有限温度下受控自旋链的纠缠动力学研究

Dynamics of Entanglement in Driven Spin Chains at Finite Temperatures

自旋耦合常数随时间变化的量子XY链中,首末自旋间的远程纠缠将随驱动频率变化而改变,当驱动频率等于2B时,纠缠达到最大值,即产生纠缠共振[1].本文主要研究温度、各向异性参量对纠缠共振的影响及有限温度下链长对纠缠共振的影响.研究发现,零温下,各向异性参量取1时,纠缠共振峰值达到最大;各向异性参量取0时,纠缠共振峰值降为0.随着温度升高,纠缠共振点位置不变,但是纠缠的大小随温度的升高逐渐减小.随着自旋链的增长,纠缠共振峰值降低.

For quantum XY spin chains with time-dependent spin-spin coupling, it is well known that the evolution of concurrence will vary with the change of the driving frequency, and the concurrence reaches its maximum when the driving frequency equals 2B. In this paper, we investigate the effects of temperature and anisotropy parameter on the entanglement resonance, and the evolution of concurrence for different length of the chain at finite temperatures is also studied. We find that, at T=0K, the peak of entanglement resonance reaches its maximum at γ=1, the value of entanglement decreases to zero at γ=0. The position of entanglement resonance does not change as the temperature increases, but the value of entanglement decreases with the increase of temperature. The peak of entanglement resonance decreases with the increase of the chain＇s length.