English

Bulk universality and quantum unique ergodicity for random band matrices in high dimensions

Probability 2023-10-26 v4

Abstract

We consider Hermitian random band matrices H=(hxy)H=(h_{xy}) on the dd-dimensional lattice (Z/LZ)d(\mathbb Z/L \mathbb Z)^d, where the entries hxy=hyxh_{xy}=\overline h_{yx} are independent centered complex Gaussian random variables with variances sxy=Ehxy2s_{xy}=\mathbb E|h_{xy}|^2. The variance matrix S=(sxy)S=(s_{xy}) has a banded profile so that sxys_{xy} is negligible if xy|x-y| exceeds the band width WW. For dimensions d7d\ge 7, we prove the bulk eigenvalue universality of HH under the condition WL95/(d+95)W \gg L^{95/(d+95)}. Assuming that WLϵW\geq L^\epsilon for a small constant ϵ>0\epsilon >0, we also prove the quantum unique ergodicity for the bulk eigenvectors of HH and a sharp local law for the Green's function G(z)=(Hz)1G(z)=(H-z)^{-1} up to ImzW5L5d{\mathrm{Im}} \, z \gg W^{-5}L^{5-d}. The local law implies that the bulk eigenvector entries of HH are of order O(W5/2Ld/2+5/2){\mathrm{O}}(W^{-5/2}L^{-d/2+5/2}) with high probability.

Keywords

Cite

@article{arxiv.2207.14533,
  title  = {Bulk universality and quantum unique ergodicity for random band matrices in high dimensions},
  author = {Changji Xu and Fan Yang and Horng-Tzer Yau and Jun Yin},
  journal= {arXiv preprint arXiv:2207.14533},
  year   = {2023}
}

Comments

72 pages. Accepted by Annals of Probability