Abstract
The or-exclusive function (xor) is one of the most important logical functions, and can be used in several protocols and algorithms, as encryption and error correction. This paper discusses several ways to implement the xor function, in a secure way using quantum communication, between users of a network. It is shown how to implement it using bipartite, tripartite and four-partite maximally entangled states, as well using an optical interferometer and strongly attenuated coherent states. Some protocols for secure communication using the xor, as quantum key distribution, are also proposed.
Acknowledgments
This work was supported by the Brazilian agency CNPq and FUNCAP.