  The Fenna-Matthews-Olson (FMO) complex - a pigment protein complex involved
in photosynthesis in green sulfur bacteria - is remarkably efficient in
transferring excitation energy from light harvesting antenna molecules to a
reaction center. Recent experimental and theoretical studies suggest that
quantum coherence and entanglement may play a role in this excitation energy
transfer (EET). We examine whether bipartite quantum nonlocality, a property
that expresses a stronger-than-entanglement form of correlation, exists between
different pairs of chromophores in the FMO complex when modeling the EET by the
hierarchically coupled equations of motion method. We compare the results for
nonlocality with the amount of bipartite entanglement in the system. In
particular, we analyze in what way these correlation properties are affected by
different initial conditions. It is found that bipartite nonlocality only
exists when the initial conditions are chosen in an unphysiological manner and
probably is absent when considering the EET in the FMO complex in its natural
habitat. It is also seen that nonlocality and entanglement behave quite
differently in this system. In particular, for localized initial states,
nonlocality only exists on a very short time scale and then drops to zero in an
abrupt manner. As already known from previous studies, quantum entanglement
between chromophore pairs on the other hand is oscillating and exponentially
decaying and follow thereby a pattern more similar to the chromophore
population dynamics. The abrupt disappearance of nonlocality in the presence of
nonvanishing entanglement is a phenomenon we call nonlocality sudden death; a
striking manifestation of the difference between these two types of
correlations in quantum systems.
