Duan Runyao, Shi Yaoyun
State Key Laboratory of Intelligent Technology and Systems, Tsinghua National Laboratory for Information Science and Technology, Department of Computer Science and Technology, Tsinghua University, Beijing 100084, China.
Phys Rev Lett. 2008 Jul 11;101(2):020501. doi: 10.1103/PhysRevLett.101.020501. Epub 2008 Jul 10.
Suppose that m senders want to transmit classical information to n receivers with zero probability of error using a noisy multipartite communication channel. The senders are allowed to exchange classical, but not quantum, messages among themselves, and the same holds for the receivers. If the channel is classical, a single use can transmit information if and only if multiple uses can. In sharp contrast, we exhibit, for each m and n with m>1 or n>1, a quantum channel of which a single use is not able to transmit information yet two uses can. This latter property requires and is enabled by quantum entanglement.
假设m个发送方希望通过一个有噪声的多方通信信道，以零错误概率向n个接收方传输经典信息。发送方之间允许交换经典消息，但不允许交换量子消息，接收方也是如此。如果信道是经典的，那么单次使用能够传输信息当且仅当多次使用能够传输信息。与之形成鲜明对比的是，对于每一对满足m>1或n>1的m和n，我们展示了一种量子信道，其单次使用无法传输信息，但两次使用却可以。后一种特性需要量子纠缠并由其实现。
