2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/120943To any complex Hadamard matrix we associate a quantum permutation group. The correspondence is not one-to-one, but the quantum group encapsulates a number of subtle properties of the matrix. We investigate various aspects of the construction: compatibility to product operations, characterization of matrices which give usual groups, explicit computations for small matrices.22 pagesOperator Algebras46L65 (05B20, 46L37)text