高频强场中Kramers-Henneberger变换在狄拉克方程中的应用

在强激光场中,通过Kramers-Henneberger(KH)变换和高频近似可以将狄拉克方程的求解从一个含时问题转换成一个稳态问题来研究。以氢原子为例,详细研究了相对论框架下该稳态问题中的有效库仑势的特点,并和非相对论框架下的结果进行了比较。研究发现,由于相对论有效质量的引入,有效库仑势的分布范围并不像非相对论条件下随着激光场强度的增强单调变大,而是增加到一定值后不再变化。另外,通过比较偶极近似和非偶极近似下有效库仑势的分布,发现对高频强场,偶极近似不再适用。

Application of Kramers-Henneberger transformation in Dirac equation under high-frequency intense laser fields

By using the Kramers-Henneberger (KH) transformation, the time-dependent Dirac equation in high-frequency (HF) intense laser fields can be changed to a time-independent equation with an effective Coulomb potential, which plays an important role in studying the adiabatic atomic stability problem in high-frequency laser fields. With numerical method, we have investigated in detail the characteristics of the obtained effective Coulomb potential. It has been found that when the laser intensity is high enough, the relativistic effect is so important that it modifies the effective potential drastically. Moreover, the dipole approximation, which is often used in literature when solving Schrodinger equation, is not proper for high-frequency laser fields.