Quantum effects in the efficiency of Fenna-Matthews-Olson light-harvesting complexes

Abstract

Renewable energy continues to be the fastest growing industry among the power sector, the same is true for the development of quantum computing for data analysis. There is a stretch relationship between these two branches of research being brought together by yet another branch of science: biology. Biological light-harvesting complexes (LHCs) involved in the photosynthetic process present energy transfer efficiencies of almost 100\%, providing a source of inspiration for the development new technologies that could mimic these characteristics. One of the most extensively studied LHCs is the Fenna-Matthews-Olson (FMO) complex. This work is focused on the development of a comprehensible model of excitation energy transfer dynamics in the FMO light-harvesting complex. Considering the research branches involved in this study and the different perspectives from which this complex has been analysed, this work will be taking into account some biological considerations at the molecular, genetic and organism levels to avoid unsubstantiated assumptions. The presence of quantum coherence between electronic states of the bacteriochlorophylls concealed inside the FMO complex during the photosynthetic process of green sulfur bacteria has inspired researchers to attempt computer simulations to understand its complexity. Although several methods have been explored to model this quantum phenomenon in the domains of open quantum systems, the traditional methods used do not take into account the memory effects of the surroundings, which is commonly approximated as a phonon bath on thermal equilibrium. A popular solution to overcome this limitation is the application of the hierarchical equations of motion (HEOM) method, a non-Markovian approach also used to analyze the dynamics of such a complex, for the modeling of the system evolution. The proposed variation of the parameters that govern the HEOM method in this study provides a new form of characterization for the FMO system. A parametric analysis of some physical features involved during the excitation energy transfer process is performed to better understand its non-trivial dependence on operation parameters in the quantum realm. The analysis is conducted in terms of the parameters of temperature, relocation energy, and dephasing rate in the system to track the complex global behavior of coherence, entanglement, decoherence times, transference times, and efficiency of the main process of energy transfer. Complementarily, a comparison between two different species is made as a suggestive possible road map to track genetic differences in the photosynthetic performance of the complex through its biological nature.