Thermal Quantum Discord Of XXZ Heisenberg Chains

The Heisenberg spin chain is a conclusive system to be the data bus for a quantum circuit. It can help to accomplish the quantum information transfer availably for its pre-engineering, high fidelity, and the realization of quantum communication over the finite sites. The discord is a more convenient description of quantum entanglement dynamics for the multi-partite system which has been developed within several years. It could work well for the analysis on the pairwise correlation of the multi-partite system.We investigate how quantum discord (QD) of an one-dimensional two-qubit XYZ Heisenberg chain in thermal equilibrium depends on the temperature T of the bath. We also show that the behavior of thermal QD differs in many unexpected ways from thermal entanglement.We compute the quantum discord (QD) and the entanglement (EoF) between nearest qubits (spin-1/2) in an infinite chain described by the Heisenberg model (XXZ Hamiltonian) at finite temperature. The chain is in the thermodynamic limit and thermalized with a reservoir at temperature T. We show that QD, in contrast to EoF and other thermodynamic quantities, spotlights the critical points associated to quantum phase transition (QPT) for this model even at finite T. This remarkable property of QD may have important implications for experimental characterization of QPTs when one is unable to reach temperatures below which a QPT can be seen.