The spatial modes of light, carrying a quantized amount of orbital angular momentum (OAM), is one of the excellent candidates that provides access to high-dimensional quantum states, which essentially makes it promising towards building high-dimensional quantum networks. Quantum memory with efficiency above 50% is an essential condition for beating the no-cloning limit or in the one-way quantum computation. However, up till now, the highest storage efficiencies achieved for OAM states are below 30%, which is an obstacle towards practical applications. In this paper, we report the storage and retrieval of photonic qubits encoded with OAM state in an elongated cold rubidium atomic ensemble, achieving a storage efficiency around 65% with an average conditional fidelity above 98%. Our work constitutes an efficient node that is needed towards high dimensional and large scale quantum networks.

光的空间模式携带量化的轨道角动量 (OAM)，是提供高维量子态访问的优秀候选者之一，这从本质上使其有望构建高维量子网络。效率高于 50% 的量子存储器是突破不可克隆限制或单向量子计算的必要条件。然而，到目前为止，OAM 状态实现的最高存储效率低于 30%，这是实际应用的障碍。在本文中，我们报告了在细长的冷铷原子系综中使用 OAM 状态编码的光子量子位的存储和检索，实现了约 65% 的存储效率，平均条件保真度高于 98%。