2013-10-23
11:15 at HCI J 574

Electromagnetically induced transparency and its description through quantum master equations including the non-linear thermodynamic one

Vlasis Mavrantzas

Polymer Physics, Department of Materials, ETH Zurich

In this seminar, our focus will be on the phenomenon of the electromagnetically induced transparency (EIT) and its description through quantum master equations. The EIT is achievable only in atoms with specific energy structures. For, example, for a three level system (to which the present study has focused), EIT requires two dipole allowed transitions (the 1-3 and the 2-3) and one forbidden (the 1-3). The phenomenon is observed when a strong laser (termed the control laser) is tuned to the resonant frequency of the upper two levels. Then, as a weak probe laser is scanned in frequency across the other transition, the medium is observed to exhibit both: a) transparency at what was the maximal absorption in the absence of the coupling field, and b) large dispersion effects at the atomic resonance. We will derive the Hamiltonian describing the phenomenon and we will present results from three types of master equations: a) an empirically modified von Newmann allowing for decays from each energy state, b) a typical Lindblad, and c) the recently proposed non-linear thermodynamic quantum master equation. In cases (a) and (b), analytical results are possible under certain approximations, which have been confirmed through a direct solution of the full master equation. In case of the non-linear (thermodynamic) quantum master equation, only numerical results have been possible. We will discuss these, especially in comparison with those of the modified von Newmann and the Lindblad ones.