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arXiv · 2509.20647

Quantum metric induced nonlinear thermal noise in PT-symmetric antiferromagnets

Dibyanandan Bhowmick·Amit Agarwal
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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 quantum metric. This effect arises from field-induced modifications to Bloch wavefunctions and band energies, and it dominates in PT-symmetric antiferromagnets where Berry curvature based contributions are forbidden by symmetry. Applying our theory to CuMnAs, we demonstrate that thermal noise provides a direct signature of quantum metric in PT-symmetric antiferromagnets.

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Dibyanandan Bhowmick, Amit Agarwal. 2025-09-25. Quantum metric induced nonlinear thermal noise in PT-symmetric antiferromagnets. https://arxiv.org/abs/2509.20647

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