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Proceedings Paper

Quantum key distribution in a multi-user network at gigahertz clock rates
Author(s): Veronica Fernandez; Karen J. Gordon; Robert J. Collins; Paul D. Townsend; Sergio D. Cova; Ivan Rech; Gerald S. Buller
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Paper Abstract

In recent years quantum information research has lead to the discovery of a number of remarkable new paradigms for information processing and communication. These developments include quantum cryptography schemes that offer unconditionally secure information transport guaranteed by quantum-mechanical laws. Such potentially disruptive security technologies could be of high strategic and economic value in the future. Two major issues confronting researchers in this field are the transmission range (typically <100km) and the key exchange rate, which can be as low as a few bits per second at long optical fiber distances. This paper describes further research of an approach to significantly enhance the key exchange rate in an optical fiber system at distances in the range of 1-20km. We will present results on a number of application scenarios, including point-to-point links and multi-user networks. Quantum key distribution systems have been developed, which use standard telecommunications optical fiber, and which are capable of operating at clock rates of up to 2GHz. They implement a polarization-encoded version of the B92 protocol and employ vertical-cavity surface-emitting lasers with emission wavelengths of 850 nm as weak coherent light sources, as well as silicon single-photon avalanche diodes as the single photon detectors. The point-to-point quantum key distribution system exhibited a quantum bit error rate of 1.4%, and an estimated net bit rate greater than 100,000 bits-1 for a 4.2 km transmission range.

Paper Details

Date Published: 7 July 2005
PDF: 8 pages
Proc. SPIE 5840, Photonic Materials, Devices, and Applications, (7 July 2005); doi: 10.1117/12.608650
Show Author Affiliations
Veronica Fernandez, Heriot-Watt Univ. (United Kingdom)
Karen J. Gordon, Heriot-Watt Univ. (United Kingdom)
Robert J. Collins, Heriot-Watt Univ. (United Kingdom)
Paul D. Townsend, Univ. College Cork (Ireland)
Sergio D. Cova, Politecnico di Milano (Italy)
Ivan Rech, Politecnico di Milano (Italy)
Gerald S. Buller, Heriot-Watt Univ. (United Kingdom)

Published in SPIE Proceedings Vol. 5840:
Photonic Materials, Devices, and Applications
Goncal Badenes; Derek Abbott; Ali Serpenguzel, Editor(s)

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