Closed-loop Locking Of Magnesium-Aluminum Ion Optical Clock

Atomic clock is the most accurate equipment.It provides time reference for international atomic time.According to the different frequency bands of clocks,atomic clocks can be divided into microwave clocks and optical clocks.In order to build a highprecision time-frequency standard system,our group is conducting research on magnesiumaluminum ion optical clocks based on quantum logic technology.By completing the design of ion trapping system,optical system and control system,we built aluminum ion optical clock experimental platforms,and successfully detected quantum logic transition signal and clock transition signal.In this context,this thesis focus on the research related to optical clock closed-loop locking and stability optimization,and the main works are as follows:1.The theoretical calculation of the noise contribution terms that affect the stability of the optical clock has been completed,and it is found that the quantum projection noise limit of the current magnesium-aluminum ion optical clock is 4.5 × 10-15/(?),the Dick effect limit of ultra-stable laser is 4.6×10-16/(?).A closed-loop locking scheme based on "four-point locking" is proposed.2.Through the modeling and simulation analysis,a solution design for optimizing the stability of the magnesium-aluminum ion optical clock is proposed from the two aspects of reducing the Dick effect and the quantum projection noise.The results show that the alternative application of the first-order,second-order,and third-order Raman sideband cooling can improve the ion cooling efficiency,reduce the dead time,and achieve the purpose of suppressing the Dick effect.Through quantitative analysis of the relationship between the average number of vibrating phonons and the Rabi frequency,it is pointed out that the three-dimensional Raman sideband cooling can improve the signal-to-noise ratio of the quantum logic spectrum,improve the accuracy of the clock transition state judgment,and reduce the quantum projection noise.In order to realize three-dimensional Raman sideband cooling,the module upgrade and function optimization of parts of the experimental control system based on ARTIQ were completed,and a new control system with ns-level response time was obtained.3.The verification experiment of optical clock closed-loop locking principle is completed.It includes three aspects:closed-loop locking scheme design,program debug,and experimental realization.By means of two-point locking,the local oscillator frequency is locked to the ion clock transition spectrum.The results show that the stability of microwave resonant transition of 25Mg+ ion is 2.8×10-7/(?),and that of 3 P1 transition of 27Al+ion is 2.2×10-12/(?).The above work lays a foundation for the realization of linewidth narrowing and closed-loop locking of optical clock.