量子密钥分发（QKD）允许空间上分离的两方安全地生成密码密钥。第一个量子密钥分配协议是由C. H. Bennett和G.在1984年（BB84），描述了如何通过传输单个量子比特和交换经典认证信息来实现这一点。任何试图窃听协议的行为都会引入可被合法方检测到的错误。本文主要研究了基于BB84的EEQKD协议。在EEQKD中，BB84中单独发送的量子比特是纠缠的，因此不能直接提供给窃听者，在这个协议中，窃听者只能一个接一个地访问传输。对于给定的错误率，窃听者可以获得的最大信息使用一个简单的拦截重发（IR）攻击。在考虑量子比特丢失和量子信道噪声的实际情况下，估计了EEQKD的安全密钥生成速率。此外，还暴露了一个微妙的漏洞：对于量子位纠缠的特定设置，矛盾地证明在面对IR攻击时最有用，EEQKD减少到BB84。这项研究的一部分已发表在O。Ahonen等人，物理评论A 78，032314（2008）。
英文摘要：
Quantum key distribution (QKD) allows two spatially separated parties to securely generate a cryptographic key. The first QKD protocol, published by C. H. Bennett and G. Brassard in 1984 (BB84), describes how this is achieved by transmitting individual qubits and exchanging classical authenticated information. Any attempt to eavesdrop on the protocol introduces errors detectable by the legitimate parties.
This Licentiate Thesis studies the recently introduced EEQKD protocol which builds on BB84. In EEQKD, the qubits sent individually in BB84 are entangled and thus not directly available to an eavesdropper who is, in this protocol, provided only one-by-one access to the transmission. The maximal information an eavesdropper can gain using a straightforward intercept-resend (IR) attack, is obtained for a given error rate. The secure key generation rate of EEQKD is estimated in practical scenarios including qubit loss and quantum channel noise. In addition, an exquisite vulnerability is exposed: For a particular setting of qubit entanglement, paradoxically proving most useful in the face of an IR attack, EEQKD reduces to BB84.
Part of this research has been published in O. Ahonen et al., Physical Review A 78, 032314 (2008).
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University of Strasbourg and CNRS, CESQ and ISIS (UMR 7006), aQCess（斯特拉斯堡大学与法国国家科学研究中心，量子电子学与光谱学中心及强磁场综合光谱实验室）；Center for Engineered Quantum Systems, School of Mathematical and Physical Sciences, Macquarie University（麦考瑞大学数学与物理科学学院工程量子系统中心）
