We extend the idea of laser cooling with adiabatic passage to multi-level type-II transitions. We find the cooling force can be significantly enhanced when a proper magnetic field is applied. That is because the magnetic field decomposes the multi-level system into several two-level sub-systems, hence the stimulated absorption and stimulated emission can occur in order, allowing for the multiple photon momentum transfer. We show that this scheme also works on the laser-coolable molecules with a better cooling effect compared to the conventional Doppler cooling. A reduced dependence on spontaneous emission based on our scheme is observed as well. Our results suggest this scheme is very feasible for laser cooling of polar molecules.

我们将通过绝热通道进行激光冷却的想法扩展到了多级II型过渡。我们发现，如果施加适当的磁场，冷却力会大大提高。这是因为磁场将多级系统分解为几个两级子系统，因此可以依次发生受激吸收和受激发射，从而实现了多光子动量传递。我们表明，与传统的多普勒冷却相比，该方案还可以对激光可冷却分子起作用，具有更好的冷却效果。还观察到基于我们的方案对自发发射的依赖性降低。我们的结果表明，该方案对于激光冷却极性分子非常可行。