Coherent population trapping in a specific model

Coherent population trapping is shown to occur in a driven symmetric double-well potential. In the model of the ammonia molecule, for a molecule initially prepared in its lower doublet, under certain circumstances, the upper level remains unpopulated, this occurs in spite of the fact that the laser field is resonant with the |2〉→|3〉 trasition. This is a coherent population trapping phenomenon which cannot be accounted for with the convential models.