2014-06-11
11:00 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

We will discuss the phenomenon of the electromagnetically induced transparency (EIT) and its description through quantum master equations. EIT is achievable only in atoms with specific energy structures: e.g., for a 3-level system (to which the present study has focused), it 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 (control laser) is tuned to the resonant frequency of the upper two levels. And 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 present numerical and in some cases analytical results from three types of master equations: a) an empirically modified von Newmann allowing for decays from each energy state, b) a typical Lindblad with time-dependent operators, and c) the recently proposed non-linear thermodynamic quantum master equation. We will discuss advantages and disadvantages of the three methods, in particular in their capability to describe the temperature dependence of the phenomenon. In cases (2) and (3) we will also see how the friction coefficient (a measure of the coupling with the environment) affects the phenomenon.