Quantum correlation dynamics in photosynthetic processes assisted by molecular vibrations

TL;DR

This paper models quantum correlation dynamics in photosynthetic systems, showing how vibrational modes influence quantum coherence and correlations, with implications for understanding natural quantum effects and designing quantum technologies.

Contribution

It introduces a simple model of a dimer coupled to vibrational modes, revealing oscillations of quantum correlations and proposing an approximation for environmental effects.

Findings

Quantum correlations oscillate due to vibrational coupling

Off-resonant modes can be approximated as classical noise

Vibrational modes sustain long-lived quantum coherence

Abstract

During the long course of evolution, nature has learnt how to exploit quantum effects. In fact, recent experiments reveal the existence of quantum processes whose coherence extends over unexpectedly long time and space ranges. In particular, photosynthetic processes in light-harvesting complexes display a typical oscillatory dynamics ascribed to quantum coherence. Here, we consider the simple model where a dimer made of two chromophores is strongly coupled with a quasi-resonant vibrational mode. We observe the occurrence of wide oscillations of genuine quantum correlations, between electronic excitations and the environment, represented by vibrational bosonic modes. Such a quantum dynamics has been unveiled through the calculation of the negativity of entanglement and the discord, indicators widely used in quantum information for quantifying the resources needed to realize quantum technologies. We also discuss the possibility of approximating additional weakly-coupled off-resonant vibrational modes, simulating the disturbances induced by the rest of the environment, by a single vibrational mode. Within this approximation, one can show that the off-resonant bath behaves like a classical source of noise.