Statistics of Wigner delay time in Anderson disordered systems

We numerically investigate the statistical properties of Wigner delay time in Anderson disordered 1D, 2D, and quantum dot (QD) systems. The distribution of proper delay time for each conducting channel is found to be universal in 2D and QD systems for all Dyson's symmetry classes and shows a piecewise-power-law behavior in the strongly localized regime. Two power-law behaviors were identified with asymptotical scaling τ^-1.5 and τ^-2, respectively, that are independent of the number of conducting channels and Dyson's symmetry class. Two power-law regimes are separated by the relevant time scale τ₀~h/Δ, where Δ is the average level spacing. It is found that the existence of necklace states is responsible for the second power-law behavior τ^-2, which has an extremely small distribution probability.