Apr 5,
2010
4:15p - 5:15p
Two-Dimensional Electronic Spectroscopy: Coherence, Entanglement
and Photosynthesis
Graham Fleming, University of California, Berkeley
Jefferson 250
Tea served in Jefferson 450 @ 3:30 pm
Description Two-dimensional (2D) electronic spectra contain
information about the combined spatial, energetic and temporal
landscapes of condensed phase systems. Because they are recorded
at the amplitude level, they are directly sensitive to the
presence of quantum coherence. In addition, differing sequences
of polarizations of the four fields involved can suppress or
enhance specific features in the spectra. An example is given by
a sequence which reveals only peaks that have arisen through
coherence transfer as opposed to population transfer. In this
talk these ideas will be applied to natural photosynthetic light
harvesting systems. These pigment-protein complexes contain
chlorophyll molecules at very high spatial density, leading to
delocalized excited states. The experiments reveal long-lived
quantum electronic coherence and substantial coherence transfer
leading to speculations about the physiological consequences of
quantum effects, and the potential applications in quantum
theory. New theoretical methods are required to address these
questions and a formally exact, reduced hierarchy approach will
be used to describe the experiments and explore more subtle
quantum mechanical questions such as the presence of entanglement
in natural systems.
Web site:
www.physics.harvard.edu <http://www.physics.harvard.edu>
Contact name: Dayle Maynard
Contact e-mail: maynard(a)physics.harvard.edu
<mailto:maynard@physics.harvard.edu>
Contact phone: 617.495.2872
Source Calendar: Physics Monday Colloquia