Koashi Masato, Preskill John
CREST Research Team for Interacting Carrier Electronics, School of Advanced Sciences, The Graduate University for Advanced Studies (SOKENDAI), Hayama, Kanagawa, 240-0193, Japan.
Phys Rev Lett. 2003 Feb 7;90(5):057902. doi: 10.1103/PhysRevLett.90.057902. Epub 2003 Feb 6.
We prove the security of the Bennett-Brassard (BB84) quantum key distribution protocol for an arbitrary source whose averaged states are basis independent, a condition that is automatically satisfied if the source is suitably designed. The proof is based on the observation that, to an adversary, the key extraction process is equivalent to a measurement in the sigma(x) basis performed on a pure sigma(z)-basis eigenstate. The dependence of the achievable key length on the bit error rate is the same as that established by Shor and Preskill [Phys. Rev. Lett. 85, 441 (2000)]] for a perfect source, indicating that the defects in the source are efficiently detected by the protocol.
我们证明了Bennett-Brassard（BB84）量子密钥分发协议对于任意源的安全性，该源的平均态与基无关，若源经过适当设计，则此条件会自动满足。证明基于这样的观察：对于敌手而言，密钥提取过程等同于对纯(\sigma(z))基本征态进行(\sigma(x))基测量。可实现的密钥长度与误码率的依赖关系，与Shor和Preskill [《物理评论快报》85, 441 (2000)]针对完美源所确定的相同，这表明该协议能有效检测源中的缺陷。
