Worldline deconfinement and emergent long-range interaction in the entanglement Hamiltonian and in the entanglement spectrum
Phys. Rev. B 113, 144425 – Published 17 April, 2026
DOI: https://doi.org/10.1103/69gq-s9j8
Abstract
The entanglement spectrum (ES) is a powerful tool for probing topological phases. While its behavior in gapped systems is well understood, its properties in gapless regimes remain unclear. In this work, we employ a quantum Monte Carlo method to study the ES of a two-dimensional square-octagon lattice Heisenberg model at quantum criticality and in the Néel phase. We find that the ES exhibits an M-shape magnon mode with a distinct sublinear dispersion, deviating from the conventional linear magnon. This behavior, similar to that of a one-dimensional long-range Heisenberg chain, reveals the emergence of relevant long-range interactions in the entanglement Hamiltonian. We demonstrate that the mechanism underlying short- and long-range interactions in the entanglement Hamiltonian can be interpreted as the confinement/deconfinement of worldlines in the path integral formulation. Our results reveal that gapless modes can fundamentally change the entanglement Hamiltonian and its spectrum, thereby offering insight into this general phenomenon.
Physics Subject Headings (PhySH)
Corrections
18 May, 2026
Correction: Values given for panels (d), (e), and (f) in the caption to Fig. 3 have been fixed. An author name in Refs. [50–52] was presented incorrectly and has been rectified.
