Distinguishing bounce and inflation via quantum signatures from cosmic microwave background

TL;DR

This paper proposes a quantum measure called Dynamical Fidelity Susceptibility (DFS) to distinguish between inflationary and bouncing cosmological models using CMBR data, addressing their conceptual differences.

Contribution

It introduces DFS as a novel quantum signature to differentiate early-universe scenarios, demonstrated on simple models with identical power spectra.

Findings

DFS behaves differently for inflation and bouncing models.

DFS can potentially be used as an observational tool in future space missions.

The method provides a new quantum perspective on early-universe cosmology.

Abstract

Cosmological inflation is a popular paradigm for understanding Cosmic Microwave Background Radiation (CMBR); however, it faces many conceptual challenges. An alternative mechanism to inflation for generating an almost scale-invariant spectrum of perturbations is a \emph{bouncing cosmology} with an initial matter-dominated contraction phase, during which the modes corresponding to currently observed scales exited the Hubble radius. Bouncing cosmology avoids the initial singularity but has fine-tuning problems. Taking an \emph{agnostic view} of the two early-universe paradigms, we propose a quantum measure -- Dynamical Fidelity Susceptibility (DFS) of CMBR -- that distinguishes the two scenarios. Taking two simple models with the same power-spectrum, we explicitly show that DFS behaves differently for the two scenarios. We discuss the possibility of using DFS as a distinguisher in the upcoming space missions.