Almost Ramanujan Expanders from Arbitrary Expanders via Operator Amplification

Fernando Granha Jeronimo, Tushant Mittal, Sourya Roy +1

We give an efficient algorithm that transforms any bounded degree expander graph into another that achieves almost optimal (namely, near-quadratic, $d\le 1/\hat{I}{»}^{2+o(1)}$) trade-of…