Xu Feihu, Zhang Yu-Zhe, Zhang Qiang, Pan Jian-Wei
Hefei National Laboratory for Physical Sciences at Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei 230026, China; CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; and Shanghai Research Center for Quantum Sciences, Shanghai 201315, China.
Phys Rev Lett. 2022 Mar 18;128(11):110506. doi: 10.1103/PhysRevLett.128.110506.
Device-independent quantum key distribution (QKD) can permit the superior security even with unknown devices. In practice, however, the realization of device-independent QKD is technically challenging because of its low noise tolerance. In the photonic setup, due to the limited detection efficiency, a large amount of the data generates from no-detection events which contain few correlations but contribute high errors. Here, we propose the device-independent QKD protocol with random postselection, where the secret keys are extracted only from the postselected subset of outcomes. This could not open the detection loophole as long as the entropy of the postselected subset is evaluated from the information of the entire set of data, including both detection and no-detection events. This postselection has the advantage to significantly reduce the error events, thus relaxing the threshold of required detection efficiency. In the model of collective attacks, our protocol can tolerate detector efficiency as low as 68.5%, which goes beyond standard security proofs. The results make a concrete step for the implementation of device-independent QKD in practice.
与设备无关的量子密钥分发（QKD）即使在设备未知的情况下也能提供卓越的安全性。然而，在实际应用中，由于其低噪声容忍度，实现与设备无关的QKD在技术上具有挑战性。在光子装置中，由于检测效率有限，大量数据来自未检测事件，这些事件相关性低但错误率高。在此，我们提出了一种具有随机后选择的与设备无关的QKD协议，其中仅从后选择的结果子集中提取秘密密钥。只要根据包括检测和未检测事件在内的整个数据集的信息评估后选择子集的熵，就不会打开检测漏洞。这种后选择具有显著减少错误事件的优点，从而放宽了所需检测效率的阈值。在集体攻击模型中，我们的协议能够容忍低至68.5%的探测器效率，这超越了标准的安全性证明。这些结果为在实际中实现与设备无关的QKD迈出了具体的一步。
