论文标题
XXZ链中局部费米克激发后的纠缠蔓延
Entanglement spreading after local fermionic excitations in the XXZ chain
论文作者
论文摘要
我们研究了在XXZ链的基态以上产生的局部费米式激发的时间演变所产生的纠缠的扩散。通过密度 - 矩阵重新归一化组计算研究所得的熵曲线，并与准粒子Ansatz进行比较。特别是，我们假设纠缠主要是通过以不同速度传播的旋子激发来携带的，并且熵轮廓由涉及到达子系统的蜘蛛的密度分数的概率表达来复制。 ANSATZ在无间隙阶段效果很好，可用于中等的XXZ各向异性值，最终随着其他类型的准粒子激发增长的光谱重量而恶化。此外，如果初始状态受到局部主要武器的激发，我们会观察到熵剖面的非平凡重新缩放。在保形场理论框架中进一步研究了这种效果，并对Luttinger液体理论进行了计算。最后，我们还考虑了在链间隙阶段产生抗铁磁域壁的激发，并再次找到具有乘法因子的改良的准粒子ansatz。
We study the spreading of entanglement produced by the time evolution of a local fermionic excitation created above the ground state of the XXZ chain. The resulting entropy profiles are investigated via density-matrix renormalization group calculations, and compared to a quasiparticle ansatz. In particular, we assume that the entanglement is dominantly carried by spinon excitations traveling at different velocities, and the entropy profile is reproduced by a probabilistic expression involving the density fraction of the spinons reaching the subsystem. The ansatz works well in the gapless phase for moderate values of the XXZ anisotropy, eventually deteriorating as other types of quasiparticle excitations gain spectral weight. Furthermore, if the initial state is excited by a local Majorana fermion, we observe a nontrivial rescaling of the entropy profiles. This effect is further investigated in a conformal field theory framework, carrying out calculations for the Luttinger liquid theory. Finally, we also consider excitations creating an antiferromagnetic domain wall in the gapped phase of the chain, and find again a modified quasiparticle ansatz with a multiplicative factor.
