Dynamic Modeling And Simulation Of Alkali Metal Spin Polarization Ensemble

In recent years,in the field of precision measurement,the technique of using the spin polarization process of the alkali metal atomic system has been developed rapidly.This process has been used to detect various physical quantities,such as magnetic field,angular velocity and frequency.Moreover,magnetic field measurement technology has also ushered in a period of rapid development,and has been widely used in the fields of earth science,medicine,national defense and military and basic physics.In order to achieve higher measurement sensitivity and measurement bandwidth by using the spin of alkali metal atomic ensemble to magnetic field,it is necessary to constantly optimize the parameters of spin ensemble.Therefore,it is of great significance to study the dynamic evolution process of an atomic spin ensemble.This paper firstly introduces the dynamic evolution of spin polarized alkali metal atoms in magnetic field from the aspects of energy level structure of alkali metal atoms,optical pumping process and Larmor precession of spin assembly in magnetic field.Then,starting with the classical Bloch equation,the spin evolution processes of several typical alkali metal atomic magnetometers are mathematically derived and analyzed,including radio frequency magnetometers,Bell-Bloom magnetometers,and parametric oscillatory magnetometers.On the basis of theoretical analysis,a mathematical model of the spin dynamics process in an alkali metal atomic magnetometer was established using Simulink software.The core of the model is Bloch equation module,which can describe the spin precession process of alkali metal atomic system under the action of external magnetic field with time.At present,the quantum measurement of magnetic field is in the stage from the quantum control physics research of basic atomic spin to the application of magnetic field precision measurement technology scheme and measurement index optimization.We have used Matlab App Designer to develop a simulation software for precision magnetic field measurement system based on alkali metal spin polarisation.This software contains six main modules,including simulation models for common alkali metal atomic magnetometers.For physical research,the software provides a convenient tool for researchers to complete the analysis of parameter optimisation solutions for magnetic measurement systems,and builds a bridge from the basic principles of quantum science to engineering solutions for precision magnetic field measurement.As for the technical aspect,this paper introduces the physical modeling process and software development and compilation process based on Matlab App Designer in detail,to provide certain ideas and help for the same type of software development.Finally,using simulation software,we designed some experiments to study the physical processes of spin dynamics in alkali metal spin polarization systems.Through the analysis of experimental results and images,the correctness of the established model was verified.The dynamic process of spin polarization ensemble is deeply understood from both theoretical and simulation perspectives.In order to improve the measurement sensitivity and measurement bandwidth for magnetic fields,we have combined theory and simulation to study the spin dynamics process in alkali metal spin polarization systems.It lays a foundation for the specific analysis of various parameters and noise analysis in the magnetic field measurement process.Provide some help for completing the parameter optimization of the magnetic field measurement system.