Quantum Key Distribution Using a χ-Type State

Gan Gao

We propose a quantum key distribution protocol using entanglement swapping of χ-type state; in this protocol, Alice and Bob transmit a particle sequence to each other and perform χ-type state measurements. Alice's and Bob's roles are completely symmetric.

Norbert Lütkenhaus

Gan Gao

A quantum secure direct communication and quantum key distribution(QSDC-QKD) protocol based on χ-type entangled states was recently proposed by Hong et al. [J. Korean Phys. Soc. 61 , 1 (2012)]. By analyzing the protocol, we find that it is not secure; that is, the eavesdropper can eavesdrop on half of Bob’s secret messages and half of Alice’s secret keys without introducing any error.

Radha Pyari Sandhir

Hui-Juan Zuo, Wei Huang, Su‐Juan Qin

An arbitrated quantum signature scheme, which is mainly applied in electronic-payment systems, is proposed and investigated. The χ -type entangled states are used for quantum key distribution and quantum signature in this protocol. Compared with previous quantum signature schemes which also utilize χ -type entangled states, the proposed scheme provides higher efficiency. Finally, we also analyze its security under various kinds of attacks.

Masahiro Takeoka