2020/10/31 by Matthias Gruber, Viktor Eisler · 13 citations
Mathematics · Physics and Astronomy · #Algebraic structures and combinatorial models #Ansatz #Antiferromagnetism #Conformal field theory #Excited state #Quantum entanglement #Quantum many-body systems #Quasiparticle #Renormalization group #Spinon #Topological Materials and Phenomena #cond-mat.stat-mech #hep-th
paper · pdf · doi:10.21468/scipostphys.10.1.005
published in SciPost Physics 10(1) (SciPost.org) · 29 pages, 10 figures, error in Fig. 1 corrected + minor changes
openalex created_date 2020/10/15 · arxiv created 2020/12/18 · openalex publication_date 2021/01/12 · arxiv updated 2021/01/13 · openalex updated_date 2026/08/06
We study the spreading of entanglement produced by the time evolution of a local fermionic excitation created above the ground state of the XXZ chain. The resulting entropy profiles are investigated via density-matrix renormalization group calculations, and compared to a quasiparticle ansatz. In particular, we assume that the entanglement is dominantly carried by spinon excitations traveling at different velocities, and the entropy profile is reproduced by a probabilistic expression involving the density fraction of the spinons reaching the subsystem. The ansatz works well in the gapless phase for moderate values of the XXZ anisotropy, eventually deteriorating as other types of quasiparticle excitations gain spectral weight. Furthermore, if the initial state is excited by a local Majorana fermion, we observe a nontrivial rescaling of the entropy profiles. This effect is further investigated in a conformal field theory framework, carrying out calculations for the Luttinger liquid theory. Finally, we also consider excitations creating an antiferromagnetic domain wall in the gapped phase of the chain, and find again a modified quasiparticle ansatz with a multiplicative factor.