Relaxation of coherent states in a two-qubit NMR quadrupole system - Sarthour, R. S.; Azevêdo, Eduardo Ribeiro de; Bonk, F. A.; Vidoto, Edson Luiz Gea; Bonagamba, Tito José; Guimarães, A. P.; Freitas, J. C. C.; Oliveira, I. S. (Physical Review A, 2003)