Quantum discord evolution of three-qubit states under noisy channels

TL;DR

This paper studies how quantum discord evolves in three-qubit states under noisy environments, revealing robustness differences between GHZ and W states and comparing quantum discord's resilience to entanglement.

Contribution

It provides a detailed analysis of quantum discord dynamics in three-qubit states under various dissipative channels, highlighting robustness properties and differences from entanglement.

Findings

Quantum discord in GHZ state is unaffected by σ_x channel.

W state shows greater robustness than GHZ under most channels.

Quantum discord is generally more resilient than entanglement.

Abstract

We investigated the dissipative dynamics of quantum discord for correlated qubits under Markovian environments. The basic idea in the present scheme is that quantum discord is more general, and possibly more robust and fundamental, than entanglement. We provide three initially correlated qubits in pure Greenberger-Horne-Zeilinger (GHZ) or W state and analyse the time evolution of the quantum discord under various dissipative channels such as: Pauli channels $\sigma_{x}$, $\sigma_{y}$, and $\sigma_{z}$, as well as depolarising channels. Surprisingly, we find that under the action of Pauli channel $\sigma_{x}$, the quantum discord of GHZ state is not affected by decoherence. For the remaining dissipative channels, the W state is more robust than the GHZ state against decoherence. Moreover, we compare the dynamics of entanglement with that of the quantum discord under the conditions in which disentanglement occurs and show that quantum discord is more robust than entanglement except for phase flip coupling of the three qubits system to the environment.