Subject Categories: Physics
Published online 1 May 2013
Quantum key distribution (QKD) uses entangled photons to distribute secret keys between two parties. It is the only known method for establishing secure communication over an untrusted channel and has applications in large-scale networks with satellites and ground stations. However, the technology has a few operating limitations because photons can be lost to the environment.
Jianwei Pan and Chengzhi Peng at the University of Science and Technology of China in Shanghai and co-workers had previously developed a QKD system that could provide secure communication between two stationary points over an open-air distance of up to 100 kilometres. It was a great feat at the time, but the demonstration has little relevance to real-world applications as satellites are always in motion and transmit information through the atmosphere.
The researchers have therefore carried out three more demonstration experiments: one on a turntable, one in a hot-air balloon and one in a high-loss medium. Using their QKD system, they have successfully established secure communication over distances of 40 kilometres, 20 kilometres and 96 kilometres, respectively. The results demonstrate the potential of QKD technology and confirm its proper function in real-life situations.