Quantum digital signature (QDS) is an approach to guarantee the nonrepudiation, unforgeability and transferability of a signature with the information-theoretical security. All previous experimental realizations of QDS relied on an unrealistic assumption of secure channels and the longest distance is only several kilometers. Here, we have experimentally demonstrated a recently proposed QDS protocol without any secure channel. Exploiting the decoy state modulation, we have successfully signed one bit message through up to 102 km optical fiber. Furthermore, we continuously run the system to sign the longer message "USTC" with 32 bit at the distance of 51 km. Our results pave the way towards the practical application of QDS.
@article{arxiv.1608.01086,
title = {Experimental Quantum Digital Signature over 102 km},
author = {Hua-Lei Yin and Yao Fu and Hui Liu and Qi-Jie Tang and Jian Wang and Li-Xing You and Wei-Jun Zhang and Si-Jing Chen and Zhen Wang and Qiang Zhang and Teng-Yun Chen and Zeng-Bing Chen and Jian-Wei Pan},
journal= {arXiv preprint arXiv:1608.01086},
year = {2017}
}