Vazirani Umesh, Vidick Thomas
University of California, Berkeley, California 94720, USA.
California Institute of Technology, Pasadena, California 91125, USA.
Phys Rev Lett. 2014 Oct 3;113(14):140501. doi: 10.1103/PhysRevLett.113.140501. Epub 2014 Sep 29.
Quantum cryptography promises levels of security that are impossible to replicate in a classical world. Can this security be guaranteed even when the quantum devices on which the protocol relies are untrusted? This central question dates back to the early 1990s when the challenge of achieving device-independent quantum key distribution was first formulated. We answer this challenge by rigorously proving the device-independent security of a slight variant of Ekert's original entanglement-based protocol against the most general (coherent) attacks. The resulting protocol is robust: While assuming only that the devices can be modeled by the laws of quantum mechanics and are spatially isolated from each other and from any adversary's laboratory, it achieves a linear key rate and tolerates a constant noise rate in the devices. In particular, the devices may have quantum memory and share arbitrary quantum correlations with the eavesdropper. The proof of security is based on a new quantitative understanding of the monogamous nature of quantum correlations in the context of a multiparty protocol.
量子密码学有望实现经典世界中无法复制的安全级别。即使协议所依赖的量子设备不可信，这种安全性能否得到保证？这个核心问题可以追溯到20世纪90年代初，当时首次提出了实现设备无关量子密钥分发的挑战。我们通过严格证明埃克特原始基于纠缠的协议的一个微小变体针对最一般（相干）攻击的设备无关安全性来应对这一挑战。由此产生的协议很强大：虽然只假设设备可以用量子力学定律建模，并且在空间上彼此隔离且与任何对手的实验室隔离，但它实现了线性密钥率并容忍设备中的恒定噪声率。特别是，设备可能具有量子存储器，并与窃听者共享任意量子关联。安全性证明基于对多方协议背景下量子关联一夫一妻制性质的新定量理解。
