title: Superbroadcasting of mixed states.
abstract: We derive the optimal universal broadcasting for mixed states of qubits. We show that the no-broadcasting theorem cannot be generalized to more than a single input copy. Moreover, for four or more input copies it is even possible to purify the input states while broadcasting. We name such purifying broadcasting superbroadcasting.
authors.affiliation: INFM, unità di Pavia and Dipartimento di Fisica A. Volta, QUIT Group, via Bassi 6, I-27100 Pavia, Italy. dariano@unipv.it
authors.forename: Giacomo Mauro
authors.initials: GM
authors.lastname: D'Ariano
authors.forename: Chiara
authors.initials: C
authors.lastname: Macchiavello
authors.forename: Paolo
authors.initials: P
authors.lastname: Perinotti