[Phys-seminars] 2017-11-15 Condensed Matter Theory Seminar

smoshe smoshe at bgu.ac.il
Mon Nov 13 12:54:14 IST 2017


Condensed Matter Theory Seminar

 DATE: 15-11-17

 TIME: 13:30

 PLACE: Physics building (#54) room 207

TITLE: 
Energy Transfer in The Presence of Correlated and Uncorrelated Phonons

SPEAKER: 
Omer Goldberg, Ben Gurion University

ABSTRACT/COMMENTS: 
The transport properties of nanoscale systems can be strongly affected - even determined - by the interaction between the transported particles and the vibrations of the system. An important example is photosynthetic networks in which excitons, generated by sunlight, are transferred from one chromophores to another. The interaction of these excitons with local vibrations is presumed to play a crucial role in the dynamics of the system. We study the role vibrations play in the energy transfer through the simplest possible transfer network – only two chromophores long, where each chromophore is modeled by a non-interacting quantum level, coupled to vibrations. By using a non-equilibrium Green’s functions technique for the full exciton-vibration system, we can treat the strong exciton-vibration coupling regime. In particular, we compare between cases where the vibrations of each quantum level are either correlated (global vibrations) or uncorrelated (local). We find that the
  two cases exhibit qualitatively different energy transfer properties. For global vibrations, the energy current shows anti- resonances, which are due to interference between states with different polaron number. Counter-intuitively, this interference feature increases with increasing temperature. When the vibrations are uncorrelated, the dominant feature is resonant exciton tunneling, which is totally absent for the correlated case.


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