Enhancing light-harvesting power with coherent vibrational interactions: a quantum heat engine picture

TL;DR

This paper proposes a quantum heat engine model demonstrating how coherent vibrational interactions can enhance light-harvesting efficiency beyond thermal limits, with implications for biological systems.

Contribution

It introduces a quantum design principle where coherent energy exchange boosts light-harvesting power, supported by a prototype heat engine illustrating this quantum advantage.

Findings

Coherent vibrational interactions can increase power output.

Quantum advantage is quantifiable via thermodynamic measures.

Relevance to natural light-harvesting structures is demonstrated.

Abstract

Recent evidence suggests that quantum effects may have functional importance in biological light-harvesting systems. Along with delocalized electronic excitations, it is now suspected that quantum coherent interactions with certain near-resonant vibrations may contribute to light-harvesting performance. However, the actual quantum advantage offered by such coherent vibrational interactions has not yet been established. We investigate a quantum design principle, whereby coherent exchange of single energy quanta between electronic and vibrational degrees of freedom can enhance a light-harvesting system's power above what is possible by thermal mechanisms alone. We present a prototype quantum heat engine which cleanly illustrates this quantum design principle, and quantify its quantum advantage using thermodynamic measures of performance. We also demonstrate the principle's relevance in parameter regimes connected to natural light-harvesting structures.