Could light harvesting complexes exhibit non-classical effects at room temperature?

TL;DR

This paper investigates whether classical theories can explain quantum-like coherence effects in light-harvesting complexes at room temperature, proposing tests that could distinguish quantum from classical explanations.

Contribution

It introduces Leggett-Garg-type tests for classical theories and demonstrates their potential to reveal quantum coherence in biological systems at ambient conditions.

Findings

Violations of Leggett-Garg inequality possible despite decoherence

Some quantum effects persist at room temperature

Classical theories may not fully explain observed coherence

Abstract

Mounting experimental and theoretical evidence suggests that coherent quantum effects play a role in the efficient transfer of an excitation from a chlorosome antenna to a reaction center in the Fenna-Matthews-Olson protein complex. However, it is conceivable that a satisfying alternate interpretation of the results is possible in terms of a classical theory. To address this possibility, we consider a class of classical theories satisfying the minimal postulates of macrorealism and frame Leggett-Garg-type tests that could rule them out. Our numerical simulations indicate that even in the presence of decoherence, several tests could exhibit the required violations of the Leggett-Garg inequality. Remarkably, some violations persist even at room temperature for our decoherence model.