Analytical results for the entanglement Hamiltonian of a free-fermion chain

Abstract

We study the ground-state entanglement Hamiltonian for an interval of N sites in a free-fermion chain with arbitrary filling. By relating it to a commuting operator, we find explicit expressions for its matrix elements in the large-N limit. The results agree with numerical calculations and show that deviations from the conformal prediction persist even for large systems.