Distribution of entanglement in light-harvesting complexes and their quantum efficiency

Abstract

Recent evidence of electronic coherence during energy transfer in photosynthetic antenna complexes has reinvigorated the discussion of whether coherence and/or entanglement has any practical functionality for these molecular systems. Here we investigate quantitative relationships between the quantum yield of a light-harvesting complex and the distribution of entanglement among its components. Our study focusses on the entanglement yield or average entanglement surviving a time scale comparable to the average excitation trapping time. As a prototype system we consider the Fenna-Matthews-Olson (FMO) protein of green sulphur bacteria and show that there is an inverse relationship between the quantum efficiency and the average entanglement between distant donor sites. Our results suggest that longlasting electronic coherence among distant donors might help modulation of the lightharvesting function.

Enhanced resonant force between two entangled identical atoms in a photonic crystal

“…In order to obtain the interaction energy between the two atoms in the isotropic crystal, as a function of their distance, and then the force in the quasi-static approach, we need to solve Eq. (14), where the function ω k /(z− ω k ) should be considered as a principal part. In Eq.…”

“…We shall therefore neglect them compared to modes just above the gap. All these considerations allow us to use k 0 and ∞ as, respectively, lower and upper limit of integration in (14), and to use the effective mass approximation (24). The fact that in this way we are also including modes with wavevector k well above k 0 , for which the effective mass approximation is not valid, does not introduce a significant error because they give a small contribution to the integral, due to the low density of states and/or the off-resonance condition for these field modes.…”

“…Resonant interactions occur when one or more molecules are in their excited state and the interaction, being involved the exchange of real photons between the atoms, can be of very long range [6][7][8][9][10]. The resonant interatomic force is also related to the resonant energy transfer between molecules [11], which has been recently guessed to play a role in coherent biological phenomena such as photosynthesis [12][13][14] or interactions between macromolecules [15].…”

Electronic excitation dynamics in multichromophoric systems described via a polaron-representation master equation

“…This approach has been used to provide insights into the effects of coherence in spectroscopic signals 28,29 and more recently to understand the roles of coherence and relaxation in the efficiency of excitation transfer. [30][31][32][33][34][35][36][37][38] However, many multichromophoric systems operate in an intermediate regime where exciton, vibronic relaxation, and exciton-phonon coupling energy scales are comparable and hence traditional perturbative treatments become inaccurate. This has lead to recent investigation of excitation dynamics using non-perturbative approaches 39,40,[42][43][44][45][46] and sophisticated stochastic treatments 47 of the system-plusbath dynamics.…”

Heat transport between two pure-dephasing reservoirs

“…For models of photosynthetic molecules [8], h is the energy difference between two chromophores and ∆ is the excitonic coupling between them. The model can also describe the single-excitation subspace of a chain of coupled spins [10].…”