"Smaller" is the watchword when it comes to manufacturing the devices that make computers work. Scientists would like to make a quantum leap in miniaturization—and in computing power—by harnessing atoms to carry out calculations.

Classical Newtonian physics governs atoms en masse and describes the everyday cause-and-effect we observe in physical objects. But individual atoms and their constituents, such as electrons, obey the laws of quantum physics, where quirky behavior results as these particles jump back and forth between different energy states.

For decades, researchers have theorized that quantum effects could open the door to immensely powerful computers, if scientists can master the inherent complexities of this infinitely small world.

An SIUC physicist is working toward that day. Assistant professor Mark Byrd has received a five-year, $400,000 CAREER award from the National Science Foundation to study some of the fundamental problems in developing a working quantum computer. The grant will also fund a national conference on the topic to be held at SIUC.

Classical computers work by having a set of switches that can be in one of two positions: on or off, 1 or 0. But quantum computers would not be limited to this binary language. Instead, they would rely on the ability of atoms to represent a one, a zero, or virtually limitless positions in between—"qubits," rather than bits. A set of qubits could work on many calculations simultaneously. That parallelism would make quantum computers far more powerful than classical computers.

Such power would have broad application in the fields of encryption and security, in searching large databases, or in simulating quantum-mechanical systems. The latter capability would be immensely useful in chemistry, biology, physics, and other fields.

But first researchers must overcome many obstacles.

They have taken the first steps, stringing together 10 qubits that can perform calculations. But an actual quantum computer would involve at least several hundred such devices working in concert, Byrd says.

"The idea is for it to be scalable to larger systems. Each time we make a step we get to learn more about these systems and how they behave.

"But they do make errors," he says. "All of these systems are very susceptible to errors."

Byrd will investigate several ways to eliminate or compensate for the errors inherent in quantum computing. One of those methods will involve constructing codes very much like those written for classical computers to detect and correct errors.

He also will look at encoding the information carried by the qubits to make it less susceptible to outside interference or "noise," and ways to manipulate the "spin" of electrons to control that phenomenon.

Although much of Byrd's work is theoretical (equation-driven), he will work with experimentalists during parts of the grant project.