Takeoka Masahiro, Seshadreesan Kaushik P, Wilde Mark M
National Institute of Information and Communications Technology, Koganei, Tokyo 184-8795, Japan.
Max Planck Institute for the Science of Light, Staudtstraße 2, 91058 Erlangen, Germany.
Phys Rev Lett. 2017 Oct 13;119(15):150501. doi: 10.1103/PhysRevLett.119.150501.
We consider quantum key distribution (QKD) and entanglement distribution using a single-sender multiple-receiver pure-loss bosonic broadcast channel. We determine the unconstrained capacity region for the distillation of bipartite entanglement and secret key between the sender and each receiver, whenever they are allowed arbitrary public classical communication. A practical implication of our result is that the capacity region demonstrated drastically improves upon rates achievable using a naive time-sharing strategy, which has been employed in previously demonstrated network QKD systems. We show a simple example of a broadcast QKD protocol overcoming the limit of the point-to-point strategy. Our result is thus an important step toward opening a new framework of network channel-based quantum communication technology.
我们考虑使用单发送方多接收方纯损耗玻色子广播信道进行量子密钥分发（QKD）和纠缠分发。我们确定了在发送方与每个接收方之间进行二分纠缠和秘密密钥蒸馏的无约束容量区域，前提是它们被允许进行任意的公共经典通信。我们结果的一个实际意义在于，所证明的容量区域相较于使用朴素时分复用策略可实现的速率有显著提高，而朴素时分复用策略已被用于先前展示的网络QKD系统中。我们展示了一个广播QKD协议的简单示例，该协议克服了点对点策略的限制。因此，我们的结果是朝着开启基于网络信道的量子通信技术新框架迈出的重要一步。
