Abstract
Superdiffusive finite-temperature transport has been recently observed in a variety of integrable systems with non-Abelian global symmetries. Superdiffusion is caused by giant Goldstone-like quasiparticles stabilized by integrability. Here, we argue that these giant quasiparticles remain long-lived and give divergent contributions to the low-frequency conductivity , even in systems that are not perfectly integrable. We find, perturbatively, that for translation-invariant static perturbations that conserve energy and for noisy perturbations. The (presumable) crossover to regular diffusion appears to lie beyond low-order perturbation theory. By contrast, integrability-breaking perturbations that break the non-Abelian symmetry yield conventional diffusion. Numerical evidence supports the distinction between these two classes of perturbations.
- Received 24 February 2021
- Accepted 18 June 2021
DOI:https://doi.org/10.1103/PhysRevLett.127.057201
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