Quantized nonlinear transport and its breakdown in Fermi gases with Berry curvature
Phys. Rev. B 113, 075431 – Published 24 February, 2026
DOI: https://doi.org/10.1103/kfwv-7wh4
Abstract
Quantized transport not only exists in gapped topological states but also in metallic states. Recently, Kane proposed a quantized nonlinear conductance in ballistic metals whose value is determined by the Euler characteristic of the Fermi sea [Kane et al., Phys. Rev. Lett. 128, 076801 (2022)]. In this paper, we consider two-dimensional noninteracting fermionic systems whose Fermi surface has nonvanishing Berry curvature. We find that the Berry curvature at the Fermi surface does not affect the quantized nonlinear transport for translationally invariant systems. When spatial inhomogeneity is introduced, such quantization breaks down due to the combined effect of Berry curvature and the gradient of the local potential. Such a breakdown of quantization can be observed in trapped ultracold atoms with topological bands.
