Ding Dong-Sheng, Zhang Wei, Zhou Zhi-Yuan, Shi Shuai, Xiang Guo-Yong, Wang Xi-Shi, Jiang Yun-Kun, Shi Bao-Sen, Guo Guang-Can
Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei, Anhui 230026, China and Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
State Key Laboratory of Fire Science, University of Science & Technology of China, Hefei, Anhui 230026, China.
Phys Rev Lett. 2015 Feb 6;114(5):050502. doi: 10.1103/PhysRevLett.114.050502. Epub 2015 Feb 4.
Constructing a quantum memory for a photonic entanglement is vital for realizing quantum communication and network. Because of the inherent infinite dimension of orbital angular momentum (OAM), the photon's OAM has the potential for encoding a photon in a high-dimensional space, enabling the realization of high channel capacity communication. Photons entangled in orthogonal polarizations or optical paths had been stored in a different system, but there have been no reports on the storage of a photon pair entangled in OAM space. Here, we report the first experimental realization of storing an entangled OAM state through the Raman protocol in a cold atomic ensemble. We reconstruct the density matrix of an OAM entangled state with a fidelity of 90.3%±0.8% and obtain the Clauser-Horne-Shimony-Holt inequality parameter S of 2.41±0.06 after a programed storage time. All results clearly show the preservation of entanglement during the storage.
构建用于光子纠缠的量子存储器对于实现量子通信和网络至关重要。由于轨道角动量（OAM）固有的无限维度，光子的OAM具有在高维空间中对光子进行编码的潜力，从而能够实现高信道容量通信。处于正交偏振或光路中的纠缠光子已被存储在不同系统中，但尚无关于存储在OAM空间中纠缠的光子对的报道。在此，我们报告了首次通过拉曼协议在冷原子系综中存储纠缠OAM态的实验实现。我们以90.3%±0.8%的保真度重建了OAM纠缠态的密度矩阵，并在设定的存储时间后获得了2.41±0.06的克劳泽-霍恩-希莫尼-霍尔特不等式参数S。所有结果都清楚地表明了存储过程中纠缠的保持。
