April 2006

EEEL Researchers Deliver World's Fastest Detector System for Quantum Cryptography

Quantum cryptography is the exchange of information using techniques whose security is determined by the laws of quantum mechanics rather than by mathematical complexity. Quantum mechanics offers the potential for secure communication because measurement of an unknown quantum system changes its state. As a consequence, accurate copying is impossible and changes caused by eavesdropping can be detected. In quantum cryptography, single photons are used to carry information, and the availability of a robust system depends on the development of fast and efficient sources and detectors for single photons.

EEEL researchers recently delivered a single photon detection system to BBN Technologies in Cambridge, Mass., which operates at 100 Mbits/sec (20 times faster than today's benchmark detector) and may have the potential to operate at 10 Gbits/sec. NIST built the device in collaboration with researchers at BBN, the University of Rochester, and Moscow Institute of Physics and Technology. The compact, rack-mounted detector system uses NIST-developed packaging and cooling technology, which efficiently couples the superconducting detector to a standard telecom fiber and allows operation at a temperature of ~3K without using liquid cryogens. The system now is operating in the Defense Advanced Research Projects Agency Quantum Network, sending quantum keys between BBN, Harvard University, and Boston University, under the streets of Cambridge and Boston, Mass.

EEEL programs currently are under way to further improve the detector performance and to apply the packaging and cooling technology to metrological instruments such as the Josephson-junction-based voltage standard.

CONTACT: Sae Woo Nam (EEEL, Boulder Division 815) 303-497-3148