On iterated powers of positive definite functions

Abstract

We prove that if $ρ$ is an adapted positive definite function in the Fourier--Stieltjes algebra $B(G)$ of a locally compact group $G$ with $\|ρ\|_{B(G)}=1$, then the iterated powers $(ρ^n)$ converge to zero in the weak* topology $σ(B(G) , C^*(G))$. Moreover, if $ρ$ is irreducible, we prove that $(ρ^n)$ as a sequence of u.c.p. maps on the group $C^*$-algebra converges to zero in the strong operator topology.