A satellite-constellation based global quantum network could allow secure quantum communication between remote users worldwide. Such a constellation could be formed of micro- or even nanosatellites, which have the advantage of being more cost-effective than larger expensive spacecrafts. At the same time, the features of quantum communication impose a number of technical requirements that are more difficult to meet when using small satellites. Full-fledged quantum communication has been demonstrated with neither a micro- nor a nanosatellite so far. The authors took up this challenge and have developed a 6U CubeSat weighting 9.5 kg. The satellite is to be launched in 2023 and has already successfully passed all the pre-flight tests. The mission is not yet intended for fully quantum communication. Nevertheless, the authors are testing such key functional elements as polarization reference-frame synchronization and acquisition, pointing and tracking system on it. Besides that, the payload accommodates a full-duplex telecommunication system operating at a bit rate of 50 Mbit/s: an up- and a downlink at wavelengths of 808 and 850 nm. After the satellite is launched, the main goal to be achieved is to demonstrate stable connection between it and an optical ground station and carry out multiple communication sessions. In quantum communication, generating secret keys from raw measurement data implies two-way exchange of significant amount of information and therefore availability of a classical communication channel with a high bandwidth is one of the crucial things. In the following mission, which envisages an overall quantum key distribution system, we plan to use the free-space optical link for such an exchange of data, whereas the RF link will only be used for telemetry and telecommand.

中文翻译：

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矢量—利用小卫星进行量子密钥分发

基于卫星星座的全球量子网络可以实现全球远程用户之间的安全量子通信。这样的星座可以由微型甚至纳米卫星组成，其优点是比大型昂贵的航天器更具成本效益。同时，量子通信的特点提出了许多技术要求，而使用小型卫星更难以满足这些要求。迄今为止，无论是微米卫星还是纳米卫星都没有证明成熟的量子通信。作者接受了这一挑战，开发了一颗重 9.5 公斤的 6U 立方体卫星。该卫星将于2023年发射，目前已成功通过所有飞行前测试。该任务尚未用于完全量子通信。尽管如此，作者正在测试诸如偏振参考系同步以及其上的采集、指向和跟踪系统等关键功能元件。除此之外，有效负载可容纳以 50 Mbit/s 比特率运行的全双工电信系统：上行链路和下行链路的波长分别为 808 和 850 nm。卫星发射后，主要目标是验证卫星与光地面站的稳定连接并进行多次通信会话。在量子通信中，从原始测量数据生成密钥意味着大量信息的双向交换，因此具有高带宽的经典通信信道的可用性是至关重要的事情之一。在接下来的任务中，设想了一个整体的量子密钥分配系统，我们计划使用自由空间光学链路进行此类数据交换，而射频链路将仅用于遥测和遥控命令。