A class of entangled and diffeomorphism-invariant states in loop quantum gravity: Bell-network states

Abstract Bell-network states constitute a class of diffeomorphism-invariant and entangled states of the geometry within loop quantum gravity (LQG) that satisfy an area-law for the entanglement entropy in the limit of large spins. The fluctuations of the geometry for a Bell-network state are entangled, similar to those in the semiclassical limit as described by quantum field theory in curved spacetimes. We present a comprehensive analysis of the effective geometry of Bell-network states on a dipole graph. This analysis provides a detailed characterization of the quantum geometry of a class of diffeomorphism-invariant, area-law states representing homogeneous and isotropic configurations in loop quantum gravity, which may be explored as boundary states for the dynamics of the theory.