Decoherence of quantum discord in an asymmetric-anisotropy spin system

TL;DR

This paper studies how quantum discord and entanglement decay over time in an asymmetric-anisotropy Heisenberg spin system, revealing that discord decays asymptotically and can be enhanced by interactions at finite temperatures.

Contribution

It provides analytical and numerical analysis of quantum discord decay in an asymmetric anisotropic spin system, highlighting differences from entanglement dynamics and the role of interactions.

Findings

Quantum discord decays asymptotically under local Markovian reservoirs.

Entanglement exhibits sudden death, unlike discord.

Asymmetric interactions can enhance thermal discord at finite temperatures.

Abstract

The decoherence of quantum correlation is investigated in the Heisenberg spin system with the asymmetric anisotropic interactions. The quantum entanglement and discord are used to quantify the quantumness of the correlations. By the analytical and numerical methods, we find that quantum discord decays asymptotically in time under the effects of the independent local Markovian reservoirs. This is markedly different from the sudden change of the entanglement. Before the disappearance of the entanglement, the dynamic behaviour of quantum discord is very similar to that of the entanglement. It is also shown that the discord declines rapidly for the interacting spin system compared with the case of noninteracting qubits. At an arbitrary finite temperature, the nonzero thermal discord can be enhanced by the asymmetric anisotropic interactions which induce quantum fluctuations.