Non-classicality of the molecular vibrations assisting exciton energy transfer at room temperature

TL;DR

This paper demonstrates that non-classical vibrational fluctuations in photosynthetic dimers can facilitate efficient energy transfer at room temperature, highlighting potential quantum effects in biological processes.

Contribution

It reveals that non-classical vibrational motions assist energy transfer in photosynthesis, induced by exciton-vibration interactions, and detectable via phase-space negativities.

Findings

Non-classical vibrational fluctuations are present at room temperature.

Quantum effects can be induced by incoherent excitation.

Non-classicality enhances energy transfer efficiency.

Abstract

Advancing the debate on quantum effects in light-initiated reactions in biology requires clear identification of non-classical features that these processes can exhibit and utilise. Here we show that in prototype dimers present in a variety of photosynthetic antennae, efficient vibration-assisted energy transfer in the subpicosecond timescale and at room temperature can manifest and benefit from non-classical fluctuations of collective pigment motions. Non-classicality of initially thermalised vibrations is induced via coherent exciton-vibration interactions and is unambiguously indicated by negativities in the phase-space quasi-probability distribution of the effective collective mode coupled to the electronic dynamics. These quantum effects can be prompted upon incoherent input of excitation. Our results therefore suggest that investigation of the non-classical properties of vibrational motions assisting excitation and charge transport, photoreception and chemical sensing processes could be a touchstone for revealing a role for non-trivial quantum phenomena in biology.