Quantifying nonclassicality and entanglement of Gaussian states

TL;DR

This paper presents methods to calculate the robustness of nonclassicality and entanglement in Gaussian states, providing analytical results for various modes and revealing their physical significance in quantum information processing.

Contribution

It introduces a systematic approach to quantify nonclassicality and entanglement robustness in Gaussian states, including analytical calculations for multiple modes.

Findings

Robustness measures are analytically derived for one-mode, two-mode, and multimode Gaussian states.

Nonclassicality equals entanglement in two-mode squeezed thermal states.

Nonclassicality and entanglement differ significantly in multimode Gaussian states.

Abstract

Quantification of nonclassicality and entanglement in a quantum state is crucial for quantum advantage in information processing and computation. Robustness is one of the tractable measures for quantifying quantum resources. Gaussian states are important in continuous variable quantum information for their theoretically simple and experimentally easily accessible. We provide the method of how to calculate the robustness of nonclassicality and enatnglement for Gaussian states. The robustness of nonclassicality or entanglement is demonstrated analytically for one-mode, two-mode Gaussain states and multimode symmetric Gaussian states, the result shows a clear physical meaning for the origin of nonclassicality and entanglement. For squeezed thermal states, the nonclassicality is equal to the entanglement for the two-mode case, while they are far apart for multimode cases.