Hot Cosmic Qubits: Late-Time de Sitter Evolution and Critical Slowing Down

TL;DR

This paper investigates the late-time behavior of a qubit in de Sitter space, revealing critical slowing down near zero effective mass and highlighting the importance of non-Markovian effects and scalar field self-interactions.

Contribution

It introduces a comprehensive analysis of qubit dynamics in de Sitter space, including non-Markovian effects and scalar self-interactions, extending previous Markovian approximations.

Findings

Critical slowing down occurs near zero effective mass.

Non-Markovian effects are significant for accurate late-time dynamics.

Scalar self-interactions cause secular growth, invalidating perturbative predictions.

Abstract

Temporal evolution of a comoving qubit coupled to a scalar field in de Sitter space is studied with an emphasis on reliable extraction of late-time behaviour. The phenomenon of critical slowing down is observed if the effective mass is chosen to be sufficiently close to zero, which narrows the window of parameter space in which the Markovian approximation is valid. The dynamics of the system in this case are solved in a more general setting by accounting for non-Markovian effects in the evolution of the qubit state. Self-interactions for the scalar field are also incorporated, and reveal a breakdown of late-time perturbative predictions due to the presence of secular growth.