# Theory of universal incoherent metallic transport

**Authors:** Sean A. Hartnoll  
**arXiv:** [1405.3651](https://arxiv.org/abs/1405.3651)  
**Date:** 2014-05-14  
**Summary page:** https://www.summarizepaper.com/en/arxiv-id/1405.3651v1/

## Key points

- Theory of universal incoherent metallic transport proposed by Sean A. Hartnoll
- Transport governed by collective diffusion of energy and charge, not quasiparticle or momentum relaxation
- Universal bound on diffusion constants with suggested lower limit of $D \gtrsim \hbar v_F^2/(k_B T)$
- Inspiration from holographic duality, uncertainty principle, and observations of diffusion in strongly interacting non-metallic systems
- Metals approaching theoretical bound exhibit linear increase in resistivity with temperature
- Explanation for phenomena in strongly correlated metals and importance of studying diffusive processes and measuring charge susceptibilities
- Crucial role in understanding high-temperature regimes with $T$-linear resistivity in metals

## Summary

The theory of universal incoherent metallic transport, proposed by Sean A. Hartnoll, suggests that in metals lacking coherence, transport is governed by the collective diffusion of energy and charge rather than quasiparticle or momentum relaxation. This study explores the concept of a universal bound on diffusion constants in such metals, with a suggested lower limit of $D \gtrsim \hbar v_F^2/(k_B T)$. The inspiration for this bound comes from insights from holographic duality and the uncertainty principle, as well as observations of diffusion in strongly interacting non-metallic systems. Metals that approach this theoretical bound exhibit a linear increase in resistivity with temperature, consistent with experimental data across various metals. The idea of universal incoherent transport not only explains phenomena observed in strongly correlated metals but also emphasizes the importance of studying diffusive processes and measuring charge susceptibilities. This proposed bound may play a crucial role in understanding why high-temperature regimes with $T$-linear resistivity are commonly observed in metals. By considering the collective diffusion of energy and charge as fundamental to transport mechanisms in incoherent metals, this theory provides valuable insights into the behavior of diverse metallic systems and motivates further research into their underlying physics.