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 Karl Franzens University Graz

Graz University of Technology 

Analysis and control of electronic motion on the femto-second time scale
Prof. E. K. U. Gross
MPI Halle, Germany
17:15 - 18:15 Tuesday 05 November 2013 TUG P2

In this lecture, the time-dependent generalization of density functional theory will be employed to visualize, analyse and, ultimately, control electronic motion on the femto-second time scale. Several recent developments beyond the linear-response regime will be presented. One of them is the time-dependent electron localization function (ELF). This quantity allows one to visualize the formation and breaking of chemical bonds in a laser field in real time. The sequence of snapshots below shows a laser-induced π-π* transition in acetylene. Questions like: “How much time needs an electron to complete a transition from one state to another? “ can be addressed in this way.

The second main topic will be quantum transport. Time-dependent features of the electronic current through nano-scale junctions will be studied such as electron pumps and molecular optical switches. In particular, a time-dependent picture of Coulomb blockade will be drawn which corresponds to a periodic charging and discharging of the junction. Finally, quantum optimal control theory will be presented as a method to compute laser pulses that are optimized to achieve a given goal. As an example we will calculate the laser pulse needed to switch the chirality of the electronic current in a quantum ring.