CPT磁力仪暗态耦合磁场测量技术

摘要

相干粒子数俘获(CPT)磁力仪是通过精确追踪光与原子相互作用下获得的透射信号来计算磁场强度的.针对由于透射信号的方向性衰减特性而造成的系统测量盲区的问题,提出了一种暗态耦合测量方案,通过使用特定频率的调制光场来实现多个暗态的同时激发和耦合测量,基于原子密度矩阵法建立了原子五能级系统模型并进行数值仿真研究,分析了该方案的控制条件和特点.实验结果证明,使用暗态耦合测量技术获得的透射信号幅值可以达到相同条件下单暗态测量时信号幅值的两倍左右,能够有效消除测量盲区,提高透射信号的信噪比,从而进一步提高CPT磁力仪的测量灵敏度.%Coherent population trapping (CPT) magnetometer calculates the magnetic field strength by precisely tracking the transmitted signal obtained by the interaction of light and atoms. A dark state coupling measurement scheme is proposed for the system's measurement blind area caused by the directional attenuation of the transmitted signal. The simultaneous excitation and the coupling measurements of multiple dark states are achieved by using modulated light fields with specific frequency. Based on the atomic density matrix method, an atomic five-level system model is established, and the numerical simulation is performed. The control conditions and characteristics of the scheme are analyzed. The experimental results show that the amplitude of transmitted signal obtained by dark coupling measurement can reach about two times of the amplitude of single dark state measurement under the same condition. This scheme can effectively eliminate the measurement blind area, improve the signal-to-noise ratio of the transmitted signal, and further improve the measurement sensitivity of the CPT magnetometer.