Robustness of Quantum Discord Between Two Noninteracting Qubits in Spin-Star Baths
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We study the dynamics of quantum entanglement and discord between two noninteracting qubits, which couple with spin-star baths, obeying the XY Hamiltonian. We compare the dynamics of quantum discord with that of quantum entanglement. For the initial X-type state, in the common spin bath, the quantum discord is more robust than quantum entanglement. It is found that quantum discord of the two noninteracting qubits can be amplified, even in the regimes where entanglement suddenly disappears. This also points to a fact that the absence of entanglement does not necessarily indicate the absence of quantum correlations.
KeywordsQuantum correlation Quantum discord Spin bath
This work is supported by the Scientific Research Fund of Hunan Provincial Education Department (Grants Nos. 17B055, QSQC1414) and the Key Laboratory of Low-Dimensional Quantum Structures and Quantum Control of Ministry of Education.