Noncommuting zero-noise and zero-frequency limits in particle-hole symmetric fluids

Fuente: arXiv
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Autori principali: McCulloch, Ewan, Vasseur, Romain, Gopalakrishnan, Sarang
Natura: Preprint
Pubblicazione: 2026
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author McCulloch, Ewan
Vasseur, Romain
Gopalakrishnan, Sarang
author_facet McCulloch, Ewan
Vasseur, Romain
Gopalakrishnan, Sarang
contents In charged fluids obeying particle-hole symmetry, such as the Dirac fluid in graphene, charge transport is diffusive despite the presence of ballistically propagating sound waves: sound waves "hydrodynamically decouple" from the slower charge fluctuations. For quasi-one-dimensional fluids, we show that this symmetry-protected charge diffusion is not smoothly connected to the normal diffusion that arises when momentum conservation is broken by noise (or static impurities). Instead, the charge diffusion constant is a discontinuous function of noise, which (in the weak-noise limit) depends only on the ratio of momentum and energy relaxation rates. In the special limit of momentum-conserving noise (e.g., spatially uniform fluctuations of the Hamiltonian), the diffusion constant diverges in the presence of noise. We describe the resulting superdiffusion in terms of coupled Burgers equations. We present a general mechanism--hydrodynamic recoupling--by which weak noise can induce singular changes in transport coefficients. Our results highlight the limits of zero-noise extrapolation for predicting dynamical quantities like diffusion constants.
format Preprint
id arxiv_https___arxiv_org_abs_2601_02475
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Noncommuting zero-noise and zero-frequency limits in particle-hole symmetric fluids
McCulloch, Ewan
Vasseur, Romain
Gopalakrishnan, Sarang
Statistical Mechanics
Mesoscale and Nanoscale Physics
Quantum Gases
Strongly Correlated Electrons
In charged fluids obeying particle-hole symmetry, such as the Dirac fluid in graphene, charge transport is diffusive despite the presence of ballistically propagating sound waves: sound waves "hydrodynamically decouple" from the slower charge fluctuations. For quasi-one-dimensional fluids, we show that this symmetry-protected charge diffusion is not smoothly connected to the normal diffusion that arises when momentum conservation is broken by noise (or static impurities). Instead, the charge diffusion constant is a discontinuous function of noise, which (in the weak-noise limit) depends only on the ratio of momentum and energy relaxation rates. In the special limit of momentum-conserving noise (e.g., spatially uniform fluctuations of the Hamiltonian), the diffusion constant diverges in the presence of noise. We describe the resulting superdiffusion in terms of coupled Burgers equations. We present a general mechanism--hydrodynamic recoupling--by which weak noise can induce singular changes in transport coefficients. Our results highlight the limits of zero-noise extrapolation for predicting dynamical quantities like diffusion constants.
title Noncommuting zero-noise and zero-frequency limits in particle-hole symmetric fluids
topic Statistical Mechanics
Mesoscale and Nanoscale Physics
Quantum Gases
Strongly Correlated Electrons
url https://arxiv.org/abs/2601.02475