Universality class of a spinor Bose-Einstein condensate far from equilibrium

TL;DR

This paper classifies the universal coarsening dynamics in a 2D ferromagnetic spinor Bose gas far from equilibrium, linking the universality class to the symmetry of the order parameter and defect dynamics.

Contribution

It provides the first classification of nonequilibrium universal dynamics in a quantum spinor Bose gas based on symmetry considerations.

Findings

Spatiotemporal scaling of spin correlations observed

Distinct scaling exponents for different fluid types

Universality class determined by symmetry and defect behavior

Abstract

Scale invariance and self-similarity in physics provide a unified framework to classify phases of matter and dynamical properties near equilibrium in both classical and quantum systems. This paradigm has been further extended to isolated many-body quantum systems driven far from equilibrium, where physical observables exhibit dynamical scaling with universal scaling exponents. Universal dynamics appear in a wide range of scenarios, including cosmology, quark-gluon matter, ultracold atoms, and quantum spin magnets. However, how universal dynamics depend on the symmetry of the underlying Hamiltonian in nonequilibrium systems remain an outstanding challenge. Here, we report on the classification of universal coarsening dynamics in a quenched two-dimensional ferromagnetic spinor Bose gas. We observe spatiotemporal scaling of spin correlation functions with distinguishable scaling exponents that characterize binary and diffusive fluids. The universality class of the coarsening dynamics is determined by the symmetry of the order parameter and the dynamics of the topological defects, such as domain walls and vortices. Our results provide a categorization of the universality classes of far from equilibrium quantum dynamics based on symmetry properties of the system.