"Universal spin dynamics in infinite-temperature one-dimensional quantum magnets"

Maxime Dupont: Joel E. Moore; Physical Review B, 03/12/20.

Additional Authors: Joel E. Moore

Abstract:

We address the nature of spin dynamics in various integrable and nonintegrable, isotropic and anisotropic quantum spin-S chains, beyond the paradigmatic S =1/2 Heisenberg model. In particular, we investigate the algebraic long-time decay ∝t−1/z of the spin-spin correlation function at infinite temperature, using state-ofthe-art simulations based on tensor network methods. We identify three universal regimes for the spin transport, independent of the exact microscopic model: (i) superdiffusive with z =3/2, as in the Kardar-Parisi-Zhang universality class, when the model is integrable with extra symmetries such as spin isotropy that drive the Drude weight to zero,(ii)ballistic with z =1 when the model is integrable with a finite Drude weight,and (iii) diffusive with z =2 with easy-axis anisotropy or without integrability, at variance with previous observations.