The fundamental role of quantized vibrations in coherent light harvesting by cryptophyte algae

TL;DR

This paper demonstrates that quantized vibrations play a crucial role in enhancing energy transfer efficiency and coherence in photosynthetic cryptophyte algae, especially through non-equilibrium dynamics and vibrational-electronic coupling.

Contribution

It reveals the fundamental importance of high-energy quantized vibrations and their non-equilibrium behavior in biological energy transfer, highlighting their role in coherent dynamics and energy distribution.

Findings

Vibrational-electronic coupling enables rapid, wide energy distribution.

Non-equilibrium vibrational dynamics cause ultrafast coherence beating.

Coherent excitonic dynamics help channel energy to specific sites.

Abstract

The influence of fast vibrations on energy transfer and conversion in natural molecular aggregates is an issue of central interest. This article shows the important role of high-energy quantized vibrations and their non-equilibrium dynamics for energy transfer in photosynthetic systems with highly localized excitonic states. We consider the cryptophyte antennae protein phycoerythrin 545 and show that coupling to quantized vibrations which are quasi-resonant with excitonic transitions is fundamental for biological function as it generates non-cascaded transport with rapid and wider spatial distribution of excitation energy. Our work also indicates that the non-equilibrium dynamics of such vibrations can manifest itself in ultrafast beating of both excitonic populations and coherences at room temperature, with time scales in agreement with those reported in experiments. Moreover, we show that mechanisms supporting coherent excitonic dynamics assist coupling to selected modes that channel energy to preferential sites in the complex. We therefore argue that, in the presence of strong coupling between electronic excitations and quantized vibrations, a concrete and important advantage of quantum coherent dynamics is precisely to tune resonances that promote fast and effective energy distribution.