Large scale quantum entanglement in de Sitter spacetime

We investigate quantum entanglement between two symmetric spatialregions in de Sitter space with the Bunch-Davies vacuum. As a discretized model of the scalar field for numerical simulation, we consider a harmonic chain model. Using the coarse-grained variables for the scalar field, it is shown that the multipartite entanglement on the superhorizon scale exists by checking the monogamy relation for the negativity which quantifies the entanglement between the two regions. Further, we consider the continuous limit of this model without coarse-graining and find that non-zero values of the logarithmic negativity exist even if the distance between two spatial regions is larger than the Hubble horizon scale.