A microwave frequency standard based on laser-cooled171Yb+ions at Tsinghua University has been investigated. More than 105171Yb+ions were stably trapped for over 40 hours. The ground-state hyperfine splitting frequency of171Yb+was determined to be 12642812118.4672(8) Hz with a fractional frequency uncertainty of 6.33×10−14. Our work is in a continuous line with that of other scholars.
A microwave frequency standard based on laser-cooled171Yb+ions at Tsinghua University has been investigated. More than 105171Yb+ions were stably trapped for over 40 hours. The ground-state hyperfine splitting frequency of171Yb+was determined to be 12642812118.4672(8) Hz with a fractional frequency uncertainty of 6.33×10−14. Our work is in a continuous line with that of other scholars.
Abstract As a candidate for the next generation microwave clock, microwave atomic clocks based on trapped ions are currently studied worldwide. Since 2010, our team at Tsinghua University has been committed to developing a high-performance 113Cd+ microwave ion clock. In 2021, the laser-cooled cadmium-ion microwave clock constructed in our laboratory demonstrated remarkable performance, with a short-term instability of 4.2 × 10 − 13 / τ and a relative frequency uncertainty of 1.8 × 10−14, improving nearly three orders of magnitude compared to the result from JPL. The 0-0 ground-state hyperfine splitting frequency of 113Cd+ was determined to be 15199862855.02799(27) Hz, currently the most accurate measurement result for this transition frequency. Apart from that, we introduced the sympathetic cooling technology into the experiment of cadmium-ion microwave clock. Using 40Ca+ as the coolant ion, we obtained Ramsey patterns with a free evolution time of up to 100 seconds, ultimately improving the short-term instability of the system to 3.48 × 10 − 13 / τ . Moreover, a microwave frequency standard based on laser-cooled 171Yb+ ions has also been developed in our laboratory since 2021. The short-term frequency instability was measured to be 8.5 × 10 − 13 / τ . The ground-state hyperfine splitting frequency of 171Yb+ was determined to be 12642812118.4674(8) Hz with a fractional frequency uncertainty of 6.33 × 10−14.
We present a transportable laser-cooled ion microwave clock based on the ground-state hyperfine splitting of 171 Yb + . The system achieves a systematic uncertainty of 7.8×10 −15 and a short-term frequency stability of 9.5×10 −13 / τ . Enhancements to the magnetic-field system suppress the decoherence process in the multi-body ion ensemble and reduce the second-order Zeeman frequency shift by a factor of two. The absolute microwave frequency is measured to be 12 642 812 118.468 6(3) Hz, consistent with the previous measurements and demonstrating twice the precision of the current state-of-the-art.
As a candidate for the next generation microwave clock, microwave atomic clocks based on trapped ions are currently studied worldwide. Since 2010, our team at Tsinghua University has been committed to developing a high-performance113Cd+microwave ion clock. In 2021, the laser-cooled cadmium-ion microwave clock constructed in our laboratory demonstrated remarkable performance, with a short-term instability of4.2×10−13/τand a relative frequency uncertainty of1.8×10−14, improving nearly three orders of magnitude compared to the result from JPL. The ground-state hyperfine splitting of113Cd+was determined to be 15199862855.02799(27) Hz, currently the most accurate measurement result for this transition frequency. Apart from that, we introduced the sympathetic cooling technology into the experiment of cadmium-ion microwave clock. Using40Ca+as the coolant ion, we obtained Ramsey patterns with a free evolution time of up to 100 seconds, ultimately improving the short-term instability of the system to3.48×10−13/τ.
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-cooled113Cd+ions developed at Tsinghua University. Based on the current experimental setup, the ground-state hyperfine splitting of113Cd+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.
We present the determination of the ground-state hyperfine splitting (νHFS) in laser-cooled 171Yb+ ions using our microwave quantum frequency standard (QFS). Employing Ramsey spectroscopy in a closed-loop measurement configuration, we have achieved a νHFS value of 12 642 812 118 469.0(8) mHz with a fractional uncertainty of 6.6×10−14. This result aligns with previously reported values and represents the highest accuracy reported to date for such measurements conducted in a single-shot closed-loop configuration, without averaging over multiple dates. The development of this accurate 171Yb+ microwave QFS holds promise as a transportable time-frequency reference for satellite navigation systems.
We report on the development of a microwave frequency standard based on a laser-cooled 171 Y b + ion trap system. The electronics , lasers, and magnetic shields are integrated into a single physical package. With over 105 ions are stably trapped, the system offers a high signal-to-noise ratio Ramsey line-shape. In comparison with previous work, the frequency instability of a 171 Y b + microwave clock was further improved to 8.5 × 10 − 13 / τ for averaging times between 10 and 1000 s. Essential systematic shifts and uncertainties are also estimated.