We investigate the effect of chirped excitation and the excitation detuning on the coherent control of population transfer and vibrational states in a four---level system. Density matrix equations are studied for optimally enhanced processes by considering specific parameters typical of oxazine systems. Our simulations show a strong dependence on the interplay between chirp and excitation detuning and predict enhancement factors up to 3.2 for population transfer and up to
38.5 for vibrational coherences of electronic excited states. The study of the dynamics of the populations and vibrational coherences involved in the four---level system allows an interpretation of the different enhancement/suppression processes observed.
We present a numerical solution for complete population inversion in a four-level ladder system obtained by using a full p-pulse illumination scheme with resonant ultrashort phase-locked Gaussian laser pulses. We find that a set of pulse areas such as v3p , v2p , and v3p completely inverts the four-level system considering identical effective dipole coupling coefficients. The solution is consistent provided the involved electric fields are not too strong and it is amply accurate also in the case of diverse transition dipole moments. We study the effect of detuning and chirp of the laser pulses on the complete population inversion using the level structure of atomic sodium interacting with ps and fs pulses as an example. Our result opens the door for multiple applications such as efficient ultrashort pulse lasing in the UV or the engineering of quantum states for quantum computing.
Brühl, E.; Afa, I.J.; Serrat, C.; Buckup, T.; Motzkus, M. DPG Spring Meeting of the Atomic, Molecular, Plasma Physics and Quantum Optics Section p. 1- Data de presentació: 2015-03-23 Presentació treball a congrés