Tripartite entanglement dynamics following a quantum quench

TL;DR

This paper studies the evolution of tripartite entanglement in quantum spin chains after a quench, revealing an entanglement barrier and the role of tripartite-entangled quasiparticles.

Contribution

It introduces the use of the Markov gap to detect and analyze tripartite entanglement dynamics beyond pair structures in quantum quenches.

Findings

Markov gap is positive at intermediate times indicating tripartite entanglement.

Tripartite entanglement exhibits an entanglement barrier with a delayed peak.

Triplet quasiparticles are responsible for spreading tripartite entanglement.

Abstract

We investigate the dynamics of multipartite entanglement after quenches from initial states which generate multiplets of quasiparticle excitations beyond the usual pair structure. We focus on the dynamics of tripartite entanglement through the lens of the Markov gap -- a computable quantity that signals irreducible tripartite entanglement when positive. In the XX spin chain, we show that the Markov gap is positive at intermediate times, implying the presence of tripartite entanglement. After a time delay, the Markov gap increases and then decays at longer times, thus exhibiting an entanglement barrier. We argue that those qualitative features are consistent with an interpretation of the spreading of tripartite entanglement by triplets of tripartite-entangled quasiparticles.