Researchers from NIST, NTT Corp., and Stanford University have successfully transmitted “quantum keys” over a 200-kilometer fiber-optic link, setting a new distance record for quantum key distribution (QKD). The experiment, conducted in a Stanford lab, used standard components and transmitted at telecommunications frequencies, demonstrating an approach for practical inter-city terrestrial quantum communications networks.
The demonstration achieved a new milestone by operating at a gigabit rate – transmitting at 10 billion light pulses per second – while producing secure keys. However, the rate of processed key production was lower due to the long distance involved. The experiment utilized ultrafast superconducting single-photon detectors developed in Russia, with packaging and cooling technology custom-made at NIST labs in Boulder, Colorado. These detectors have very low false count rates and superior timing resolution, enabling reliable detection of single photons – the smallest particles of light.
The project was supported by various organizations, including the Japan Science and Technology Agency, National Institute of Information and Communications Technology of Japan, MURI Center for Photonic Quantum Information Systems, Disruptive Technology Office, Defense Advanced Research Projects Agency, and NIST.
Source: https://www.nist.gov/news-events/news/2007/06/long-distance-record-quantum-keys-sent-200-kilometers
Keywords: Quantum, Key, Distribution, Photons, Encryption
