van Loock P, Ladd T D, Sanaka K, Yamaguchi F, Nemoto Kae, Munro W J, Yamamoto Y
National Institute of Informatics, 2-1-2 Hitotsubashi, Chiyoda-ku, Tokyo 101-8430, Japan.
Phys Rev Lett. 2006 Jun 23;96(24):240501. doi: 10.1103/PhysRevLett.96.240501. Epub 2006 Jun 19.
We describe a quantum repeater protocol for long-distance quantum communication. In this scheme, entanglement is created between qubits at intermediate stations of the channel by using a weak dispersive light-matter interaction and distributing the outgoing bright coherent-light pulses among the stations. Noisy entangled pairs of electronic spin are then prepared with high success probability via homodyne detection and postselection. The local gates for entanglement purification and swapping are deterministic and measurement-free, based upon the same coherent-light resources and weak interactions as for the initial entanglement distribution. Finally, the entanglement is stored in a nuclear-spin-based quantum memory. With our system, qubit-communication rates approaching 100 Hz over 1280 km with fidelities near 99% are possible for reasonable local gate errors.
我们描述了一种用于长距离量子通信的量子中继器协议。在该方案中，通过使用弱色散光与物质相互作用，并在各站点之间分配输出的明亮相干光脉冲，在信道的中间站点的量子比特之间创建纠缠。然后，通过零差检测和后选择以高成功率制备有噪声的电子自旋纠缠对。用于纠缠纯化和交换的本地门是确定性的且无需测量，基于与初始纠缠分布相同的相干光资源和弱相互作用。最后，将纠缠存储在基于核自旋的量子存储器中。对于合理的本地门误差，使用我们的系统，在1280公里的距离上，量子比特通信速率接近100赫兹，保真度接近99%是可能的。
