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11.
Frequency comparison is one of the most efficient ways to evaluate the performance of a frequency standard. Based on the pre-existing 40^Ca+ optical frequency standard, we set up the second 40^Ca^+ optical frequency standard, which has been improved in the materials and structure of ion traps for better control of the magnetic field. After the compensation, the residual magnetic field at the position of the ion is adjusted to be~500nT with a long time jitter of~10nT, which is better than the pre-existing 40^Ca^+ optical frequency standard. We realize the '4-point-closed-loop locking' on the second 40^Ca+ optical frequency standard after a series of preparatory works. Through half an hour of measurement time, the two frequency standards exhibited a stability of 2.1 × 10^-13.τ^1/2 and a relative frequency difference of 1.5 (2.9)Hz. 相似文献
12.
Determining the structural phase transition point from the temperature of ~(40)Ca~+ Coulomb crystal 下载免费PDF全文
We observed the linear-to-zigzag structural phase transition of a ^40Ca^+ crystal in a homemade linear Paul trap. The values of the total temperature of the ion crystals during the phase transition are derived using the molecular-dynamics(MD) simulation method. A series of simulations revealed that the ratio of the radial to axial secular frequencies has a dependence on the total temperature that obeys different functional forms for linear and zigzag structures, and the transition point occurs where these functions intersect; thus, the critical value of the ratio of secular frequencies that drives the structure phase transition can be derived. 相似文献
13.
Potential distribution is an important characteristic for evaluating the performance of an ion trap. Here, we analyze and optimize the potential distribution of an endcap ion trap for single-ion trapping.We obtain an optimal endcap radius of225 μm–250 μm, endcap-shield gap of ~ 250 μm, and inter-endcap distance of 540 μm–590 μm. The simulation method for analysis can also be applied to other ion traps, which is useful for improving the design and assembly of ion traps. 相似文献
14.
Relationship measurement between ac-Stark shift of ~(40)Ca~+ clock transition and laser polarization direction 下载免费PDF全文
Ac-Stark shift of atom levels is caused by an ac-electromagnetic field. As an electromagnetic wave, laser light does induce ac-Stark shift. It is proved experimentally that if the light is linearly polarized, the dynamic polarizability changes with polarization direction. The polarization direction of the linearly-polarized laser is tuned by 720?, and the ac-Stark shifts of the 4S_(1/2),m=±1/2→3D_(5/2,m=±1/2) clock transitions in ~(40)Ca~+ are measured in steps of 10?. The frequency shifts change with laser polarization in a periodical manner and have values opposite to each other. 相似文献
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