Molecular dynamics simulation of a sympathetically-cooled ^(113)Cd^(+)ion crystal system is achieved.Moreover,the relationship between ions’axial temperature and different electric parameters,including radio frequenc...Molecular dynamics simulation of a sympathetically-cooled ^(113)Cd^(+)ion crystal system is achieved.Moreover,the relationship between ions’axial temperature and different electric parameters,including radio frequency voltage and endcap voltage is depicted.Under stable trapping condition,optimum radio frequency voltage,corresponding to minimum temperature and the highest cooling efficiency,is obtained.The temperature is positively correlated with end-cap voltage.The relationship is also confirmed by a sympathetically-cooled ^(113)Cd^(+) microwave clock.The pseudo-potential model is used to illustrate the relationship and influence mechanism.A reasonable index,indicating ions’temperature,is proposed to quickly estimate the relative ions’temperature.The investigation is helpful for ion crystal investigation,such as spatial configuration manipulation,sympathetic cooling efficiency enhancement,and temporal evolution.展开更多
In the ^(199)Hg^(+) ion microwave clock,the Zeeman decoherence effect caused by the overlapping of Zeeman sidebands and the radial secular motion sidebands will decrease the contrast of the Ramsey fringe,thus reducing...In the ^(199)Hg^(+) ion microwave clock,the Zeeman decoherence effect caused by the overlapping of Zeeman sidebands and the radial secular motion sidebands will decrease the contrast of the Ramsey fringe,thus reducing the signal-to-noise ratio of the spectra.In this paper,the Zeeman decoherence effect is analyzed theoretically and investigated experimentally.A simplified model is built to describe the Ramsey spectral probability,in which the transverse relaxation time T2 is introduced to characterize the influence of the Zeeman decoherence effect phenomenologically.The experiments were carried out on a linear quadrupole trap ^(199)Hg^(+) ion clock.The results show that the probability model matches well with the experimental data,and the magnetic field value should be more than 150 mGs(1 Gs=10^(-4) T)to avoid the Zeeman decoherence effect.展开更多
We report the recent progress of our pulsed optically pumped（POP） vapor cell rubidium clock with dispersive detection.A new compact physics package is made.A rubidium cell with a high precision buffer gases mixing r...We report the recent progress of our pulsed optically pumped（POP） vapor cell rubidium clock with dispersive detection.A new compact physics package is made.A rubidium cell with a high precision buffer gases mixing ratio is obtained,and the temperature controlling system is renovated to reduce fractional frequency sensitivity to temperature variation.The resolution of the servo control voltage is also optimized.With these improvements,a clock frequency stability of 3.53×10-13 at 1s is obtained,and a fractional frequency stability of 4.91×10-15 is achieved at an average time of τ=2000 s.展开更多
基金Project supported by the Beijing Natural Science Foundation(Grant No.1202011)the Tsinghua University Initiative Scientific Research Program,the National Natural Science Foundation of China(Grant No.12073015)the National Key Research and Development Program of China(Grant No.2016YFA0302101).
文摘Molecular dynamics simulation of a sympathetically-cooled ^(113)Cd^(+)ion crystal system is achieved.Moreover,the relationship between ions’axial temperature and different electric parameters,including radio frequency voltage and endcap voltage is depicted.Under stable trapping condition,optimum radio frequency voltage,corresponding to minimum temperature and the highest cooling efficiency,is obtained.The temperature is positively correlated with end-cap voltage.The relationship is also confirmed by a sympathetically-cooled ^(113)Cd^(+) microwave clock.The pseudo-potential model is used to illustrate the relationship and influence mechanism.A reasonable index,indicating ions’temperature,is proposed to quickly estimate the relative ions’temperature.The investigation is helpful for ion crystal investigation,such as spatial configuration manipulation,sympathetic cooling efficiency enhancement,and temporal evolution.
基金Project supported by the National Key Research and Development Program of China(Grant No.2022YFB3904002).
文摘In the ^(199)Hg^(+) ion microwave clock,the Zeeman decoherence effect caused by the overlapping of Zeeman sidebands and the radial secular motion sidebands will decrease the contrast of the Ramsey fringe,thus reducing the signal-to-noise ratio of the spectra.In this paper,the Zeeman decoherence effect is analyzed theoretically and investigated experimentally.A simplified model is built to describe the Ramsey spectral probability,in which the transverse relaxation time T2 is introduced to characterize the influence of the Zeeman decoherence effect phenomenologically.The experiments were carried out on a linear quadrupole trap ^(199)Hg^(+) ion clock.The results show that the probability model matches well with the experimental data,and the magnetic field value should be more than 150 mGs(1 Gs=10^(-4) T)to avoid the Zeeman decoherence effect.
基金supported by the National Natural Science Foundation of China under Grant Nos.91536220 and 11504393
文摘We report the recent progress of our pulsed optically pumped（POP） vapor cell rubidium clock with dispersive detection.A new compact physics package is made.A rubidium cell with a high precision buffer gases mixing ratio is obtained,and the temperature controlling system is renovated to reduce fractional frequency sensitivity to temperature variation.The resolution of the servo control voltage is also optimized.With these improvements,a clock frequency stability of 3.53×10-13 at 1s is obtained,and a fractional frequency stability of 4.91×10-15 is achieved at an average time of τ=2000 s.
