Efficient use of quantum resources for the transmission of a reference frame

Abstract

A covariant protocol, aimed at transmitting reference frames encoded on N spins was proposed. The protocol exploited the use of equivalent representations that were overlooked previously. Using the protocol, sensitivity of N -2 was achieved without the need of a preestablished reference frame and without using entanglement between sender and receiver. It was shown that a relation between the present scheme and the entangled protocol existed with the role of entanglement played by equivalent representations.