  The dynamics of excitonic energy transfer in molecular complexes triggered by
interaction with laser pulses offers a unique window into the underlying
physical processes. The absorbed energy moves through the network of
interlinked pigments and in photosynthetic complexes reaches a reaction center.
The efficiency and time-scale depend not only on the excitonic couplings, but
are also affected by the dissipation of energy to vibrational modes of the
molecules. An open quantum system description provides a suitable tool to
describe the involved processes and connects the decoherence and relaxation
dynamics to measurements of the time-dependent polarization.
