Quantum Secure Direct Communication by Using Three-Dimensional Hyperentanglement

Gü, Huang, Yu-Gai +4 more

Yu-Xiang Xiao, Lan Zhou, Wei Zhong +2 more

Fang-Zhou Wu, Guojian Yang, Haibo Wang +4 more

Jin Shi, Yan-Xiao Gong, Ping Xu +2 more

We propose two schemes for realizing quantum secure direct communication (QSDC) by using a set of ordered two-photon three-dimensional hyperentangled states entangled in two degrees of freedom (DOFs) as quantum information channels. In the first scheme, the photons from Bob to Alice are transmitted only once. After insuring the security of the quantum channels, Bob encodes the secret message on his photons. Then Alice performs single-photon two-DOF Bell bases measurements on her photons. This scheme has better security than former QSDC protocols. In the second scheme, Bob transmits photons to Alice twice. After insuring the security of the quantum channels, Bob encodes the secret message on his photons. Then Alice performs two-photon Bell bases measurements on each DOF. The scheme has more information capacity than former QSDC protocols.

Tie-Jun Wang, Tao Li, Fang-Fang Du +1 more

We present a quantum hyperdense coding protocol with hyperentanglement in polarization and spatial-mode degrees of freedom of photons first and then give the details for a quantum secure direct communication (QSDC) protocol based on this quantum hyperdense coding protocol. This QSDC protocol has the advantage of having a higher capacity than the quantum communication protocols with a qubit system. Compared with the QSDC protocol based on superdense coding with d-dimensional systems, this QSDC protocol is more feasible as the preparation of a high-dimension quantum system is more difficult than that of a two-level quantum system at present.

Yan Xia, Qing-Qin Chen, Jie Song +1 more

The entangled states analysis is a very important element for quantum information. It is impossible to unambiguously distinguish the three-photon Greenberger–Horne–Zeilinger (GHZ) states in polarization, resorting to linear optical elements only. Here, we propose an efficient scheme to complete three-photon hyperentangled GHZ states analysis (HGSA) with the help of the cross-Kerr nonlinearity. The three-photon HGSA scheme can also be generalized to N-photon hyperentangled GHZ states analysis. We discuss the application of the HGSA in the quantum secure direct communication (QSDC) with polarization and spatial-mode degrees of freedom. The results show that the HGSA not only increase the channel capacity but also ensure the unconditional security in long-distance quantum communication.