Magnetic-field-assisted stimulated laser cooling in the (1+3)-level atomic system

The theory of laser cooling assisted by transverse magnetic field Bt based on the (1+3)-level atomic system is presented. With the additional Bt, atoms could be redistributed among the upper Zeeman sublevels via Larmor precession, and results in large stimulated radiation force and low temperature. Here we consider this cooling model both for broad transition line and narrow line. A Fokker-Planck-type kinetic equation is derived for a broad line. Numerical result shows that the final temperature could be lower than the Doppler limit. For a narrow line, the Monte Carlo approach is applied to simulate the distribution of atoms in the momentum regime and the result shows that most atoms are distributed around zero velocity with width about several (ℎ/2π)k/m