Entanglement Entropy as a Probe Beyond the Horizon

TL;DR

This paper investigates how the entanglement entropy of a free field in de Sitter space is affected by cosmic expansion, revealing a logarithmic dependence on system size that extends beyond the horizon, with implications for cosmology.

Contribution

It analytically demonstrates the logarithmic growth of entanglement entropy due to expansion, extending previous understanding of quantum correlations in cosmological settings.

Findings

Entanglement entropy increases logarithmically with system size.

Expansion induces a term in entropy dependent on the size beyond the horizon.

Results have implications for understanding quantum information in cosmology.

Abstract

The entanglement entropy of a free field in de Sitter space is enhanced by the squeezing of its modes. We show analytically that the expansion induces a term in the entanglement entropy that depends logarithmically on the size of the overall system, which may extend beyond the horizon. In cosmology the size of the system can be identified with the size of a spatially finite universe, or with the wavelength of the first mode that exited the horizon in the beginning of inflation.