论文标题
自由空间量子通信的限制和安全性
Limits and Security of Free-Space Quantum Communications
论文作者
论文摘要
自由空间量子通信的研究需要量子信息理论，光学和湍流理论的工具。在这里，我们结合了这些工具，以通过自由空间链路绑定钥匙和纠缠分布的最终速率，在这种链接中，量子系统的传播通常受衍射，大气消灭，湍流，指向误差和背景噪声的影响。除了建立最终限制外，我们还表明，通过合适的（试点引导和后选择后的）相干状态协议可实现的可组合秘密速率，足够接近这些限制，因此显示了自由空间通道对高速量子量子密钥分布的适用性。我们的工作提供了分析工具，可以在一般条件下评估相干州协议的可组合有限尺寸的安全性，从稳定通信通道的标准假设（基于光纤的连接中的典型）到褪色通道的更具挑战性的场景（如自由空间链接中的典型情况）。
The study of free-space quantum communications requires tools from quantum information theory, optics and turbulence theory. Here we combine these tools to bound the ultimate rates for key and entanglement distribution through a free-space link, where the propagation of quantum systems is generally affected by diffraction, atmospheric extinction, turbulence, pointing errors, and background noise. Besides establishing ultimate limits, we also show that the composable secret-key rate achievable by a suitable (pilot-guided and post-selected) coherent-state protocol is sufficiently close to these limits, therefore showing the suitability of free-space channels for high-rate quantum key distribution. Our work provides analytical tools for assessing the composable finite-size security of coherent-state protocols in general conditions, from the standard assumption of a stable communication channel (as is typical in fiber-based connections) to the more challenging scenario of a fading channel (as is typical in free-space links).
