Amplification of quantum discord between two uncoupled qubits in a common environment by phase decoherence

TL;DR

This paper analytically investigates how quantum discord between two uncoupled qubits in a common environment can be amplified or protected over time, revealing conditions for stable amplification and sudden changes in quantum correlations.

Contribution

It demonstrates the possibility of amplifying and protecting quantum discord in two uncoupled qubits within a common environment, highlighting stable amplification and critical time effects.

Findings

Quantum discord can be greatly amplified or protected for certain initial states.

Stable amplification occurs for identical qubits, protection for different qubits with large detuning.

Quantum discord exhibits sudden change at a critical time t_c.

Abstract

We study analytically the dynamic behaviors of quantum correlation measured by quantum discord between two uncoupled qubits, which are immersed in a common Ohmic environment. We show that the quantum discord of the two noninteracting qubits can be greatly amplified or protected for certain initially prepared $X$-type states in the time evolution. Especially, it is found that there does exist the stable amplification of the quantum discord for the case of two identical qubits, and the quantum discord can be protected for the case of two different qubits with a large detuning. It is also indicated that in general there does exist a sudden change of the quantum discord in the time evolution at a critic time point $t_c$, and the discord amplification and protection may occur only in the time interval $0<t\leq t_c$ for certain $X$-type states. This sheds new light on the creation and protection of quantum correlation.