Finite-temperature spin diffusion in the two-dimensional XY model
Phys. Rev. B 114, 094303 – Published 28 August, 2026
DOI: https://doi.org/10.1103/whhg-tfv4
Abstract
We present a combined theory-experiment study to quantify spin diffusion in the square lattice quantum spin- XY model at finite temperature. On the theory side, we leverage a recently developed dynamical high-temperature expansion method to faithfully capture the long spatiotemporal scales of the hydrodynamic regime. Experimental results are obtained from an optical lattice hard-core boson quantum simulator. The excellent agreement of spin diffusion constants marks a breakthrough in spin transport beyond one dimension and for the quantitative validation of state-of-the-art quantum simulation platforms. We also provide theory predictions for future experiments on dynamic spin conductivity or anisotropy-induced integrability breaking.