Paper detail

Phase retrieval and norm retrieval

Phase retrieval has become a very active area of research. We will classify when phase retrieval by Parseval frames passes to the Naimark complement and when phase retrieval by projections passes to the orthogonal complements. We introduce a new concept we call norm retrieval and show that this is what is necessary for passing phase retrieval to complements. This leads to a detailed study of norm retrieval and its relationship to phase retrieval. One fundamental result: a frame $\{φ_i\}_{i=1}^M$ yields phase retrieval if and only if $\{Tφ_i\}_{i=1}^M$ yields norm retrieval for every invertible operator $T$.