We review the optimal protocols for aligning spatial frames using quantum systems. The communication problem addressed here concerns a type of information that cannot be digitalized. Asher Peres referred to it as "unspeakable information". We comment on his contribution to this subject and give a brief account of his scientific interaction with the authors.
Cite
@article{arxiv.quant-ph/0505142,
title = {Aligning Spatial Frames Through Quantum Channels},
author = {E. Bagan and R. Munoz-Tapia},
journal= {arXiv preprint arXiv:quant-ph/0505142},
year = {2007}
}