2023/08/05 by Del Vecchio, Simone, Fröhlich, Jürg, Pizzo, Alessandro +1
#FOS: Physical sciences #Mathematical Physics (math-ph)
paper · doi:10.48550/arxiv.2308.02811
In this paper we study the low-lying spectrum of the AKLT model perturbed by small, finite-range potentials and with open boundary conditions imposed at the edges of the chain. Our analysis is based on the local, iterative Lie Schwinger block-diagonalization method which allows us to control small interaction terms localized near the boundary of the chain that are responsible for the possible splitting of the ground-state energy of the AKLT Hamiltonian into energy levels separated by small gaps. This improves earlier results concerning the persistence of the so called bulk gap in these models, besides illustrating the power of our general methods in a non-trivial application.