Experimental transmission of quantum digital signatures over 90-km of   installed optical fiber using a differential phase shift quantum key   distribution system
  Quantum digital signatures apply quantum mechanics to the problem of guaranteeing message integrity and non-repudiation with information-theoretical security, which are complementary to the confidentiality realized by quantum key distribution. Previous experimental demonstrations have been limited to transmission distances of less than 5-km of optical fiber in a laboratory setting. Here we report the first demonstration of quantum digital signatures over installed optical fiber as well as the longest transmission link reported to date. This demonstration used a 90-km long differential phase shift quantum key distribution system to achieve approximately one signed bit per second - an increase in the signature generation rate of several orders of magnitude over previous optical fiber demonstrations. 
Robert J. Collins, Ryan Amiri, Mikio Fujiwara, Toshimori Honjo, Kaoru   Shimizu, Kiyoshi Tamaki, Masahiro Takeoka, Erika And...
quant-ph