Entanglement in holographic dark energy models

TL;DR

This paper investigates the entanglement entropy dynamics during the equilibration of holographic dark energy with the cosmic horizon, revealing significant information transfer and entropy jumps that challenge the applicability of quantum field theory frameworks in cosmology.

Contribution

It introduces a detailed analysis of entanglement entropy evolution in holographic dark energy models and discusses limitations of the underlying quantum field theory approach.

Findings

Large entropy gap between system and black hole states.

Strong jump in entanglement entropy during equilibration.

Restrictions on quantum field theory frameworks in cosmological contexts.

Abstract

We study a process of equilibration of holographic dark energy (HDE) with the cosmic horizon around the dark-energy dominated epoch. This process is characterized by a huge amount of information conveyed across the horizon, filling thereby a large gap in entropy between the system on the brink of experiencing a sudden collapse to a black hole and the black hole itself. At the same time, even in the absence of interaction between dark matter and dark energy, such a process marks a strong jump in the entanglement entropy, measuring the quantum-mechanical correlations between the horizon and its interior. Although the effective quantum field theory (QFT) with a peculiar relationship between the UV and IR cutoffs, a framework underlying all HDE models, may formally account for such a huge shift in the number of distinct quantum states, we show that the scope of such a framework becomes tremendously restricted, devoiding it virtually any application in other cosmological epochs or particle-physics phenomena. The problem of negative entropies for the non-phantom stuff is also discussed.