Density Fluctuations in the Oscillatory Phase of Nonclassical Inflaton in FRW Universe

TL;DR

This paper investigates quantum fluctuations of a non-classical inflaton in an FRW universe using coherent and squeezed states, deriving solutions for the semiclassical Einstein equations and analyzing the validity of semiclassical theory during the inflaton's oscillatory phase.

Contribution

It introduces a novel application of quantum optics formalisms to model non-classical inflaton states in cosmology and derives perturbative solutions for the semiclassical Einstein equations in this context.

Findings

Power-law expansion solutions in coherent and squeezed states

Semiclassical theory validity depends on small squeezing parameter

Quantum fluctuations analyzed in different non-classical states

Abstract

Using coherent and squeezed state formalisms of quantum optics for a minimally coupled non-classical inflaton in the FRW mertic is studied, in semiclassical theory of gravity. The leading order solution for the semiclassical Einstein equations in the coherent, squeezed and squeezed vacuum states are obtained perturbatively and are exhibit powerlaw expansion behaviour. The validity of the semiclassical theory is examined in the squeezed vacuum state in the oscillatory phase of the inflaton. The semiclassical theory in the oscillatory phase of the non-classical inflaton holds only if the associated squeezing parameter is much less compared to unity. Quantum fluctuations of the inflaton is also examined in coherent and squeezed state formalisms.