Space research yields high-tech reward

HIGH-TECH OPTICS--Sobolewski demonstrates how the single photon detector, housed inside the canister on the right that keeps the detector at a temperture near absolute zero, can detect infrared light. "The detector, developed through collaboration with Russian astronomers, efficiently and accurately measures infrared photon emissions."

niversity researchers from the Department of Electrical and Computer Engineering working in collaboration with Russian astronomers, have developed an extremely sensitive and accurate infrared detector that may offer a solution to a high-tech problem.

The new device, sensitive enough to detect single photons, can ferret out a misfiring transistor from the myriad on today's Pentium and PowerPC chips, allowing chip manufacturers to test billions of transistors on each chip more quickly and efficiently than previously possible.

Sobolewski

This unlikely marriage of American engineers and Russian astronomers was the result of a conference five years ago when Roman Sobolewski, professor of electrical and computer engineering at the University and co-creator of the device, met the team from the Moscow State Pedagogical University. The scientists discussed merging Russian technology with U.S. optical instrumentation and aiming it toward development of a completely new class of optical single-photon detectors.

"We were working on the photoresponse of superconductors and we contacted this group in Moscow that was using superconductors for radio astronomy," says Sobolewski. "The upper radio bands are essentially lower infrared bands, so we got together with the Moscow team and worked on putting their materials into our detector."

Initially, they devised a few experiments to test feasibility, and together won a small, international collaboration grant from Naval International Cooperative Opportunities in Science and Technology Program. The grant allowed Grigory Gol'tsman, professor of physics at the Moscow university, and two of his colleagues to visit Rochester.

"In the mid-nineties, the Internet bandwidth of the whole of Moscow was about the same as just our University," says Sobolewski. "We were working on this project with Grigory's team but we couldn't even send them e-mail with graphics to illustrate experimental results. Everything had to be put on paper and faxed."

The situation changed dramatically with a second grant from the North Atlantic Treaty Organization (NATO) Scientific and Environmental Affairs Division in Bruxelles, which covered both teams' travel expenses as well as the construction of a completely new Internet infrastructure for the Moscow group. That's when the research kicked into high gear.

The subsequent experiments showed that ultrathin strips of a metallic compound called niobium nitrite a millionth of a meter wide and only several atoms thick could detect visible and infrared photons. Inside a kind of thermos of liquid helium at a temperature near absolute zero, the strips, fabricated in Moscow, become a superconductor--able to conduct electricity without any of the resistance found in normal conductors like copper wires.

Sobolewski and his Russian colleagues have a patent pending for the device together with engineers from Schlumberger Semiconductor Solutions, a California company that builds testers for integrated circuits and sponsors the research through the University's Center for Electronic Imaging Systems (CEIS).

Sobolewski sees the superconducting single-photon optical detector making a difference in other fields such as space communications between Earth and Mars and quantum cryptographic applications, where bits of information are coded and transmitted as single photons, offering unconditionally secret, undecipherable communication.

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