Classicalization of Quantum Fluctuation in Inflationary Universe

TL;DR

This paper explores how quantum fluctuations during inflation become classical, highlighting that the classicalization process influences the resulting power spectrum and challenges the notion of a unique inflationary spectrum.

Contribution

It demonstrates that classical correlation and decoherence occur simultaneously during inflation and that the classicalization process affects the predicted power spectrum.

Findings

Classical correlation and decoherence are achieved together during inflation.

The power spectrum depends on the details of the classicalization process.

Inflationary predictions of a unique spectrum may not be valid when classicalization is considered.

Abstract

We discuss the classicalization of a quantum state induced by an environment in the inflationary stage of the universe. The classicalization is necessary for the homogeneous ground sate to become classical non-homogeneous one accompanied with the statistical fluctuation, which is a plausible candidate for the seeds of structure formation. Using simple models, we show that i) the two classicalization criteria, the classical correlation and quantum decoherence, are simultaneously satisfied by the environment and that ii) the power spectrum of the resultant statistical fluctuation depends upon the detail of the classicalization process. Especially, the result ii) means that, taking account of the classicalization process, the inflationary scenario does not necessarily predict the unique spectrum which is usually believed.