2025/09/22 by Subham Dutta Chowdhury, Chowdhury, Subham Dutta, Sean A. Hartnoll +5 · 2 citations
Materials Science · Physics and Astronomy · #FOS: Physical sciences #High Energy Physics - Theory (hep-th) #Quantum many-body systems #Strongly Correlated Electrons (cond-mat.str-el) #Theoretical and Computational Physics #Thermal properties of materials
paper · pdf · doi:10.48550/arxiv.2509.18255
openalex publication_date 2025/09/22 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The Drude-Kadanoff-Martin model is a simple low energy and long wavelength description of charge transport, parameterised by the current relaxation timescale τ, charge diffusivity D and charge compressibility χ. We obtain sharp constraints on these parameters in terms of the microscopic energy and length scales of any underlying lattice model with local and bounded interactions. Our primary tools are upper bounds on the retarded Green's function for the charge density in such a setting. We first note that the Drude-Kadanoff-Martin model cannot pertain at microscopic energy scales because it is inconsistent with the exponential suppression of spectral weight at the highest frequencies in a lattice model. Secondly, under the assumption that the low energy dynamics is captured by the model, we obtain a lower bound on the collective mean free path ℓ ≡ √(τD). This bound is shown to imply a version of the Mott-Ioffe-Regel bound: systems with ℓ much shorter than the lattice length scale cannot have conventional Drude peaks.