English

A random cover of a compact hyperbolic surface has relative spectral gap $\frac{3}{16}-\varepsilon$

Spectral Theory 2022-12-27 v4 Analysis of PDEs Probability

Abstract

Let XX be a compact connected hyperbolic surface, that is, a closed connected orientable smooth surface with a Riemannian metric of constant curvature -1. For each nNn\in\mathbf{N}, let XnX_{n} be a random degree-nn cover of XX sampled uniformly from all degree-nn Riemannian covering spaces of XX. An eigenvalue of XX or XnX_{n} is an eigenvalue of the associated Laplacian operator ΔX\Delta_{X} or ΔXn\Delta_{X_{n}}. We say that an eigenvalue of XnX_n is new if it occurs with greater multiplicity than in XX. We prove that for any ε>0\varepsilon>0, with probability tending to 1 as nn\to\infty, there are no new eigenvalues of XnX_n below 316ε\frac{3}{16}-\varepsilon. We conjecture that the same result holds with 316\frac{3}{16} replaced by 14\frac{1}{4}.

Keywords

Cite

@article{arxiv.2003.10911,
  title  = {A random cover of a compact hyperbolic surface has relative spectral gap $\frac{3}{16}-\varepsilon$},
  author = {Michael Magee and Frédéric Naud and Doron Puder},
  journal= {arXiv preprint arXiv:2003.10911},
  year   = {2022}
}

Comments

54 pages, 5 figures. Accepted for publication in GAFA. This version: journal version, incorporated referees' comments and added figures