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arXiv · 2003.13708

Superdiffusion from emergent classical solitons in quantum spin chains

Jacopo De Nardis·Sarang Gopalakrishnan·Enej Ilievski·Romain Vasseur
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Abstract

Finite-temperature spin transport in the quantum Heisenberg spin chain is known to be superdiffusive, and has been conjectured to lie in the Kardar-Parisi-Zhang (KPZ) universality class. Using a kinetic theory of transport, we compute the KPZ coupling strength for the Heisenberg chain as a function of temperature, directly from microscopics; the results agree well with density-matrix renormalization group simulations. We establish a rigorous quantum-classical correspondence between the "giant quasiparticles" that govern superdiffusion and solitons in the classical continuous Landau-Lifshitz ferromagnet. We conclude that KPZ universality has the same origin in classical and quantum integrable isotropic magnets: a finite-temperature gas of low-energy classical solitons.

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Jacopo De Nardis, Sarang Gopalakrishnan, Enej Ilievski, Romain Vasseur. 2020-03-30. Superdiffusion from emergent classical solitons in quantum spin chains. https://doi.org/10.1103/physrevlett.125.070601

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