原子自旋破坏碰撞弛豫对原子磁强计精度的影响

THE INFLUENCE OF SPIN-DESTRUCTION COLLISIONS ON THE PRECISION OF ATOMIC MAGNETOMETERS

磁强计是测量磁场的重要工具.实现高精度的磁场测量,无论对基础科学研究还是实际工程应用都具有重要的意义.在实际测量过程中,磁强计容易受到各种因素的干扰,使得其测量精度受到限制.文章主要研究原子自旋破坏碰撞弛豫对原子磁强计精度的影响.首先,综合考虑测量的后效效应以及原子系综内部由于原子自旋破坏碰撞导致的退极化效应,得到一个改进的量子随机主方程模型.其次,以该模型为基础,利用卡尔曼滤波方法对连续变化的极弱磁场进行估计.利用数值模拟将得到的估计表现与忽略原子自旋破坏碰撞作用下的结果进行了比较.数值模拟结果表明,原子自旋破坏碰撞导致的退极化效应会对原子磁强计精度产生非常显著的影响.

Magnetometers are important instruments for measuring magnetic fields. High precision measurement of magnetic fields has been of great importance for both fundamental physics and practical applications. In the process of practical measurement, the implementation of magnetometers is vulnerable to various kinds of disturbances, which will degrade the precision and sensitivity of magnetometers. In this paper, we mainly investigate the influence of spindestruction collisions between atoms on the precision of atomic magntometers. Taking into account both the back-action effect of the measurement and the depolarization effect caused by the spin-destruction collisions between atoms, we first get a modified stochastic master equation model. Based on this model, we then adopt the Kalman filter method to estimate an extremely weak magnetic field. We further compare the estimation performances with those that obtained when the spin-destruction collisions between atoms are ignored. Through numerical simulations, it is demonstrated that the relaxation due to the spin-destruction collisions has a significant impact on the sensitivity of atomic magnetometers.