论文标题
真正的多方纠缠不是安全会议密钥协议的前提
Genuine multipartite entanglement is not a precondition for secure conference key agreement
论文作者
论文摘要
纠缠在量子密钥分布的安全性中起着至关重要的作用。如Curty等人（2004年）所示，只有在存在基于纠缠的协议的基于相应的基于纠缠的协议的描述时，才能获得秘密密钥。在这里，我们调查了纠缠量子键分布对多部分方案的作用，即会议关键协议。特别是，我们询问多方纠缠的最强形式，即真正的多部分纠缠，是建立会议密钥的必要条件。我们表明，令人惊讶的是，即使各方在协议的每一轮中共享双方态状态，也可以获得非零会议密钥。此外，我们将会议关键协议与纠缠证人联系起来，并表明可以将非零会议密钥解释为非线性纠缠证人，该证人检测到一类国家无法被通常的线性纠缠证人证人发现。
Entanglement plays a crucial role in the security of quantum key distribution. A secret key can only be obtained by two parties if there exists a corresponding entanglement-based description of the protocol in which entanglement is witnessed, as shown by Curty et al (2004). Here we investigate the role of entanglement for the generalization of quantum key distribution to the multipartite scenario, namely conference key agreement. In particular, we ask whether the strongest form of multipartite entanglement, namely genuine multipartite entanglement, is necessary to establish a conference key. We show that, surprisingly, a non-zero conference key can be obtained even if the parties share biseparable states in each round of the protocol. Moreover we relate conference key agreement with entanglement witnesses and show that a non-zero conference key can be interpreted as a non-linear entanglement witness that detects a class of states which cannot be detected by usual linear entanglement witnesses.
