外磁场下两量子比特海森堡XXZ模型中量子关联和热纠缠的研究

Quantum correlations and thermal entanglement in a two-qubit Heisenberg XXZ model with external magnetic fields

通过在两量子位上分别施加独立可控的外磁场(B+b)和(B-b),以及改变耦合参数J_z、磁场强度B、磁场不均匀度b和系统的温度kT,探讨了两量子比特XXZ模型中量子关联的变化行为,并在相同参数下与热纠缠做了比较。结果表明:量子关联存在的参数范围比热纠缠更广;而且在一定的参数范围内,量子关联和热纠缠的变化展示出不同的行为。

The quantum correlation of a two-qubit Heisenberg XXZ model was investigated through applying two independent and controllable magnetic fields （B ＋ b） and （B - b） on the two qubits respectively and changing the coupling parameter Jx, magnetic field B, inhomogeneous magnetic field b and temperature kT.The behavior of quantum correlation and that of thermal entanglement under one and the same parameter is compared. The results show that quantum correlation can exist for a wider parameter range than thermal entanglement. In addition, for a certain region of parameter, quantum correlation and thermal entanglement exhibit completely different behaviors