Journal of High Energy Physics

, 2019:157 | Cite as

The first heat: production of entanglement entropy in the early universe

  • Sergei KhlebnikovEmail author
  • Akhil Sheoran
Open Access
Regular Article - Theoretical Physics


Entanglement entropy (EE) of a spatial region quantifies correlations between the region and its surroundings. For a free scalar in the adiabatic vacuum in de Sitter space the EE is known to remain low, scaling as the surface area of the region. Here, we study the evolution of entanglement after the universe transitions from de Sitter to flat space. We concentrate on the case of a massless minimally coupled scalar. We find numerically that, after the de Sitter stage ends, the EE and the Ŕenyi entropy rapidly grow and saturate at values obeying the volume law. The final state of the subsystem (region) is a partially thermalized state reminiscent of a generalized Gibbs ensemble. We comment on application of our results to the question of when and how cosmological perturbations decohere.


Cosmology of Theories beyond the SM Integrable Field Theories Classical Theories of Gravity Field Theories in Lower Dimensions 


Open Access

This article is distributed under the terms of the Creative Commons Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in any medium, provided the original author(s) and source are credited


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© The Author(s) 2019

Authors and Affiliations

  1. 1.Department of Physics and AstronomyPurdue UniversityWest LafayetteU.S.A.

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