Nonequilibrium Quantum Dynamics of Excitons in Photoactive Molecular Complexes
by
Michael Thorwart
→
Europe/Berlin
Seminar room 2 (DESY Hamburg)
Seminar room 2
DESY Hamburg
Description
The first steps of photosynthesis consist of the capture of a solar
photon by a biomolecular antenna complex and the formation of an
exciton. This excitation energy is transfered along a biomolecular
complex via dipolar Coulomb coupling until it reaches the reaction
center where this energy triggers a complicated series of chemical
reactions. Since the early days of quantum mechanics, this energy
transfer process has been considered as an incoherent hopping
described by a Fermi Golden Rule type rate constant ("Forster
transfer"). Recent experiments have challenged this orthodox view and
claimed the observation of long-lived quantum coherence over several
hundreds of femtoseconds - despite the presence of a "hot, wet and
dirty" bio-environment. I will discuss the approach to this nonequilibrium
problem within the theory of open quantum systems and show
that non-Markovian bath fluctuations induced by a polar solvent can
enhance the quantum coherence properties in damped quantum systems.