Quantum correlations of two-mode Gaussian systems in a thermal environment

TL;DR

This paper investigates how quantum entanglement and discord in two-mode Gaussian systems evolve over time when exposed to a thermal environment, revealing entanglement suppression and asymptotic decay of quantum correlations.

Contribution

It provides a detailed analysis of the dynamics of quantum correlations in Gaussian systems within a thermal bath using open system theory, highlighting entanglement suppression and discord decay.

Findings

Entanglement is suppressed at all temperatures, including zero.

Quantum discord decays asymptotically over time.

Total correlations decrease due to thermal environment effects.

Abstract

In the framework of the theory of open systems based on completely positive quantum dynamical semigroups, we give a description of continuous variable quantum entanglement and quantum discord for a system consisting of two non-interacting non-resonant bosonic modes embedded in a thermal environment. We study the time evolution of logarithmic negativity, which characterizes the degree of entanglement, and show that in the case of an entangled initial squeezed thermal state, entanglement suppression takes place for all temperatures of the environment, including zero temperature. We analyze the time evolution of the Gaussian quantum discord, which is a measure of all quantum correlations in the bipartite state, including entanglement, and show that discord decays asymptotically in time under the effect of the thermal bath. We describe also the time evolution of classical correlations and quantum mutual information, which measures the total correlations of the quantum system.