Fundamentals of Quantum Communication through Atmospheric Channels

本次项目延期的主要目的是在项目一期所学知识的基础上，完成对“大气信道量子通信原理”的理论理解。这项任务需要对不同湍流条件和各种通信场景下的大气量子信道进行一般性的理论描述，这将包括与实验组的密切合作。在这方面，我们计划模拟具有中强湍流的城市大气量子通道。此外，我们打算描述在非均匀强湍流中的垂直和上升传播路径。这些路径对于描述卫星介导的量子通信至关重要，并允许人们实现全球量子通信网络。为了建立优化的通信协议，我们考虑了大气信道的时间特性。这将使我们有可能在最有利的时间间隔（当大气具有高透射率时）传输光信号。利用大气通道的优势确保了光的量子特性的高保真传输，如压缩、纠缠等。这将为建立全球自由空间量子通信网络铺平道路。

The main purpose of the proposed project prolongation is to accomplish the theoretical understanding of the "Fundamentals of Quantum Communication through Atmospheric Channels", based on the knowledge gained during the first period of the project. This task requires a general theoretical description of atmospheric quantum channels for different turbulence conditions and various communication scenarios, which will include a close cooperation with experimental groups. In this connection we plan to model the intracity atmospheric quantum channels with moderate-to-strong turbulence. Furthermore, we intend to describe the vertical and elevated propagation paths in inhomogeneous strong turbulence. Such paths are crucial for the description of the satellite-mediated quantum communication and allows one to accomplish global quantum communication networks. In order to establish optimized communication protocols we consider the temporal characteristics of the atmospheric channels. This will give us the possibility to post-select the optical signal, which is transmitted during the most favorable time intervals, when the atmosphere has a high transmittance. The exploitation of advantages of atmospheric channels ensures a high-fidelity transfer of quantum properties of light, such as squeezing, entanglement, and others. This shall pave the way to establish global free-space quantum communication networks.