title: Entanglement between two uses of a noisy multipartite quantum channel enables perfect transmission of classical information.
abstract: 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.
authors.affiliation: 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. dry@tsinghua.edu.cn
authors.forename: Runyao
authors.initials: R
authors.lastname: Duan
authors.forename: Yaoyun
authors.initials: Y
authors.lastname: Shi