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System Sets Speed Record for Quantum Encryption

From NIST Tech Beat: May 7, 2004

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Contact: Laura Ost

Physicist Joshua Bienfang
Physicist Joshua Bienfang sets up the NIST quantum key distribution system to receive a string of photons from colleagues stationed on the top floor of the NIST Administration Building (shown in the background.) The black instrument on the left is an 8-inch telescope used in collecting the incoming photons.
Photo by Gail Porter/NIST

The fastest known cryptographic system based on transmission of single photons—the smallest pulses of light—has been demonstrated by a team at the National Institute of Standards and Technology (NIST). The transmissions cannot be intercepted without detection, so that messages encrypted with the system can be kept secret.

The NIST “quantum key distribution” (QKD) system transmits a stream of individual photons to generate a verifiably secret key—a random series of digital bits, each representing0 or 1, used to encrypt messages—at a rate of 1 million bits per second (bps). This rate is about 100 times faster than previously reported systems of this type.

The demonstration, described in the May 3 issue of Optics Express, is the first major reported result from a new NIST testbed built to demonstrate quantum communications technologies and cryptographic key distribution. The testbed provides a measurement and standards infrastructure for research, testing, calibrations and technology development. Scientists tested the QKD system by generating an encryption key that could be sent back and forth between two NIST buildings that are 730 meters apart. They are using the testbed to develop data-handling techniques associated with this type of encryption.

Acadia Optronics LLC of Rockville, Md., consulted on the system design and hardware. Partial funding for the project was provided by the Defense Advanced Research Projects Agency.

For further information, see www.nist.gov/public_affairs/releases/quantumkeys.htm.