标题： 相干态量子密钥分发与外差检测的紧界 显示英文标题

标题： Tight bound on coherent states quantum key distribution with heterodyne detection

摘要： 我们提出了一种新的上限，用于直接和反向协调的相干态量子密钥分发协议中窃听者的相关信息，该协议使用外差检测。 该界限是通过对跨越每个物理高斯攻击的辛群变换的最大泄漏信息推导出来的。 我们展示了四种达到此界限的攻击，这表明此界限是紧的。 最后，我们将使用此新界限获得的保密密钥速率与同相检测速率进行了比较。 显示英文摘要

摘要： We propose a new upper bound for the eavesdropper's information in the direct and reverse reconciliated coherent states quantum key distribution protocols with heterodyne detection. This bound is derived by maximizing the leaked information over the symplectic group of transformations that spans every physical Gaussian attack on individual pulses. We exhibit four different attacks that reach this bound, which shows that this bound is tight. Finally, we compare the secret key rate obtained with this new bound to the homodyne rate.