Coherent Energy Transfer under Incoherent Light Conditions

Area of Science:

• Photosynthetic light-harvesting complexes
• Quantum dynamics in biological systems
• Ultrafast spectroscopy

Background:

• Two-dimensional electronic spectroscopy (2DES) reveals coherent dynamics in light-harvesting antennae using coherent laser pulses.
• A debate exists on whether this coherence persists under natural, incoherent sunlight illumination.
• Photosynthetic systems often exhibit nonequilibrium phonon dynamics.

Purpose of the Study:

• To investigate the possibility of quantum coherent energy transfer in light-harvesting antennae under incoherent light excitation.
• To explore the role of phonon environment dynamics in maintaining electronic coherence.
• To reconcile observations from 2DES with natural illumination conditions.

Main Methods:

• Theoretical modeling of energy transfer processes.
• Analysis of non-Markovian dynamics of electronic excitations.
• Consideration of nonequilibrium phonon bath effects.

Main Results:

• Quantum coherent energy transfer can occur even when excitation originates from incoherent light.
• Nonequilibrium dynamics of the phonon environment can induce and sustain quantum coherence.
• Observed coherent dynamics are linked to non-Markovian evolution of electronic states.

Conclusions:

• Light-harvesting antennae may possess inherent mechanisms to support quantum coherent evolution under natural, incoherent sunlight.
• Phonon-environment interactions play a crucial role in mediating coherence in biological light harvesting.
• The findings challenge the notion that coherence is solely an artifact of coherent laser excitation.