Quasi-local Edge Mode in XXX Spin Chain/Circuit with Interaction Boundary Defect
Abstract
We study the Heisenberg spin-1/2 model on a semi-infinite chain - or, equivalently, a trotterized unitary SU(2) symmetric six-vertex quantum circuit - with a boundary defect where the interaction between the two spins nearest the edge differs from that in the bulk. For sufficiently strong boundary interaction we explicitly construct a conserved operator quasi-localized near the boundary using a matrix-product ansatz. This quasi-local edge mode leads to non-decaying boundary correlation functions, corresponding to a nonzero boundary Drude weight. The correlation length of the edge mode diverges at a finite critical value of the boundary interaction, signaling a transition to ergodic boundary dynamics for subcritical interactions.
Keywords
Cite
@article{arxiv.2603.17835,
title = {Quasi-local Edge Mode in XXX Spin Chain/Circuit with Interaction Boundary Defect},
author = {Tomaž Prosen},
journal= {arXiv preprint arXiv:2603.17835},
year = {2026}
}
Comments
5+5 pages in revtex with 5+1 pdf figures