scholarly journals An Evaluation of the Zeeman Shift of the 87Sr Optical Lattice Clock at the National Time Service Center

2020 ◽  
Vol 10 (4) ◽  
pp. 1440 ◽  
Author(s):  
Xiaotong Lu ◽  
Mojuan Yin ◽  
Ting Li ◽  
Yebing Wang ◽  
Hong Chang
Keyword(s):  
Magnetic Field ◽  
Optical Lattice ◽  
Average Frequency ◽  
Service Center ◽  
Time Service ◽  
First Order ◽  
Zeeman Shift ◽  
Frequency Correction ◽  
Overall Evaluation ◽  
Optical Lattice Clock

The Zeeman shift plays an important role in the evaluation of optical lattice clocks since a strong bias magnetic field is applied for departing Zeeman sublevels and defining a quantization axis. We demonstrated the frequency correction and uncertainty evaluation due to Zeeman shift in the 87Sr optical lattice clock at the National Time Service Center. The first-order Zeeman shift was almost completely removed by stabilizing the clock laser to the average frequency of the two Zeeman components of mF = ±9/2. The residual first-order Zeeman shift arose from the magnetic field drift between measurements of the two stretched-state center frequencies; the upper bound was inferred as 4(5) × 10−18. The quadratic Zeeman shift coefficient was experimentally determined as –23.0(4) MHz/T2 and the final Zeeman shift was evaluated as 9.20(7) × 10−17. The evaluation of the Zeeman shift is a foundation for overall evaluation of the uncertainty of an optical lattice clock. This measurement can provide more references for the determination of the quadratic coefficient of 87Sr.

Development of the strontium optical lattice clock at national time service center

2018 ◽  
Author(s):  
Mojuan Yin ◽  
Qinfang Xu ◽  
Yebing Wang ◽  
Jie Ren ◽  
Yang Guo ◽  
...  
Keyword(s):  
Optical Lattice ◽  
Service Center ◽  
Time Service ◽  
Optical Lattice Clock

Strontium optical lattice clock at the National Time Service Center

2018 ◽  
Vol 27 (2) ◽  
pp. 023701 ◽  
Author(s):  
Ye-Bing Wang ◽  
Mo-Juan Yin ◽  
Jie Ren ◽  
Qin-Fang Xu ◽  
Ben-Quan Lu ◽  
...  
Keyword(s):  
Optical Lattice ◽  
Service Center ◽  
Time Service ◽  
Optical Lattice Clock

scholarly journals Recent Advances Concerning the 87Sr Optical Lattice Clock at the National Time Service Center

2018 ◽  
Vol 8 (11) ◽  
pp. 2194 ◽  
Author(s):  
Yebing Wang ◽  
Xiaotong Lu ◽  
Benquan Lu ◽  
Dehuan Kong ◽  
Hong Chang
Keyword(s):  
Optical Lattice ◽  
Closed Loop ◽  
Frequency Instability ◽  
Frequency Noise ◽  
Allan Deviation ◽  
Service Center ◽  
Space Applications ◽  
Time Service ◽  
Optical Lattice Clock ◽  
Averaging Time

We review recent experimental progress concerning the 87Sr optical lattice clock at the National Time Service Center in China. Hertz-level spectroscopy of the 87Sr clock transition for the optical lattice clock was performed, and closed-loop operation of the optical lattice clock was realized. A fractional frequency instability of 2.8 × 10−17 was attained for an averaging time of 2000 s. The Allan deviation is found to be 1.6 × 10−15/τ1/2 and is limited mainly by white-frequency-noise. The Landé g-factors of the (5s2)1S0 and (5s5p)3P0 states in 87Sr were measured experimentally; they are important for evaluating the clock’s Zeeman shifts. We also present recent work on the miniaturization of the strontium optical lattice clock for space applications.

A transportable optical lattice clock at the National Time Service Center

2020 ◽  
Vol 29 (7) ◽  
pp. 070602 ◽  
Author(s):  
De-Huan Kong ◽  
Zhi-Hui Wang ◽  
Feng Guo ◽  
Qiang Zhang ◽  
Xiao-Tong Lu ◽  
...  
Keyword(s):  
Optical Lattice ◽  
Service Center ◽  
Time Service ◽  
Optical Lattice Clock

Closed-Loop Operation of Optical Lattice Clock at National Time Service Center

2018 ◽  
Author(s):  
Xu Qin-Fang ◽  
Yin Mo-Juan ◽  
Wang Ye-Bing ◽  
Ren Jie ◽  
Guo Yang ◽  
...  
Keyword(s):  
Optical Lattice ◽  
Closed Loop ◽  
Service Center ◽  
Time Service ◽  
Optical Lattice Clock

scholarly journals Demonstration of the Systematic Evaluation of an Optical Lattice Clock Using the Drift-Insensitive Self-Comparison Method

2021 ◽  
Vol 11 (3) ◽  
pp. 1206
Author(s):  
Chihua Zhou ◽  
Xiaotong Lu ◽  
Benquan Lu ◽  
Yebing Wang ◽  
Hong Chang
Keyword(s):  
Optical Lattice ◽  
Laser Frequency ◽  
Frequency Offset ◽  
Comparison Method ◽  
Second Order ◽  
Systematic Evaluation ◽  
Zeeman Shift ◽  
Optical Lattice Clock ◽  
Incorrect Measurement ◽  
Comparison Technique

The self-comparison method is a powerful tool in the uncertainty evaluation of optical lattice clocks, but any drifts will cause a frequency offset between the two compared clock loops and thus lead to incorrect measurement result. We propose a drift-insensitive self-comparison method to remove this frequency offset by adjusting the clock detection sequence. We also experimentally demonstrate the validity of this method in a one-dimensional 87Sr optical lattice clock. As the clock laser frequency drift exists, the measured frequency difference between two identical clock loops is (240 ± 34) mHz using the traditional self-comparison method, while it is (−15 ± 16) mHz using the drift-insensitive self-comparison method, indicating that this frequency offset is cancelled within current measurement precision. We further use the drift-insensitive self-comparison technique to measure the collisional shift and the second-order Zeeman shift of our clock and the results show that the fractional collisional shift and the second-order Zeeman shift are 4.54(28) × 10−16 and 5.06(3) × 10−17, respectively.

scholarly journals Figures of merit for stellarators near the magnetic axis

2021 ◽  
Vol 87 (1) ◽  
Author(s):  
Matt Landreman
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Axis ◽  
Configuration Design ◽  
New Paradigm ◽  
First Order ◽  
Figures Of Merit ◽  
Minor Radius ◽  
Error Field ◽  
Quantities Of Interest

A new paradigm for rapid stellarator configuration design has been recently demonstrated, in which the shapes of quasisymmetric or omnigenous flux surfaces are computed directly using an expansion in small distance from the magnetic axis. To further develop this approach, here we derive several other quantities of interest that can be rapidly computed from this near-axis expansion. First, the $\boldsymbol {\nabla }\boldsymbol {B}$ and $\boldsymbol {\nabla }\boldsymbol {\nabla }\boldsymbol {B}$ tensors are computed, which can be used for direct derivative-based optimization of electromagnetic coil shapes to achieve the desired magnetic configuration. Moreover, if the norm of these tensors is large compared with the field strength for a given magnetic field, the field must have a short length scale, suggesting it may be hard to produce with coils that are suitably far away. Second, we evaluate the minor radius at which the flux surface shapes would become singular, providing a lower bound on the achievable aspect ratio. This bound is also shown to be related to an equilibrium beta limit. Finally, for configurations that are constructed to achieve a desired magnetic field strength to first order in the expansion, we compute the error field that arises due to second-order terms.

Analytical solution for unsteady flow behind ionizing shock wave in a rotational axisymmetric non-ideal gas with azimuthal or axial magnetic field

2021 ◽  
Vol 76 (3) ◽  
pp. 265-283
Author(s):  
G. Nath
Keyword(s):  
Magnetic Field ◽  
Shock Wave ◽  
Analytical Solution ◽  
Axial Magnetic Field ◽  
Order Approximation ◽  
Ideal Gas ◽  
Field Region ◽  
First Order ◽  
First Order Approximation ◽  
Flow Variables

Abstract The approximate analytical solution for the propagation of gas ionizing cylindrical blast (shock) wave in a rotational axisymmetric non-ideal gas with azimuthal or axial magnetic field is investigated. The axial and azimuthal components of fluid velocity are taken into consideration and these flow variables, magnetic field in the ambient medium are assumed to be varying according to the power laws with distance from the axis of symmetry. The shock is supposed to be strong one for the ratio C 0 V s 2 ${\left(\frac{{C}_{0}}{{V}_{s}}\right)}^{2}$ to be a negligible small quantity, where C 0 is the sound velocity in undisturbed fluid and V S is the shock velocity. In the undisturbed medium the density is assumed to be constant to obtain the similarity solution. The flow variables in power series of C 0 V s 2 ${\left(\frac{{C}_{0}}{{V}_{s}}\right)}^{2}$ are expanded to obtain the approximate analytical solutions. The first order and second order approximations to the solutions are discussed with the help of power series expansion. For the first order approximation the analytical solutions are derived. In the flow-field region behind the blast wave the distribution of the flow variables in the case of first order approximation is shown in graphs. It is observed that in the flow field region the quantity J 0 increases with an increase in the value of gas non-idealness parameter or Alfven-Mach number or rotational parameter. Hence, the non-idealness of the gas and the presence of rotation or magnetic field have decaying effect on shock wave.

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