Study of nonlinear effects in a spin-orbit mixed five-level molecular system coupled by three lasers

We study the nonlinear effect in a spin-orbit mixed five-level molecular system coupled by three lasers. The spin-orbit mixed rovibrational levels carry both characteristics of the singlet and triplet states depending on the degree of mixing. The mixing coefficient of the mixed states varies from case to case. However, when the mixed states are coupled to auxiliary quantum states with lasers, the mixing coefficient of the singlet-triplet states can be modified by ac Stark effect via controlling the Rabi frequency, and the frequency detuning of the coupling lasers. We use density matrix equations in a five-level molecular model to show the nonlinear effects in a mixed singlet-triplet pair of rovibrational levels, and the quantum control the mixing of the states to enhance the access to the target quantum states.