Appears in collection : 2025 - T1 - WS2 - Tempered representations and K-theory

A biunimodular function on a cyclic group of prime order is a function with constant modulus whose Fourier transform also has constant modulus. For instance gaussian functions are biunimodular. According to a theorem of Haagerup there are only finitely many biunimodular functions up to scalar. In this talk we will construct new biunimodular functions for all prime . The proof relies on symplectic geometry.