Distribution and generation of quantum coherence for Gaussian states in de Sitter space

TL;DR

This paper investigates how quantum coherence in Gaussian states is distributed and generated in de Sitter space, revealing robustness of coherence under curvature effects and potential for detecting space curvature.

Contribution

It demonstrates the redistribution and generation of quantum coherence among modes in de Sitter space, highlighting differences from entanglement and the potential for curvature detection.

Findings

Quantum coherence survives at infinite curvature for initially correlated states.

Coherence is more robust in massive scalar fields than in massless ones.

Gravity induces multi-mode coherence even in causally disconnected regions.

Abstract

We study the distribution and generation of quantum coherence for two-mode and multi-mode Gaussian states in de Sitter space. It is found that the quantum coherence is redistributed among the mode in different open charts under the curvature effect of de Sitter space. In particular, the Gaussian coherence for the initially correlated state is found to survive in the limit of infinite curvature, while quantum entanglement vanishing in this limit. Unlike entanglement and steering, the coherence of a massive scalar field is more robust than a massless field under the influence of curvature of de Sitter space. In addition, it is shown that the curvature generates two-mode Gaussian state and three-mode Gaussian state quantum coherence among the open charts, even though the observers are localized in causally disconnected regions. It is worth noting that the gravity-generated three-mode coherence is extremely sensitive to the curvature effect for the conformal and massless scalar fields, which may be in principle employed to design an effective detector for the space curvature.