Multi-orbital frames through model spaces

Abstract

We characterize the normal operators A on ℓ2 and the elements ai∈ ℓ2, with 1 ≤ i≤ m, such that the sequence {Ana1,…,Anam}n≥0is a frame. The characterization makes strong use of the pseudo-hyperbolic metric of D and is given in terms of the backward shift invariant subspaces of H2(D) associated to finite products of interpolating Blaschke products.