Portland, Ore. - A prototype quantum-key distribution system may move from lab to commercial systems as early as next year, NEC Corp. reports.
Company researchers have completed the prototype, NEC said, and the needed software is now being written.
NEC described its progress to the 30th European Conference on Optical Communication (www.ecoc.se).
At the conference, held last month in Stockholm, Sweden, NEC described how it overcame previously reported obstacles. It said researchers had successfully encoded, modulated and added a clock signal to their single-photon transmissions, achieving a sustained quantum-key distribution (QKD) rate of 100 kbits/second over a distance of about 25 miles. The researchers predicted that NEC will likely begin delivering commercial QKD systems based on their prototype by the end of 2005.
The development, based on the encoding of a single photon, builds on work NEC described in March, when it showcased a single-photon amplifier and optical delay line called the Planar Lightwave Circuit (PLC). The circuit was jointly developed with the Japan Science and Technology Agency's Exploratory Research for Advanced Technology and Japan's National Institute of Information and Communications Technology. Using the PLC, NEC researchers reported last month that they had achieved a better than 90-mile transmission of an unencoded, unmodulated photon without even a clock signal.
"NEC's quantum-cryptography research is accelerating with each new achievement, putting us ahead of the competition, thus allowing us to contribute to overall development in this field," said Kazuo Nakamura, senior manager at NEC's Fundamental and Environmental Research Laboratories.
The company had evaluated id Quantique SA's approach to a QKD system, which was demonstrated in 2002, but rejected that plug-and-play approach because it required an encryption key to be transmitted from a sender to a receiver and then back to the receiver, thereby halving the maximum possible distance of the system. "We found that the [plug-and-play] quantum-key generation rate was limited by the detector efficiency," said researchers Yoshihiro Nambu and Hideo Kosakaj in a 2003 report. "The maximum transmission distance of the secret keys was limited to about 70 kilometers [more than 40 miles]."
NEC achieved its 90-mile transmission by developing an alternative similar to the approach taken by MagiQ Technologies Inc., which also demonstrated a QKD system in 2002.
MagiQ, for its part, said it welcomed NEC's entry into the arena. "We think this is good news for the whole industry, in the sense that a large player is getting involved," said Bob Gelfond, founder and chief executive officer of MagiQ Technologies (New York). "It just shows that there really is a large worldwide market for quantum-encryption products."
The first worldwide quantum-key distribution system went online in 2003 as the World Internet Secure Key SA (WiseKey), formed in cooperation with the International Organization for the Security of Electronic Transactions. MagiQ announced successful end-to-end quantum communication in 2003 with its Navajo Security Gateway, which combined QKD with the data communications hardware necessary to use existing fiber-optic connections.
"We introduced the world's first commercial product a year ago, before many people were confident in the market," Gelfond said. "We are not overconfident in our ability to compete with NEC, but we do think our head start is a distinct advantage. We have already sold units and have begun to grow the market. We also have a very large portfolio of intellectual property to protect us."
MagiQ began marketing its turnkey quantum-encryption solution in Japan in February through a partnership with Nissho Electronics Corp., a Tokyo-based distributor that specializes in adapting foreign technologies to the requirements of the Japanese market.
"There is a big difference between a laboratory system that only distributes quantum keys and what you have to actually put into a commercial product where you have to meet more robust needs than a lab experiment," Gelfond said. "We're not just offering a quantum-key distribution, we offer a complete quantum-encryption data transmission solution that runs at 100 Mbits/second today, and will run at 1 Gbit/s by next year."
The National Institute of Standards and Technology also operates a complete end-to-end Quantum Communication Testbed that routinely exchanges quantum keys at rates of up to 1 Mbit/s over a 730-meter free-space link.
The prototype NEC described in Stockholm exchanges quantum keys at speeds of up to 100 kbits/s when transmitting them over commercial fiber-optic lines at distances of up to 25 miles. The company did not report its end-to-end quantum-encryption communication speed, but is concentrating on offering first a quantum-key distribution system that users can configure into their existing data communications system.
The NEC system was tested successfully in April at the company's System Platforms Research Laboratories in Tamagawa, Japan, Nakamura said. The company reported having overcome previous speed-related problems it had with the mirrors in its PLC.
The improvement, Nakamura said, was made possible by a Faraday mirror that accurately rotates the polarization of the photons it reflects by 90 degrees at temperatures between -5 degrees C and +70 degrees C.
NEC developed its system in cooperation with Japan's National Institute of Advanced Industrial Science and Technology. The company said it is developing the software necessary to release a commercial QKD product by the end of 2005.
The quantum-key distribution system examined by NEC was demonstrated by id Quantique SA in 2002. See www.eetimes.com/article/showArticle.jhtml?articleId=9900839.
MagiQ Technologies Inc. also demonstrated its QKD system in 2002. See /www.eetimes.com/at/news/OEG20021105S0019.
The first worldwide QKD system, the World Internet Secure Key SA (WiseKey), went online in 2003.
MagiQ Technologies successfully completed end-to-end quantum communication of QKD data over fiber-optic connections in 2003. See www.eet.com/article/showArticle.jhtml?articleId=16502446.
The National Institute of Standards and Technology operates an end-to-end Quantum Communication Testbed that can exchange quantum keys at rates of up to 1 Mbit/s over a 730-meter free-space link. See www.eet.com/article/showArticle.jhtml?articleId=44300008.