Sensitivity to perturbations in the three-dimensional Anderson model (opens in new tab)

We investigate the fidelity susceptibility, which quantifies the sensitivity of single-particle eigenstates to perturbations, in the three-dimensional Anderson model. As a function of disorder strength $W$, it exhibits two distinct peaks. The first peak signals a crossover at weak disorder strength from plane-wave states to single-particle quantum chaos, and its position shifts toward $W\to 0$ in the thermodynamic limit. The second peak emerges,...