【摘要】 利用一种通用量子纠缠度——负值度(Negativity),研究热平衡时在外加磁场(沿z轴)下两量子比特海森伯格XY模型的热纠缠.当各向异性系数γ足够大时,出现纠缠复苏现象,而且对于一有限温度,可以调节外加磁场来产生纠缠.而对各向同性,当温度比临界温度高时,负值度为零,与外加磁场无关.更多还原

【Abstract】 Using a universal entanglement measure,negativity,we investigate the thermal entanglement of two-qubit Heisenberg XY model in thermal equilibrium at temperature T in the presence of an external magnetic field B.When anisotropy parameter γ is large enough there occurs a revival of the entanglement.By adjusting the magnetic field B,one can produce entanglement for any finite T.For isotropic case there is no entanglement above a critical temperature that is independent of the external B field.更多还原