The completely delocalized region of the Erdős-Rényi graph

Abstract

We analyse the eigenvectors of the adjacency matrix of the Erdős-Rényi graph on $N$ vertices with edge probability $\frac{d}{N}$. We determine the full region of delocalization by determining the critical values of $\frac{d}{\log N}$ down to which delocalization persists: for $\frac{d}{\log N}>\frac{1}{\log 4-1}$ all eigenvectors are completely delocalized, and for $\frac{d}{\log N}>1$ all eigenvectors with eigenvalues away from the spectral edges are completely delocalized. Below these critical values, it is known [arXiv:2005.14180, arXiv:2106.12519] that localized eigenvectors exist in the corresponding spectral regions.

10 pages, 1 figure