📝 SummarXiv

Abstract

Strong excitonic coupling and photon antibunching (AB) have been observed together in Venus yellow fluorescent protein dimers and currently lack a cohesive theoretical explanation. In 2019, Kim et al. demonstrated Davydov splitting in circular dichroism spectra, revealing strong J-like coupling, while antibunched fluorescence emission was confirmed by combined antibunching--fluorescence correlation spectroscopy (AB/FCS fingerprinting). To investigate the implications of this coexistence, Venus dimer population dynamics are modeled within a Lindblad master equation framework, justified by the separation of characteristic coupling, dephasing, and thermal relaxation rates. Simulations predict rapid decoherence, yielding bright/dark state mixtures consistent with antibunched fluorescence emission at room temperature. Thus, excitonic coupling and photon AB are reconciled without invoking long-lived quantum coherence. More broadly, fluorescent proteins emerge as tractable model systems for probing evolutionary pressures on chromoprotein photophysics and quantum dynamics. Cryogenic cooling may extend coherence time into the regime required for ultrafast gate operations, suggesting fluorescent protein dimers as a viable platform for bio-inspired qubits.