A two-step quantum secure direct communication protocol with hyperentanglement
Gu Bin(顾斌), Huang Yu-Gai(黄余改), Fang Xia(方夏), and Zhang Cheng-Yi(张成义)
Chin. Phys. B . 2011, (10): 100309 -100309 .  DOI: 10.1088/1674-1056/20/10/100309