2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/139297Entanglement in the ground state of the XY model on the infinite chain can be measured by the von Neumann entropy of a block of neighboring spins. We study a double scaling limit: the size of the block is much larger then 1 but much smaller then the length of the whole chain. In this limit, the entropy of the block approaches a constant. The limiting entropy is a function of the anisotropy and of the magnetic field. The entropy reaches minima at product states and increases boundlessly at phase transitions.6 pages, 1 figureQuantum PhysicsStatistical MechanicsHigh Energy Physics - Theorytext