Effects of environmental noise on quantum charge diffusion in DNA sequences

Charge fluctuations along stacked nucleobases in the DNA double helix play a key role in processes such as DNA repair and replication. While classical charge transfer mechanisms between adjacent bases due to energetic excitations are well established, quantum effects can also contribute significantly. Specifically, the overlap of π-orbitals in well-stacked nucleobases can enable charge delocalization along the DNA double-strand. However, the cellular environment, including water, surrounding molecules, and thermal noise, is thought to induce rapid decoherence, limiting quantum-enhanced charge transport under physiological conditions. To explore charge mobility in such noisy environments, we model quantum diffusion in DNA-inspired two-dimensional tight-binding lattices, considering intrinsic and environmental fluctuations and revealing, via atomistic parametrization, a complex network of charge transport pathways. Our results show that long-range quantum phenomena depend on the carrier type (electrons or holes), base sequence, and noise/disorder characteristics. Notably, spatially correlated low-frequency fluctuations can sustain coherent charge transfer across several bases, whereas moderate vibrational noise can enhance rather than suppress quantum coherence by facilitating tunneling effects. These findings suggest that even under physiological conditions, the DNA structure can support non-classical charge dynamics, offering insights into its potential role in bioelectronic processes and inspiring future models of quantum transport in biological systems.