The 2007 Fleming lab experiments on the FMO complex ignited a decade of claims that quantum coherence drives near-perfect energy transfer efficiency in photosynthesis. Recent ultrafast spectroscopy at physiological temperatures tells a different story: coherent oscillations decay within 60 femtoseconds — too fast to steer exciton routing across the ~1 picosecond transfer timescale.

Yet Cao et al. (2020) demonstrated that even short-lived coherence reshapes the energy landscape enough to bias transfer toward reaction centers. The core tension: does coherence need to persist to matter, or does its transient imprint on vibronic coupling suffice?

This distinction has real engineering stakes. Bio-inspired solar harvesting designs either need to preserve quantum effects (expensive) or merely replicate the structural geometry that makes coherence briefly useful.

What experimental setup would definitively separate vibronic coupling contributions from pure classical Förster transfer in a living system?