Indicators of quantum coherence in light-harvesting dynamics

Characterizing quantum dynamics of electronic excitations in a variety of light-harvesting systems is currently of much interest [1]. In particular, it is important to identify measures that appropriately quantify the strength of coherent dynamics and its impact on different time scales of the light-harvesting process. In this talk I will discuss quantum transport performance measures that are defined based on the probability for the dynamics to successfully distinguish different initial photo-excitation conditions. I will also discuss how initial state distinguisability can provide information on spatially correlated phonon fluctuations as well as on the non-markovian character of the quantum dynamics. The prototype systems considered here are cryptophyte light-harvesting antennae isolated from marine algae [2, 3]. Experimental quantification of state distinguishability can be realized by monitoring the evolution of selected off-diagonal density matrix elements and therefore it could be achieved with current two-dimensional spectroscopy techniques. \\[4pt] [1] A. Olaya-Castro and G. D. Scholes, ``Energy transfer from F\"{o}rster-Dexter theory to quantum coherent light-harvesting'', to appear in Int. Rev. Phys. Chem. (2010) \\[0pt] [2] E. Collini, C.Y. Wong, K.E. Wilk, P.M.G. Curmi, P. Brumer and G.D. Scholes, ``Coherently wired light-harvesting in photosynthetic marine algae at ambient temperature'' Nature, 463, 644-647 (2010) \\[0pt] [3] A. Kolli, A Nazir, F. Fassioli, R. Dinshaw, G D Scholes, and A Olaya-Castro, ``Energy transfer dynamics in cryptophyte antennae proteins'', submitted for publication (2010)