Quantum state evolution in an environment of cosmological perturbations

TL;DR

This paper investigates how quantum states of cosmological perturbations evolve through different universe epochs, revealing stochastic behavior and the effects of squeezing on quantum noise.

Contribution

It introduces a detailed analysis of quantum state evolution in cosmological environments, including the derivation of a stochastic equation for particle motion and the impact of squeezing.

Findings

Particle motion described by a stochastic equation with cosmological noise

Squeezing affects the noise properties of perturbations

Density matrix calculations for scalar and tensor perturbations

Abstract

We study the pure and thermal states of quantized scalar and tensor perturbations in various epochs of Universe evolution. We calculate the density matrix of non-relativistic particles in an environment of these perturbations. We show that particle's motion can be described by a stochastic equation with a noise coming from the cosmological environment. We investigate the squeezing of Gaussian wave packets in different epochs and its impact upon the noise of quantized cosmological perturbations.