Dynamical quantum correlations after sudden quenches

TL;DR

This paper studies how bipartite quantum correlations evolve over time after sudden parameter changes in a spin chain, revealing periodic cusps and long-term enhancements linked to quantum criticality.

Contribution

It introduces a mean-field fermionic approach to analyze dynamical quantum discord and concurrence after quenches in the XXZ chain, highlighting new behaviors near critical points.

Findings

Quantum correlations show periodic cusps after quenches to critical points.

Long-term quantum discord can be enhanced by quenches away from criticality.

Next-nearest-neighbor quantum discord persists in the gapped phase after a transverse field quench.

Abstract

We employ the mean-field approach in the fermionic picture of the spin-1/2 XXZ chain to investigate the dynamics of bipartite quantum discord and concurrence under sudden quenching. In the case, when quenching is performed in the anisotropy from an initial value to the critical point, the quantum correlations show periodic cusps in time. Moreover, the first suppression (cusp) in quantum correlations can be explained in terms of the semi-classical picture of quasiparticle propagation. On the other hand, quenching to, as well as away from the criticality point shows that the longtime pairwise quantum discord gets enhanced from its initial state. Finally, we show that in the gapped region a quench in the transverse field displays survival of the next-nearest-neighbor quantum discord. Our results provide a further insight into the dynamical behavior of quantum correlations and their connections to quantum criticality.