Quantum optical effects in neuronal microtubules: superradiance under structural disorder

As quantum biology continues to evolve, growing evidence suggests that quantum optical phenomena such as superradiance and subradiance may play functional roles in biological structures. Recent work has applied nonHermitian Hamiltonian models to explore cooperative quantum effects in systems such as microtubule arrays. Celardo et al. developed a formalism incorporating coherent dipole-dipole coupling and radiative losses, revealing the emergence of superradiant states under idealized geometries. Building on this framework, Babcock et al. combined theoretical modeling with experimental fluorescence quantum yield measurements. Although the absolute values differ, their results show that the increase in quantum yield from individual tubulin units to entire microtubules follows a similar trend in both theory and experiment, suggesting the possible presence of superradiant quantum effects. Where previous studies introduced static disorder by adjusting site energies, we advance this approach by modeling tubulin assemblies constructed from alternative Protein Data Bank (PDB) structures and controlled perturbations of chromophore positions and dipole orientations, rather than repeating a single idealized PDB unit. This enables us to investigate how biologically relevant fluctuations in chromophore positions and dipole orientations reshape the light–matter interaction landscape. In particular, we quantify how this structural variability modifies the dipole–dipole coupling matrix and influences the distribution and radiative properties of excitonic eigenstates. Our numerical results show that realistic spatial heterogeneity can shift the conditions under which superradiant states arise, and we discuss the limitations of our current modeling approach and their implications for cooperative UV emission from tryptophan networks in microtubules. This study contributes to the growing effort to understand the role of quantum coherence in neuronal architectures and the physical mechanisms underlying light–matter interactions within the cytoskeleton.