Classical versus quantum evolution for a universe with a positive cosmological constant

TL;DR

This paper compares classical and quantum evolutions in a cosmological model with a positive cosmological constant, analyzing their moments and initial states to identify similarities and differences.

Contribution

It introduces a method to compare classical and quantum probability distributions in cosmology using moment decomposition and analyzes the robustness of results with different initial states.

Findings

Classical and quantum moments are similar for some variables.

Certain variables exhibit significant differences between classical and quantum evolution.

The initial state choice affects the evolution of moments.

Abstract

A homogeneous and isotropic cosmological model with a positive cosmological constant is considered. The matter sector is given by a massless scalar field, which can be used as an internal time to deparametrize the theory. The idea is to study and compare the evolutions of a quantum and a classical probability distribution by performing a decomposition of both distributions in their corresponding moments. For the numerical analysis an initial peaked Gaussian state in the volume will be chosen. Furthermore, in order to check the robustness of certain results, as initial state both a slightly deformed Gaussian, as well as another completely different state, will also be studied. Differences and similarities between classical and quantum moments are pointed out. In particular, for a subset of moments classical and quantum evolutions are quite similar, but certain variables show remarkable differences.