外磁场下XY模型中两量子位热纠缠的性质及其调控研究

在海森堡XY模型中，为了统一研究均匀磁场和非均匀磁场对系统热纠缠的影响，在两个量子位分别施加独立可控的外磁场(B+b)和(B-b). 发现在均匀磁场和低温条件下的纠缠度有一个稳定的平台区并发生纠缠突变. 控制磁场不均匀度b和选择合适的材料就可以获得最有利的纠缠，并大大提高系统退纠缠的临界温度T_c. 调节磁场的B值，可以在更宽的温度范围内实现此体系的纠缠开关. 关键词： 热纠缠度 密度矩阵 XY模型')" href="#">XY模型

On the properties and controlling of thermal entanglement in a two-qubit Heisenberg XY model with external magnetic fields

We investigate the thermal entanglement of Heisenberg-type coupled two-qubit system in the presence of two controllable magnetic fields (B+b) and (B-b). We find that under the condition of low temperature and uniform magnetic field, the entanglement between the two qubits exhibits platform-like behavior. By controlling the inhomogeneous magnetic field b and selecting suitable material we can optimize the thermal entanglement and enhance the critical temperature T_c of dead entanglement. We also find that the entanglement switch can be realized in a broader region of temperature by modulating the uniform field B.