随时间变化磁场中自旋演化的求解新方法

A New Approach to Spin Evolution in Time-Dependent Magnetic Field

采用粒子自旋角动量的两个独立谐振子实现和含时规范变换方法,得到不同空间位形的时变磁场中粒子的自旋态,并指出作旋转波近似,即忽略含时快变反共振项的物理原因。本文所用的新方法可应用于其它一些量子系统。

A spin particle subjected to time-dependent magnetic field is reseached in detail at different magnetic field configurations.A spin state is obtained easily by means of realizing two independent harmonic oscillators for spin angular momentum and a gauge transformation method,and physical reason for rotationless wave approximation,i.e.ignoring time-varying anti-resonant term is clarified.The approach can also be applicable in some other quantum systems.