猫状态的反事实分布

Noiseless attack and counterfactual security of quantum key distribution

Counterfactual quantum key distribution (QKD) enables two parties to share a secret key using an interaction-free measurement. Here, we point out that the efficiency of counterfactual QKD protocols can be enhanced by including non-counterfactual bits. This inclusion potentially gives rise to the possibility of noiseless attacks, in which Eve can gain knowledge of the key bits without introducing any errors in the quantum channel. We show how this problem can be resolved in a simple way that naturally leads to the idea of "counterfactual security", whereby the non-counterfactual key bits are in…

反事实量子密钥分发的实验验证

Experimental demonstration of counterfactual quantum key distribution

反事实量子密钥分发在对抗实际信号粒子的窃听方面具有天然的优势。当使用弱相干光源进行实际实现时，可以有效地防止光子数分裂攻击。我们在一个12.5 km长的量子信道的非平衡马赫-曾德尔干涉仪中实现了反事实的量子密钥分发，其条纹可见度高达96：4%。因此，我们获得了安全的密钥对噪声引起的攻击（如。真空攻击）和被动光子数分裂攻击。

反事实量子密钥分发中的探测器致盲攻击

Detector blinding attacks on counterfactual quantum key distribution

本研究针对反事实量子密钥分发协议，提出两种探测器致盲攻击方法，证明其安全性漏洞，并强调实验实现需加入明确对策以抵御此类攻击。

“反事实”量子协议

"Counterfactual" quantum protocols

分析了最近提出的协议的反事实性。提出了“反事实”的定义，有人认为，对不透明物体存在的无相互作用测量可以称为“反事实”，而对不存在这种物体的拟议“反事实”测量则不属于反事实。仅依赖于对象存在的测量的量子密钥分发协议是反事实的，但量子直接通信协议不是。因此，“反事实”这个名称对于最近通过量子直接通信传输量子态的“反事实”协议是不合适的。

On Joint Distributions, Counterfactual Values, and Hidden Variables in Relation to Contextuality

This paper deals with three traditional ways of defining contextuality: (C1) in terms of (non)existence of certain joint distributions involving measurements made in several mutually exclusive contexts; (C2) in terms of relationship between factual measurements in a given context and counterfactual measurements that could be made if one used other contexts; and (C3) in terms of (non)existence of ``hidden variables'' that determine the outcomes of all factually performed measurements. It is generally believed that the three meanings are equivalent, but the issues involved are not entirely trans…

半反事实密码学

Semi-counterfactual Cryptography

在反事实量子密钥分发（QKD）中，两个远程方可以通过阻塞而不是传输粒子来安全地共享随机偏振编码比特。我们提出了一个半反事实的QKD，即，一种是基于粒子的阻塞或非阻塞来共享和编码秘密位。因此，该方案是半反事实的，并且不基于偏振编码。与其他反事实方案和Goldenberg-Vaidman协议一样，但与BB84不同的是，编码状态是正交的，安全性最终来自单粒子非局域性。然而，与它们中的任何一个不同的是，生成的秘密比特在爱丽丝和鲍勃的联合行动之前是最不确定的。我们证明了协议的一般安全性，并详细研究了最一般的光子数保持非相干攻击。