The observation of coherent excited state dynamics in light-harvesting proteins [1-2] has given a new impetus to the long-standing discussion regarding relationships between energy transfer efficiency and non-trivial quantum features such as exciton delocalization (i.e. electronic coherence) [3-5]. In this work [5] we use the framework of entanglement to quantify the strength electronic coherences in a light- harvesting complex and investigate how such coherences are distributed among the molecular sites for different initial conditions and bath parameters. As a prototype system we consider the Fenna-Mathews-Olson (FMO) protein of green sulphur bacteria [1]. Our results suggest that long-lived electronic correlations between well-separated pigments provide a mechanism for controllably interfering two different energy transfer pathways in the FMO complex and therefore modulate the transfer efficiency when either the exciton-phonon coupling or temperature are varied.

References:

[1] Engel, G. S. , Calhoun, T. R. , Read, E. L. , Ahn, T.-K. , Mancal, T. , Cheng, Y.-C., Blankenship, R. E. , and Fleming, G.R. (2007) Nature 446, 782
[2] Collini, E. , Wong, C. Y., Wilk, K. E. , Curmi, P. M. G. , Brumer, P. and Scholes, G. D. (2010) Nature, 463, 644-647
[3] Olaya-Castro, A. , Lee, C. F., Fassioli, F., Johnson, N. F. (2008) Phys. Rev. B 78, 085115
[4] Fassioli, F., Nazir, A., Olaya-Castro, A. (2010) J. Phys. Chem. Lett. 1, 2139
[5] Fassioli, F. and Olaya-Castro, A. (2010) New J. Phys 12, 085006


Seminar, November 26, 2010, 12:00. Seminar Room

Hosted by Dr. Alejandra Valencia