匀强及非匀强磁场中Heisenberg XXX链的纠缠研究(英文)

Entanglement of the Heisenberg XXX spin chain under uniform and nonuniform magnetic fields

研究了匀强及非匀强磁场中反铁磁体Heisenberg XXX链的近邻和次近邻纠缠.结果表明对基态情形,纠缠随磁场B变化呈现阶梯型结构,这可用来构建量子纠缠“放大器”或量子纠缠“开关”.对有限温度情形,引进一非匀强磁场Bi=(-1)iB可以使近邻格点间纠缠在某些区域明显增大,而次近邻格点间纠缠则完全消失;同时引进非匀强磁场Bi=(-1)iB还可以使近邻格点纠缠的临界温度Tcn增大,且Tcn随B的增大而升高,这意味着我们可以通过调节B的大小而在任意温度下得到纠缠.

We study the nearest and next nearest neighbor entanglement of the Heisenberg XXX spin chain （antiferromagnet） under uniform and nonuniform magnetic fields up to 10 spins. At zero absolute temperature, we show that there are staircase structures in concurrence C, this may be used to construct a quantum entanglement ＂amplifier＂ or ＂switch＂. For finite temperature, we show that when a nonuniform magnetic field Bi = （ - 1）^iB is introduced, the nearest neighbor entanglement may be enhanced at certain regions of B and T, while the next nearest neighbor entanglement completely disappeared. The critical temperature T~ at which the nearest neighbor entanglement vanishes is also improved by introducing the nonuniform magnetic field Bi= （ - 1）^iB, Tcn increases with the increase of B, which means one can get entanglement at any temperature by adjusting the magnetic field strength. He