论文标题
哈伯德链中的磁激发,非经典性和量子唤醒动力学
Magnetic excitations, non-classicality and quantum wake spin dynamics in the Hubbard chain
论文作者
论文摘要
最近的工作表明,量子Fisher信息(QFI)(QFI)是多部分纠缠的见证和磁性van Hove相关性$ g(r,t)$,可以通过精确测量动态旋转结构因子$ s(k,k,组成)的精确测量,可以通过精确测量旋转系统上的无弹性中子散射在旋转系统上的无弹性中子散射中。在这里,我们从理论上将这些想法应用于最接近邻居的半充满哈伯德链,远离强耦合极限。该模型在$ s(k,ω)$中的光谱重量从非相互作用限制($ u = 0 $)中的频谱重新分布,到强耦合($ u \ rightarrow \ infty $),在此减少到heisenberg量子量子链。我们使用密度矩阵重归其化组(DMRG)来找到$ s(k,ω)$,然后从中计算QFI。我们发现QFI随$ u $而生长。通过逼真的能量解决,它可以目睹$ u = 2.5 $(以跳跃的单位)的两部分纠缠,在那里它也会改变斜坡。这一点还距离带宽$ w(u)$和半链von Neumann纠缠熵的变化也很接近。我们通过傅立叶转换$ s(k,ω)$计算$ g(r,t)$。结果表明,以铁电磁灯杆波前的为特征的低$ u $的短期短途动态的交叉,以大型$ u $的类似抗铁磁灯的抗filomagnetic Lightcones和空间周期性的抗铁抗抗铁磁性的抗抗铁磁性。我们发现这个跨界车已在很大程度上完成了$ u = 3 $。因此,我们的结果提供了证据,表明在几个方面,哈伯德链的强耦合极限已经以相对适度的相互作用强度定性地达到。我们讨论了观察$ g(r,t)$ dynamics的实验候选者。
Recent work has demonstrated that quantum Fisher information (QFI), a witness of multipartite entanglement, and magnetic Van Hove correlations $G(r,t)$, a probe of local real-space real-time spin dynamics, can be successfully extracted from inelastic neutron scattering on spin systems through accurate measurements of the dynamical spin structure factor $S(k,ω)$. Here we apply theoretically these ideas to the half-filled Hubbard chain with nearest-neighbor hopping, away from the strong-coupling limit. This model has nontrivial redistribution of spectral weight in $S(k,ω)$ going from the non-interacting limit ($U=0$) to strong coupling ($U\rightarrow \infty$), where it reduces to the Heisenberg quantum spin chain. We use the density matrix renormalization group (DMRG) to find $S(k,ω)$, from which QFI is then calculated. We find that QFI grows with $U$. With realistic energy resolution it becomes capable of witnessing bipartite entanglement above $U=2.5$ (in units of the hopping), where it also changes slope. This point is also proximate to slope changes of the bandwidth $W(U)$ and the half-chain von Neumann entanglement entropy. We compute $G(r,t)$ by Fourier-transforming $S(k,ω)$. The results indicate a crossover in the short-time short-distance dynamics at low $U$ characterized by ferromagnetic lightcone wavefronts, to a Heisenberg-like behavior at large $U$ featuring antiferromagnetic lightcones and spatially period-doubled antiferromagnetism. We find this crossover has largely been completed by $U=3$. Our results thus provide evidence that, in several aspects, the strong-coupling limit of the Hubbard chain is reached qualitatively already at a relatively modest interaction strength. We discuss experimental candidates for observing the $G(r,t)$ dynamics found at low $U$.