Hidden quantum effects reshape how scientists predict material conductivity
Researchers have discovered that computer models of how electricity flows through materials miss crucial physics — complex interactions between electrons that only show up in precise measurements. The finding affects how engineers design better semiconductors and could improve predictions for emerging quantum devices and high-temperature superconductors.
Originaltitel: Nonlocal Correlation Effects in dc and Optical Conductivity of the Hubbard Model
Conductivity is one of the most direct probes of electronic systems, yet its theoretical description remains challenging in the presence of strong nonlocal correlations. In this Letter, we analyze the conductivity of the half-filled single-band Hubbard model and identify the role of spatial correlations across the Mott transition. We show that in the correlated metallic regime, an accurate description of the conductivity requires not only the correct spectral function but also the inclusion of complex multielectron processes encoded in vertex corrections. The crossover to the Mott insulating regime is marked by a vanishing contribution of vertex corrections to the dc conductivity. However, in the Mott insulating case vertex corrections remain significant for the optical conductivity.