  Utilizing the holographic technique, we investigate how the entanglement
entropy evolves along the RG flow. After introducing a new generalized
temperature which satisfies the thermodynamics-like law even in the IR regime,
we find that the renormalized entropy and the generalized temperature in the IR
limit approach the thermal entropy and thermodynamic temperature of a real
thermal system. This result implies that the microscopic quantum entanglement
entropy in the IR region leads to the thermodynamic relation up to small
quantum corrections caused by the quantum entanglement near the entangling
surface. Intriguingly, this IR feature of the entanglement entropy universally
happens regardless of the detail of the dual field theory and the shape of the
entangling surface. We check this IR universality with a most general geometry
called the hyperscaling violation geometry which is dual to a relativistic
non-conformal field theory.
