Quantum state engineering with ququarts: Application for deterministic QKD protocol A. P. Shurupov, S. S. Straupe, S. P. Kulik, M. Gharib and M. R. B. Wahiddin EPL, 87 1 (2009) 10008 Published online: 24 July 2009 DOI: 10.1209/0295-5075/87/10008