Sudden change in the entanglement Hamiltonian: Phase diagram of an Ising entanglement Hamiltonian
Phys. Rev. B 111, 245126 – Published 10 June, 2025
DOI: https://doi.org/10.1103/ywk9-n2ds
Abstract
The form of the entanglement Hamiltonian varies with the parameters of the original system. Whether there is a singularity is the key problem for demonstrating/negating the universality of the relation between the entanglement spectrum and edge energy spectrum. We carefully study the phase diagram of a 1D Ising entanglement Hamiltonian as an example to clarify the long-standing controversy of the general relation between the entanglement Hamiltonian and original Hamiltonian. Interestingly, even if the singularities indeed exist, the Li-Haldane-Poilblanc conjecture, i.e., the general relation between the entanglement spectrum and edge energy spectrum, seemingly still holds.
