基于四粒子纠缠态的两方量子密钥协商协议

量子密钥协商协议允许参与者通过公开的量子信道公平地协商一个共享秘密密钥，任何参与者的子集都不能独立地确定该共享密钥。它的安全性由量子力学原理保证，因此能够实现无条件安全，已经吸引了大量的关注。该文基于四粒子纠缠态和逻辑量子比特，提出了两个分别抵抗集体退相位噪声和集体旋转噪声的鲁棒的两方量子密钥协商协议。安全性分析证明这两个协议既能抵抗参与者和外部攻击，也能成功地抵抗两种特洛伊木马攻击。另外，这两个协议也能达到比较高的量子比特效率。

Two-Party Quantum Key Agreement Protocols Based on Four-Particle Entangled States

Quantum key agreement (QKA) protocols allow participants to negotiate a classical shared secret key fairly via public quantum channels. Furthermore, the shared key cannot be determined independently by any subset of the participants. Their security is assured by the quantum mechanics principles, so they can achieve unconditional security and have drawn considerable attention. Based on four-particle entangled states and logical qubits, two robust two-party quantum key agreement protocols against collective-dephasing noise and collective-rotation noise are proposed. The security analysis shows that the two protocols can not only resist against participant attacks and outsider attacks, but also resist against two kinds of Trojan horse attacks. Furthermore, the two protocols also achieve higher qubit efficiency.