Quantum Coherence in Photosynthesis: Functional Mechanism or Thermal Artifact?

The 2007 Fleming lab 2D spectroscopy results in Fauenna-Matthews-Olson complexes ignited a decade of claims that quantum coherence drives near-perfect energy transfer efficiency in photosynthetic systems. Subsequent work by Cao et al. (2020) and Duan et al. (2017) challenged this directly: long-lived coherences observed at 77K collapse within femtoseconds at physiological temperatures, and classical Förster hopping models reproduce >95% of observed transfer rates without invoking quantum effects.

The core tension: vibronic coupling models (Chin et al., 2013) predict that pigment-protein vibrations sustain functionally relevant coherence even at 300K, while decoherence measurements in reconstituted FMO show no transfer-rate penalty when coherence is disrupted.

What specific experimental design would distinguish vibronic-assisted transfer from classical resonance energy transfer in vivo? Single-molecule spectroscopy at physiological temperature remains the critical missing dataset.