Institutionen för Systemteknik, Linköpings Universitet, 581 83 Linköping, Sweden.
Department of Physics, Stockholm University, 106 91 Stockholm, Sweden.
Sci Adv. 2015 Dec 18;1(11):e1500793. doi: 10.1126/sciadv.1500793. eCollection 2015 Dec.
Photonic systems based on energy-time entanglement have been proposed to test local realism using the Bell inequality. A violation of this inequality normally also certifies security of device-independent quantum key distribution (QKD) so that an attacker cannot eavesdrop or control the system. We show how this security test can be circumvented in energy-time entangled systems when using standard avalanche photodetectors, allowing an attacker to compromise the system without leaving a trace. We reach Bell values up to 3.63 at 97.6% faked detector efficiency using tailored pulses of classical light, which exceeds even the quantum prediction. This is the first demonstration of a violation-faking source that gives both tunable violation and high faked detector efficiency. The implications are severe: the standard Clauser-Horne-Shimony-Holt inequality cannot be used to show device-independent security for energy-time entanglement setups based on Franson's configuration. However, device-independent security can be reestablished, and we conclude by listing a number of improved tests and experimental setups that would protect against all current and future attacks of this type.
基于能量-时间纠缠的光子系统已被提出，用于使用贝尔不等式来检验局域实在论。违反这个不等式通常也证明了设备无关量子密钥分发（QKD）的安全性，因此攻击者无法进行窃听或控制系统。我们展示了当使用标准雪崩光电二极管时，如何在能量-时间纠缠系统中规避这种安全测试，使得攻击者可以在不留下痕迹的情况下破坏系统。我们使用定制的经典光脉冲达到了高达 3.63 的贝尔值，伪造探测器效率达到 97.6%，甚至超过了量子预测。这是首次演示了一种可调节违反和高伪造探测器效率的违反伪造源。其影响是严重的：标准的 Clauser-Horne-Shimony-Holt 不等式不能用于基于 Franson 配置的能量-时间纠缠设置来显示设备无关的安全性。然而，设备无关的安全性可以重新建立，我们最后列出了一些改进的测试和实验设置，这些设置将能够抵御所有当前和未来的此类攻击。
