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arXiv · 2402.18661

Slow crossover from superdiffusion to diffusion in isotropic spin chains

Catherine McCarthy·Sarang Gopalakrishnan·Romain Vasseur
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Abstract

Finite-temperature spin transport in integrable isotropic spin chains (i.e., spin chains with continuous nonabelian symmetries) is known to be superdiffusive, with anomalous transport properties displaying remarkable robustness to isotropic integrability-breaking perturbations. Using a discrete-time classical model, we numerically study the crossover to conventional diffusion resulting from both noisy and Floquet isotropic perturbations of strength $\lambda$. We identify an anomalously-long crossover time scale $t_\star \sim \lambda^{-\alpha}$ with $\alpha \approx 6$ in both cases. We discuss our results in terms of a kinetic theory of transport that characterizes the lifetimes of large solitons responsible for superdiffusion.

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Catherine McCarthy, Sarang Gopalakrishnan, Romain Vasseur. 2024-02-28. Slow crossover from superdiffusion to diffusion in isotropic spin chains. https://doi.org/10.1103/physrevb.110.l180301

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