Optimal Control of Population Transfer in Three-Level Λ System with Genetic Algorithms

Population transfer in a three-level Λ system is simulated numerically and optimized. Almost complete population transfer from |1> to |3> is achieved by a genetic algorithm while the population in state |2> reached minimum over the entire evolution at the same time. The result shows that the optimal pulse sequence is the well-known stimulated Raman adiabatic passage (STIRAP) scheme. The detuning of pump pulse and Stokes pulse Δ_p and Δ_s with the opposite sign and the chirps x_p and x_s with the same sign are in favour of the complete and robust population transfer for few-cycle laser pulse. Rabi frequencies Ω_p and Ω_s have insensitive effects on the complete population transfer during a large scope of their ratio when they are large enough.