用两比特海森伯XY模型研究热几何失协

Thermal geometric discords in a two-qubit Heisenberg XY model

研究磁场、温度及相互作用参数对两量子比特海森伯XY模型的热量子关联影响,其中量子关联用两种改进的几何失协,以及共生度来描述.结果表明:在低温和弱磁场区域,这三个量呈现类似的行为;但是,两种几何失协在对抗温度和磁场上比共生度更强大;在合适的条件下,一种改进的几何失协随磁场的增加而增加,而另一种失协是减小的;特别是,这种改进的几何失协出现突然变化,而另一种失协和共生度没有这种变化.这些结果有助于深入理解不同的几何失协量度以及两类量子关联.

We study the influences of the external magnetic field,temperature,and coupling parameter on the thermal quantum correlation in a two-qubit Heisenberg XY model,where the correlation is described in terms of two modified geometric discords and concurrence.It is shown that those three quantities behave similarly in the regions of lower temperature and weak magnetic field.However,the two geometric discords are more robust against temperature and magnetic field than the concurrence.Moreover,two geometric discords exhibit different behaviors under suitable conditions,that is,one discord increases as the magnetic field rises whereas the other discord decreases.In particular,the discord reveals the phenomenon of sudden change,while neither of other discord and concurrence displays such a phenomenon.