Coherent transient effects of population blocking and population transfer in three-level media

Hui Sun, Hong Guo, Dongmei Deng +5 more

Klaas Bergmann, J. Martin, Bruce W. Shore

Olga Makarova, Sergey V. Prants

Novel coherent transient effects of population locking in driven three-level media are demonstrated theoretically. With the help of exact solutions of the evolution equation with the time-dependent Hamiltonian we `design' laser and rf fields to lock population under the conditions of nonstationary two- and tri-photon resonances.

Nikolay V. Vitanov, Stig Stenholm

B. D. Clader, Joseph H. Eberly

We analyze the effects of partial coherence of ground-state preparation on two-pulse propagation in a three-level $\ensuremath{\Lambda}$ medium, in contrast to previous treatments that have considered the cases of media whose ground states are characterized by probabilities (level populations) or by probability amplitudes (coherent pure states). We present analytic solutions of the Maxwell-Bloch equations, and we extend our analysis with numerical solutions to the same equations. We interpret these solutions in the bright and dark dressed-state basis, and show that they describe a population transfer between the bright and dark state. For mixed-state $\ensuremath{\Lambda}$ media with partial ground-state phase coherence the dark state can never be fully populated. This has implications for phase-coherent effects such as pulse matching, coherent population trapping, and electromagnetically induced transparency (EIT). We show that for partially phase-coherent three-level media, self-induced transparency dominates EIT and our results suggest a corresponding three-level area theorem.

Aleksandra Sierant, Marek Kopciuch, Szymon Pustelny

In this paper, we investigate the coherent control over a complex multilevel atomic system using the stimulated Raman adiabatic passage. Based on the example of $^{87}\mathrm{Rb}$ atoms, excited with circularly polarized light at the ${D}_{1}$ line, we demonstrate the ability to decompose the system into three- and four-level subsystems independently interacting with light beams. Focusing on the four-level system, we demonstrate that the presence of an additional excited state significantly affects the dynamics of the system evolution. Specifically, it is shown that, through the appropriate tuning of the light beams, some of the transfer channels can be blocked, which leads to better control over the system. We also demonstrate that this effect is most significant in media free from inhomogeneous broadening (e.g., Doppler effect) and deteriorates if such broadening is present. For instance, the motion of atoms affects both the efficiency and selectivity of the transfer.