Dahm's quantum bit could drive next-generation computers

CLEVELAND -- A tiny but mighty quantum computer, the size of a millimeter, may be part of a new generation of super-fast computers.

Arnold Dahm, Institute Professor of Physics at Case Western Reserve University, has received one of 62 large Information Technology Research grants from the National Science Foundation for more than $1 million and up to five years of support.

Dahm will develop quantum bit technology and study how it works as the ground work for building the first computer of this type. He is receiving with approximately $2.47 million to support work on "Quantum computing using electrons on helium films." The project focuses on making a quantum bit, the smallest unit of storage in a quantum computer.

Joining Dahm are physicists John Goodkind from the University of California at San Diego and Mark Dykman from Michigan State.

Dahm's project comes under the funding area of revolutionary computing in the NSF's new initiative to build U.S. leadership in the field of information technology.

The $90 million IRT initiative also emphasizes software, making computer networks faster and more universally accessible, information management, human-computer interfaces, advanced computational science, education and the workforce, and social or economic implications of information technology. "This initiative will help strengthen America's leadership in a sector that has accounted for one-third of the U.S. economic growth in recent years," says President Bill Clinton.

Dahm has considerable experience experimenting with electrons on helium, and has interacted professionally with Dykman and Philip Platzman from Lucent Technology. Platzman, along with Dykman, envisioned the system Dahm will use in the quantum computer.

"The theorists tell us it can work, but as an experimentalist, I want to put their ideas to a test to develop and invent new quantum bits-also known as qubits," says Dahm.

Over the next five years, the collaboration expects to develop this new qubit and put together as many as five qubits to understand how they interact as a system.

One qubit is comprised of a tiny metallic dot, less than one-millionth of meter in size. To understand the scale of how tiny these qubits are, Dahm says, approximately one million would fit on the end of pin head.

The dot is anchored to a plastic surface that is coated with a thin layer of helium, with electrons floating about it.

He adds this is one of the most difficult of systems proposed, because it must also operate in extremely low temperatures at almost absolute zero, which is -459.6� F.

"The low temperature is to make sure that if this qubit is in a given state, it will stay there for 10 microseconds-long enough to carry out calculations and transfer information," explains Dahm. The low temperature state will also require special refrigeration for storage, taking the computer out of the realm of the average computer users, but making it possible for use by government groups or corporations who want to secure private information.

This quantum computer has not been built yet, so it is difficult to predict all its uses, says Dahm. The quantum computer's unique way of decoding information is likened to putting lots of parallel computers together. "It is extremely fast, and it can solve huge problems that classical computers cannot solve," says Dahm. Among these problems is the ability to factor large numbers into primes (those that cannot be divided by other numbers) of as many as 40 digits for security purposes. Dahm sees the desktop computer linked to this quantum computer, which is controlling operations. He speculates that initially the primary use will be serving as a gatekeeper to secure computer systems, as well as to prevent breaking codes like those banks use in communicating with customers through the Internet or the Department of Defense uses to run its defense systems.