A. V. Burlakov, M. V. Chekhova, O. A. Karabutova, D. N. Klyshko, and S. P. Kulik, "Quantum ternary logic based on biphotons,"
in Quantum Electronics and Laser Science Conference, T. Gallagher, H. Van Driel, H. Gibbs, and D. Wineland, eds.,
OSA Technical Digest
(Optical Society of America, 2000), paper QThI31.