EUGENE–Physicists at the University of Oregon have secured a $1.5 million federal grant to lead a three-university effort aimed at developing an advanced micro-processing device called a "quantum logic gate."

The quantum logic gate could allow for a number of dramatic technological advances, including efficient processing of encrypted information and the much heralded, but still speculative "quantum computer."

"Our three-year goal is to build one working quantum logic gate," says UO physicist Michael Raymer, who is the principal investigator overseeing the project which includes collaboration with researchers at the University of Colorado at Boulder and the University of Arizona. "The funding will enable us to build up a new laboratory dedicated to this work."

The quantum logic gate would put to use the peculiar qualities of quantum mechanics in the service of enhanced communications technologies.

"Quantum mechanics is often portrayed as weird behavior not understandable to us, almost a defect in nature," Raymer says. "But this is a case where we turn this on its head and try to use these weird quantum properties to do something useful."

Once a single logic gate is developed, it could be used to create quantum processing devices with capabilities that potentially could be used in practical applications. One application already conceived for quantum information processing is in the area of encryption–increasingly important with the explosion of e-commerce and growing concerns about on-line security.

In this conception, each bit of information would be encrypted on a single photon of light. This is in contrast to current state-of-the-art fiber-optic communication techniques in which each bit is encoded in a pulse of light made up of millions or billions of photons. Then devices built of numerous quantum logic gates might be used to process such encrypted information.

"Using this method, one can encrypt and decode messages so that there is no known way for eavesdroppers to break the encryption," Raymer says. "Quantum physics has surprisingly provided an answer to the problem of information security."

A second, though more speculative, use of the quantum logic gate would be as the building block for a "quantum computer" in much the same way as a transistor is the basic building block of today’s computer. Quantum computing has been recognized in the past five or so years as one of the most exciting areas of research, combining computer science theory and quantum physics.

"There are some very hard questions that need to be considered about the ultimate feasibility of this concept," Raymer says. "A few years ago physicists were quite skeptical, but very recent theoretical proofs about the possibility for operating these computers robustly in spite of noise, or errors, have astounded people."

Raymer notes that while the development of the quantum computer is still perhaps 20 years in the future, if one were ever built, it would be used "for certain special tasks and might operate thousands to millions of times faster than the largest parallel processor computer" available today.

These promising developments have, in part, led to rapid growth in the federal government’s interest in funding research in this area. The granting agencies for the UO’s quantum logic gate project are the Army Research Office and the National Science Foundation, and Raymer notes that project results will be published openly in the scientific literature.

Two other UO physicists, Peter Sercel and Hailin Wang, as well as student researchers will join Raymer in the project. The work will be carried out at the Oregon Center for Optics, a research center recently founded at the University of Oregon for the investigation of theoretical and experimental aspects of light, including lasers and other optical technology.

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