Breakdown of Self-Averaging at Quantum Hall Transitions
Phys. Rev. Lett. 137, 056603 – Published 28 July, 2026
DOI: https://doi.org/10.1103/7cnz-jsg1
Abstract
We study the full distribution of the zero-temperature Hall conductivity in a lattice model of the integer quantum Hall effect across disorder realizations. Near the plateau transition, the distributions develop heavy power-law tails with exponent , implying a finite mean but divergent variance. The tail persists across system sizes, correlation lengths of the disorder potential, and fillings indicating that Hall conductivity is not self-averaging at criticality. The exponent is qualitatively compatible with predictions from random-matrix models of Berry curvature fluctuations, hinting at a universal statistical structure of the quantum Hall critical regime.