论文标题
在多体局部阶段中的共振能量尺度和局部可观察结果
Resonant energy scales and local observables in the many-body localised phase
论文作者
论文摘要
我们在局部可观察情况下为无序量子旋转链的多体局部局部（MBL）阶段的共振制定了一种理论。一个关键结果是表明局部可观察物的矩阵元素与多体级别频谱之间存在通用相关性。这揭示了矩阵元素如何编码与共振相关的能量尺度，从而使我们能够证明这些能量是分布的幂律。利用这些结果，我们通过分析计算局部极化和本征态忠诚度敏感性的分布。这些数量中的第一个表征了MBL系统与非相互作用的距离，而第二个则突出了它们对局部扰动的极端敏感性。我们的理论方法是考虑改变局部场的效果，从而诱导光谱特性的参数动力学。我们使用有限系统中精确的对角化来证实我们的结果。
We formulate a theory for resonances in the many-body localised (MBL) phase of disordered quantum spin chains in terms of local observables. A key result is to show that there are universal correlations between the matrix elements of local observables and the many-body level spectrum. This reveals how the matrix elements encode the energy scales associated with resonance, thereby allowing us to show that these energies are power-law distributed. Using these results we calculate analytically the distributions of local polarisations and of eigenstate fidelity susceptibilities. The first of these quantities characterises the proximity of MBL systems to noninteracting ones, while the second highlights their extreme sensitivity to local perturbations. Our theoretical approach is to consider the effect of varying a local field, which induces a parametric dynamics of spectral properties. We corroborate our results numerically using exact diagonalisation in finite systems.
