A Quantum Leap for Computers

A Quantum Leap For Computers For years, computer scientists have dreamed about a machine that would be the endgame in computing's eternal quest for more speed and power - a device so powerful that it could untangle in seconds what would take today's quickest computer a million years to solve. One possible path toward that dream is to build a machine that runs on the power of quantum physics, an idea so promising and so out-there that it has been called the Holy Grail of computer science.

The latest group to take on that challenge is a team of UW-Madison engineers, including materials science Professor Max Lagally MS'65, PhD'68, electrical and computer engineering Professor Dan van der Weide, and physics Professors Robert Joynt and Mark Eriksson '92. The researchers have won a federal grant to begin building an engine for a superpowered machine known as a quantum computer. If they succeed, a working model could be finished within ten to thirty years.

The UW team is combining the theories of advanced physics with a unique environment for engineering and measuring the performance of the computer's "parts." Working at a scale much smaller than a grain of sand, the scientists are crafting quantum dots, which act like tiny boxes that hold electrons inside. Quantum dots could work like the logic gates of classical computers, but instead of relying on the zeroes and ones of binary code, a quantum computer would use the dots to hold and measure the spin state of electrons. The power of a quantum computer would be derived from a linked chain of thousands of dots.

Although scientists have been able to trap individual atoms before, making the links has proved difficult. The UW's team may be the first to create dots that can be assembled into long chains, a crucial step toward being able to construct working quantum computers. "That is what is so exciting," says Eriksson. "Here we are building a new type of quantum dot that hasn't been made before, and if we can do this successfully, the infrastructure is out there so that the technical community should be able to run with this."

If they come to exist, quantum computers could make possible a whole new array of tasks that are difficult for today's computers - things such as encryption or language translation. A quantum computer may be able to instantly translate foreign languages as they are spoken, something unthinkable for the most powerful models now.

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