Laser control of degenerate system by stimulated Raman adiabatic passage

The stimulated Raman adiabatic passage (STIRAP) is an effective and robust method to control the chemical reaction by means of the laser pulses, which generate the quantum coherence in molecular states. The STIRAP, however, is usually not applicable to the molecular system with two degenerate states such as optical isomers. We propose here a different strategy within the STIRAP, which generates the effective transition from one isomer to the other, and apply this method to the model system with two degenerate levels.