Relation between Lyapunov exponents and decoherence for real scalar fields in de Sitter spacetime

We investigate the relationship between orbital instability and decoherence in de Sitter (dS) spacetime. We consider a simple quadratic toy model proposed by Brandenberger Laflamme and Mijic of two interacting scalar fields in a dS background. It admits a modewise separation, with each mode consisti...

Full description

Saved in:
Bibliographic Details
Published in:Physical review. D, Particles, fields, gravitation, and cosmology Particles, fields, gravitation, and cosmology, 2014-12, Vol.90 (12), Article 125039
Main Authors: de Souza, G., Fonseca-Romero, K. M., Sampaio, Marcos, Nemes, M. C.
Format: Article
Language:English
Subjects:
Asymptotic properties
Compressing
Entropy
Instability
Lyapunov exponents
Orbitals
Oscillators
Scalars
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:We investigate the relationship between orbital instability and decoherence in de Sitter (dS) spacetime. We consider a simple quadratic toy model proposed by Brandenberger Laflamme and Mijic of two interacting scalar fields in a dS background. It admits a modewise separation, with each mode consisting of a pair of nonautonomous coupled harmonic oscillators. We show that the (classical) maximal Lyapunov exponent of every mode equals the asymptotic rate of (quantum) von Neumann entropy production of each oscillator, assuming an initial vacuum. We find that for moderately long times after horizon crossing, orbital instability, entropy and single-mode squeezing are larger for increasing coupling strength. If the entropy of an oscillator increases more rapidly than squeezing, for example in the strong-coupling regime for not too high frequencies, the noise of every quadrature of the asymptotic state will be larger than the vacuum noise. The results suggest the possibility that simple, nonlinear interacting physical processes with unstable or chaotic classical counterparts may provide an important contribution to the effectiveness of the classicalization of cosmological scalar fields during a dS stage of spacetime expansion.
ISSN:1550-7998
1550-2368
DOI:10.1103/PhysRevD.90.125039