量子频标研究室知识库

The frequency shift caused by blackbody radiation is one of the dominant corrections to the evaluation of the optical lattice clock. The frequency shift of blackbody radiation is closely related to the dynamic and static correction factor, ambient temperature and atomic polarizability. The blackbody radiation shift is mainly affected by ambient temperature. During the normal operation of the strontium atom optical lattice clock, the experimental environment and other heat sources around the vacuum cavity have complicated the environment around the vacuum cavity, resulting in the fact that the external surface temperature of the vacuum cavity does not truly reflect the temperature change of the vacuum cavity. For the strontium atomic optical clock experimental apparatus of the National Time Service Center, the uncertainty and correction of the blackbody radiation frequency shift are evaluated by the theoretical analysis, measurement of the temperature of the vacuum cavity outer surface, and software simulation. Among them, the frequency shift of black body radiation caused by strontium atom furnace, sapphire heating window, room temperature radiation entering into the vacuum cavity through the window plate, and the thermal radiation at the atomic group caused by Zeeman reducer are analyzed. Five temperature measuring points are set on the external surface of the vacuum chamber, and the temperature changes on the external surface of the vacuum chamber are monitored in real time by using the calibrated platinum resistance temperature sensor while the system is running normally. We obtain the average temperature of the five temperature measuring points. The model of vacuum cavity is established by using the SolidWorks. The method of finite element analysis is used to simulate the variation of the temperature around atom samples. We also obtain the temperature distribution around the atomic groups in the vacuum cavity. The result shows that the temperature around atoms varies with the temperature of the vacuum cavity. When the temperature of the ambient temperature changes 0.72 K, the fluctuation of the temperature around the atoms is 0.34 K. Finally, the total correction of blackbody radiation of the system is evaluated to be -2.13(1) Hz, and the correction uncertainty is about 2.4 x 10(-17).