论文标题
热力学极限中的多体定位和离域动力学
Many-body localization and delocalization dynamics in the thermodynamic limit
论文作者
论文摘要
经过多体定位（MBL）过渡的无序量子系统无法在自己的动态下达到热平衡。然而，由于有限尺寸的效果，基于数值结果的渐近局部或离域动力学区分渐近局部或离域动力学。数值链接的群集扩展（NLCE）提供了一种直接在热力学极限下处理量子系统的方法，但对于没有转换不变性的模型而言，它具有挑战性。在这里，我们证明了NLCE提供了一种强大的工具来探索MBL，通过模拟无序的旋转动态$ 1/2 $ 1/2 $两腿梯子和费米 - 哈伯德链。将NLCE与纯状态的有效实时演变相结合，我们获得了长期尺度上不平衡的衰减的融合结果，并表明，尤其是对于假定的MBL过渡以下的中级疾病，NLCE胜过对具有开放或周期性边界的有限系统的直接模拟。此外，虽然自旋即使在冰冻电荷的强烈混乱的哈伯德链中也被定位，但我们揭露了额外的倾斜电势会导致旋转失衡和无效的行为在可访问时期的急剧下降。我们的作品阐明了超出良好无序的海森堡链之外的系统中MBL的启示，并强调了NLCE对此目的的有用性。
Disordered quantum systems undergoing a many-body localization (MBL) transition fail to reach thermal equilibrium under their own dynamics. Distinguishing between asymptotically localized or delocalized dynamics based on numerical results is however nontrivial due to finite-size effects. Numerical linked cluster expansions (NLCE) provide a means to tackle quantum systems directly in the thermodynamic limit, but are challenging for models without translational invariance. Here, we demonstrate that NLCE provide a powerful tool to explore MBL by simulating quench dynamics in disordered spin-$1/2$ two-leg ladders and Fermi-Hubbard chains. Combining NLCE with an efficient real-time evolution of pure states, we obtain converged results for the decay of the imbalance on long time scales and show that, especially for intermediate disorder below the putative MBL transition, NLCE outperform direct simulations of finite systems with open or periodic boundaries. Furthermore, while spin is delocalized even in strongly disordered Hubbard chains with frozen charge, we unveil that an additional tilted potential leads to a drastic slowdown of the spin imbalance and nonergodic behavior on accessible times. Our work sheds light on MBL in systems beyond the well-studied disordered Heisenberg chain and emphasizes the usefulness of NLCE for this purpose.
