Time evolution of entanglement entropy in holographic FLRW cosmologies

Abstract

To understand the time-dependent quantum correlation in expanding universes, we study the time-dependent entanglement entropy in the braneworld model. If we take into account a generalized string cloud geometry caused by uniformly distributed open strings, cosmologies on the braneworld result in the standard Friedmann-Lemakre-Robertson-Walker cosmologies with various matter contents. On the dual field theory side, open strings are reinterpreted as fundamental matter, while the black hole mass corresponds to the excitation energy of massless gauge bosons. We show how the string cloud geometry is matched to various braneworld cosmologies, for example, eternal inflation and radiation- and matter-dominated universes. Then we investigate how the entanglement entropy evolves in those expanding universes.