Universal signature of quantum entanglement across cosmological distances

TL;DR

This paper explores how quantum entanglement across cosmological distances influences inflationary predictions, revealing a universal lower bound on observable effects due to entanglement in the early universe.

Contribution

It introduces a novel application of quantum information theory to inflation, demonstrating how entanglement affects large-scale structure predictions.

Findings

Derived a universal lower bound on entanglement effects

Showed entanglement influences observable cosmological modes

Connected quantum decoherence to inflationary dynamics

Abstract

Although the paradigm of inflation has been extensively studied to demonstrate how macroscopic inhomogeneities in our universe originate from quantum fluctuations, most of the established literature ignores the crucial role that entanglement between the modes of the fluctuating field plays in its observable predictions. In this paper, we import techniques from quantum information theory to reveal hitherto undiscovered predictions for inflation which, in turn, signals how quantum entanglement across cosmological scales can affect large scale structure. Our key insight is that observable long-wavelength modes must be part of an open quantum system, so that the quantum fluctuations can decohere in the presence of an environment of short-wavelength modes. By assuming the simplest model of single-field inflation, and considering the leading order interaction term from the gravitational action, we derive a universal lower bound on the observable effect of such inescapable entanglement.