Domain wall melting across a defect

TL;DR

This paper investigates how a localized impurity affects the melting of a domain wall in a free-fermionic chain, revealing enhanced quantum correlations and a transition from logarithmic to linear entanglement growth.

Contribution

It provides exact predictions for entanglement dynamics in the presence of a defect using hydrodynamic and quasiparticle approaches, highlighting universal features.

Findings

Defect induces linear entanglement growth contrasting clean system behavior.

Steady pair production at the defect creates non-local correlations.

Universal subleading logarithmic corrections are characterized.

Abstract

We study the melting of a domain wall in a free-fermionic chain with a localised impurity. We find that the defect enhances quantum correlations in such a way that even the smallest scatterer leads to a linear growth of the entanglement entropy contrasting the logarithmic behaviour in the clean system. Exploiting the hydrodynamic approach and the quasiparticle picture, we provide exact predictions for the evolution of the entanglement entropy for arbitrary bipartitions. In particular, the steady production of pairs at the defect gives rise to non-local correlations among distant points. We also characterise the subleading logarithmic corrections, highlighting some universal features.