Efficient Use of Quantum Resources for the Transmission of a Reference Frame
Giulio Chiribella, Giacomo Mauro D’Ariano, Paolo Perinotti, Massimiliano Federico Sacchi · Physical Review Letters · 2004
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.