二能级原子与光场相互作用模型的流方程解法

利用Wegner流方程方法在平均场近似下研究了二能级原子与光场相互作用系统的本征值与本征函数。由于在幺正变换下产生了新的高阶相互作用项,利用平均场近似手段得到了系统参数随流参数变化的流方程。当具有哈密顿量H(l)的流参数l→∞时,系统中的耦合项参数趋于0,非耦合项参数趋于稳定值。最后,利用流方程方法求出了原子自旋的关联函数。

Flow equations for light field interacting with two-level atoms

We apply Wegner's flow equation method to study the eigenvalue of two-level atom system acted by light field.Interactions not contained in the original Hamiltonian are generated by this unitary transformation.With an average field approximation,we can close the flow equations.In the flow parameter l→∞ limit with Hamiltonian H(l),the interaction terms vanish and noninteraction terms approach fixed values.In the end,we obtain an explicit expression of the spin atom autocorrelation function.