Prof. Janez Bonča: Study of polaron dynamics under the influence of a constant electric field

Pred predavanjem vse udeležence vabimo na čaj!

Povzetek:

       Study  of  polaron dynamics under the influence of  a constant electric field 

     Prof. Janez Bonča, Univerza v Ljubljani, Fakulteta za matematiko in fiziko & Institut Jožef Stefan

Research in the field of   non-equilibrium dynamics of complex quantum systems constitutes a formidable theoretical challenge.  Deep understanding of non-equilibrium effects is essential for further development of various experimental techniques like  ultrafast optic spectroscopy, measuring  transport through nanostructures, analysis of time-resolved measurements  in optical lattices, and  probing  polaron dynamics of conjugated polymer chains, just to name a few.

I will present a fundamental  study  of   an electron, coupled to inelastic bosonic degrees of freedom, described by the Holstein model in one dimension driven away from the equilibrium by a constant electric field. In the introduction I will review the  Landau-Zener tunneling within a two level system. We will then follow the time-evolution  of the Holstein polaron  from its   ground state as the constant electric field is switched on at t=0, until the system reaches  a steady state,  taking fully into account quantum effects.

At small electron phonon coupling (EP) the Holstein polaron experiences damped Bloch oscillations (BO) characteristic for a free electron band.  I will  explore  the shape of the phonon tail that forms behind the traveling polaron. The average phonon occupancy in the tail is given by the ratio of the electric field and the phonon frequency and is independent of the strength of the  EP interaction.