title: Experimental demonstration of counterfactual quantum communication.
abstract: Quantum effects, besides offering substantial superiority in many tasks over classical methods, are also expected to provide interesting ways to establish secret keys between remote parties. A striking scheme called "counterfactual quantum cryptography" proposed by Noh [Phys. Rev. Lett. 103, 230501 (2009).] allows one to maintain secure key distributions, in which particles carrying secret information are seemingly not being transmitted through quantum channels. We have experimentally demonstrated, for the first time, a faithful implementation for such a scheme with an on-table realization operating at telecom wavelengths. To verify its feasibility for extension over a long distance, we have furthermore reported an illustration on a 1 km fiber. In both cases, high visibilities of more than 98% are achieved through active stabilization of interferometers. Our demonstration is crucial as a direct verification of such a remarkable application, and this procedure can become a key communication module for revealing fundamental physics through counterfactuals.
authors.affiliation: Hefei National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.forename: Lei
authors.initials: L
authors.lastname: Ju
authors.forename: Xiao-Lei
authors.initials: XL
authors.lastname: Liang
authors.forename: Shi-Biao
authors.initials: SB
authors.lastname: Tang
authors.forename: Guo-Liang Shen
authors.initials: GL
authors.lastname: Tu
authors.forename: Lei
authors.initials: L
authors.lastname: Zhou
authors.forename: Cheng-Zhi
authors.initials: CZ
authors.lastname: Peng
authors.forename: Kai
authors.initials: K
authors.lastname: Chen
authors.forename: Teng-Yun
authors.initials: TY
authors.lastname: Chen
authors.forename: Zeng-Bing
authors.initials: ZB
authors.lastname: Chen
authors.forename: Jian-Wei
authors.initials: JW
authors.lastname: Pan