Superbroadcasting of mixed states.
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.
D'Ariano
Giacomo Mauro
GM
INFM, unità di Pavia and Dipartimento di Fisica A. Volta, QUIT Group, via Bassi 6, I-27100 Pavia, Italy. dariano@unipv.it
Macchiavello
Chiara
C
Perinotti
Paolo
P