量子通信网络主要由用于存储和操纵量子态的存储单元和联络存储单元之间的 信息载体构成。光子是信息载体的最佳选择,存储单元可以由固态材料或气态原子组成。 相对于二维空间,编码于一个高维空间的光子可以携带更大的信息量。若能够实现编码 于高维空间的量子态存储,则在增大存储单元存储容量的同时,还可以提高网络的信道 容量和传输效率,因而高维量子态的存储研究成为当前量子信息领域的热点领域。 简要回顾了国内外在高维量子态存储方面的进展,着重介绍了近期基于冷原子系综实 现单光子条件下高维量子态存储的突破性进展,提出了构建高维量子网络需要解决的关键问题。

Quantum network mainly consists of a memory used for storing and manipulating quantum information and an information carrier through which different memories can connect with others. Usually quantum information is encoded in a two-dimensional space of a photon, a robust information carrier. In this case, each photon can carry a bit of information. If the photon can live in a high-dimensional space, then the information carried by each photon could be increased significantly, the channel capacity of the network and the transmission efficiency would then be greatly enlarged. Moreover, storing high-dimensional states in quantum memory leads to significant improvements in storage capacity. After briefly introducing the progresses achieved at home and abroad, a significant breakthrough was reviewed towards the realization of high-dimensional quantum memories based on a cold atomic ensemble in detail, and some basic problems remaining were proposed which need to be solved to build the future quantum internet.