Characterizing Entanglement Entropy Produced by Non-Linear Scalar Interactions During Inflation

Understand

The density fluctuations that we observe in the universe today are thought to originate from quantum fluctuations produced during a phase of the early universe called inflation.

• By evolving a wavefunction describing two coupled Fourier modes of a scalar field forward through an inflationary epoch, we demonstrate that non-linear effects can result in a generation of entanglement entropy between modes with different momenta in a scalar field during the inflationary period when just one of the modes is observed.
• Through this mechanism, the field would experience decoherence and appear more like a classical distribution today; however the mechanism is not sufficiently efficient to explain classicality.
• We find that the amount of entanglement entropy generated scales roughly as a power law S \propto \lambda^{1.75}, where \lambda is the coupling coefficient of the non-linear potential term.