Universal prethermalization dynamics of entanglement entropies after a global quench

Understand

We consider the quantum XY model and study the effects of interacting perturbations on the time evolution of the von Neumann and R\'enyi entropies of spin blocks after global quenches.

• We show that the entropies are sensitive to perturbations that break hidden symmetries behind the integrability of the model.
• At times much larger than the characteristic time of the well-known linear increase of the entropies, we identify a time window characterized by a novel linear growth followed by saturation.
• The typical time of the phenomenon is inversely proportional to the perturbation strength and the behavior is trigger off by the extinction of an infinite number of local conservation laws following a non-abelian algebra.