中文摘要：

Taking into account the intrinsic decoherence,we have investigated quantum correlations in a two-qubit Heisenberg XX model when a nonuniform magnetic field is included.We compare entanglement measured by entanglement of formation,quantum discord and measurement-induced measurement(MID)and illustrate their diferent characteristics.Quantum discord and MID show the same features and always exist even though there is no entanglement in the long time limit.In the time evolution,quantum discord could be generated or enhanced to the stable value,while MID just decreases to the stable value.

英文摘要：

Taking into account the intrinsic decoherence, we have investigated quantum correlations in a two-qubit Heisenberg XX model when a nonuniform magnetic field is included. We compare entanglement measured by entan- glement of formation, quantum discord and measurement-induced measurement （MID） and illustrate their different characteristics. Quantum discord and MID show the same features and always exist even though there is no entangle- ment in the long time limit. In the time evolution, quantum discord could be generated or enhanced to the stable value, while MID just decreases to the stable value.