Berry connection polarizability induced nonlinear thermal noise
Phys. Rev. B 113, 235405 – Published 2 June, 2026
DOI: https://doi.org/10.1103/h4xf-zcvy
Abstract
Electrical current fluctuations provide a powerful and unconventional probe of band geometry in quantum materials. In particular, intrinsic noise components that are independent of the relaxation time reveal universal band-geometric properties of Bloch electrons. Here, we identify a distinct intrinsic contribution to current noise at second order in the electric field, which is governed by the Berry connection polarizability (BCP), a band-geometric quantity constructed from energy-weighted interband components of the quantum metric. This effect arises from field-induced modifications to Bloch wave functions and band energies, and it contributes to both the longitudinal and transverse noise components. Applying our theory to CuMnAs, we demonstrate that thermal noise provides a direct signature of BCP in crystalline solids.
