Dresden 2009 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 23: Transport: Nanoelectronics III - Molecular Electronics

TT 23.8: Vortrag

Mittwoch, 25. März 2009, 11:30–11:45, HSZ 105

Entangled excitation dynamics in biomolecules due to spatially correlated environmental fluctuations — •Peter Nalbach and Michael Thorwart — Freiburg Institute for Advanced Studies, Albert-Ludwigs Universität Freiburg, Albertstr. 19, 79104 Freiburg

In photosynthetic light harvesting complexes, absorbed photons induce excitations of biomolecular chromophores. The excitation moves until it reaches the reaction center where it transfers its energy to chemical reaction energy. A single excitation in two chromophores can be described by a quantum two level system (TLS) where the chromophore coupling is of Förster-type and is described as tunnelling between the two sites. In order to compare the energy transferred to a reaction center with the loss to the environment (formed by vibrational and rotational states of the molecular complexes or charge fluctuations in the solvent-protein host), a coupling of the TLS to an environment is introduced. The environment is characterized by a rather small reorganization energy, leading to slow bath-induced fluctuations. We investigate two coupled TLSs and show that quantum coherent energy transfer is efficiently supported by a slow (non-Markovian) bath which has spatial correlations extending over distances larger than the biomolecule distance. We discuss the inter-chromophore coupling generated by the slow bath modes which couple to both TLSs, its dependence on spatial distance and its influence on the coherent dynamics of the excitations.