁺ clock further, a new experimental setup with dual-traps is designed, and bi-ions operation is proposed.