Efficient use of quantum resources for the transmission of a reference frame.
We propose a covariant protocol for transmitting reference frames encoded on N spins, achieving sensitivity N-2 without the need of a preestablished reference frame and without using entanglement between sender and receiver. The protocol exploits the use of equivalent representations that were overlooked in the previous literature.
Chiribella
G
G
QUIT Quantum Information Theory Group of the INFM, unità di Pavia, Dipartimento di Fisica A. Volta, via Bassi 6, I-27100 Pavia, Italy.
D'Ariano
G M
GM
Perinotti
P
P
Sacchi
M F
MF