Quantum Institute for Light and Atoms, School of Physics and Material Science, East China Normal University, Shanghai, 200062, China.
School of Physics and Astronomy, and Tsung-Dao Lee Institute, Shanghai Jiao Tong University, Shanghai, 200240, China.
Nat Commun. 2019 Jan 11;10(1):148. doi: 10.1038/s41467-018-08118-5.
Quantum memories are essential for quantum information processing. Techniques have been developed for quantum memory based on atomic ensembles. The atomic memories through optical resonance usually suffer from the narrow-band limitation. The far off-resonant Raman process is a promising candidate for atomic memories due to broad bandwidths and high speeds. However, to date, the low memory efficiency remains an unsolved bottleneck. Here, we demonstrate a high-performance atomic Raman memory in Rb vapour with the development of an optimal control technique. A memory efficiency of above 82.0% for 6 ns~20 ns optical pulses is achieved. In particular, an unconditional fidelity of up to 98.0%, significantly exceeding the no-cloning limit, is obtained with the tomography reconstruction for a single-photon level coherent input. Our work marks an important advance of atomic memory towards practical applications in quantum information processing.
量子存储器对于量子信息处理至关重要。已经开发出基于原子集合的量子存储器技术。通过光学共振的原子存储器通常受到窄带限制。由于带宽宽、速度快，远离共振的喇曼过程是原子存储器的一个很有前途的候选方案。然而，迄今为止，低存储效率仍然是一个未解决的瓶颈。在这里，我们通过开发最佳控制技术，在 Rb 蒸汽中展示了一种高性能的原子喇曼存储器。对于 6 ns~20 ns 的光脉冲，存储效率超过 82.0%。特别是，通过对单光子相干输入的层析重建，获得了高达 98.0%的无条件保真度，显著超过了无克隆极限。我们的工作标志着原子存储器朝着量子信息处理的实际应用迈出了重要的一步。
