Environment-assisted quantum transport
This figure presents a version of our results in reference [1] for the Fenna-Matthews-Olson complex of P. aestuarii. New data [2] and the pure-dephasing model of [1] were used for the simulation of the exciton dynamics.
The figure shows a more dramatic ENAQT effect for the efficiency (blue curve) at weak dephasing rates. This is explained by the energy landscape of the new Hamiltonian [2], which in the fully coherent case leads the exciton to become stuck close to the initial site. In both old and new figure, the transfer time (purple curve) is more sensitive to the environment than the efficiency. It should make a considerable difference for the biological organism if, on average, the exciton takes 20 ps instead of ~5 ps to travel through this complex.
In general, it certainly has to do with the simplicity of the pure-dephasing model that a wide range of the dephasing rate has to be scanned for interesting things to happen. More detailed quantum chemistry work is in progress by our group [3] and others.
[1] Patrick Rebentrost, Masoud Mohseni, Ivan Kassal, Seth Lloyd, Alán Aspuru-Guzik, Environment-Assisted Quantum Transport, New Journal of Physics 11, 033003 (2009).
[2] Marcel Schmidt am Busch, Frank Müh, Mohamed El-Amine Madjet, Thomas Renger, The Eighth Bacteriochlorophyll Completes the Excitation Energy Funnel in the FMO Protein, Journal of Physical Chemistry Letters 2, 93 (2011).
[3] Sangwoo Shim, Patrick Rebentrost, Stéphanie Valleau, Alán Aspuru-Guzik, Microscopic study of the long-lived quantum coherences in the Fenna-Matthews-Olson complex, Preprint: arXiv:1104.2943 (2011).