It's a problem most grade-school math students could solve: What are the factors of the number 15? Anyone who memorized multiplication tables as a kid, chanting the result of 3 times 5, can quickly tell you: 1, 3, 5, and 15.

And yet the computer science community was glowing late last month over news that a team of researchers at IBM's Almaden Research Center had designed a new machine capable of calculating 15's factors. The machine was a quantum computer, and no quantum computer had ever completed such a task.

Quantum computing is the holy grail of computer science. The classical computers of today—machines that operate according to the physics of the everyday world—run faster with each passing year, but very soon will reach a physical limit where increases in speed are no longer possible. But processing power can continue to improve through quantum computing, which relies on the physics associated with very small particles, such as atoms. Whereas the basic building blocks of a classical computer can perform only one operation at a time, the building blocks of a quantum computer, benefiting from the seemingly magical behavior of individual atoms, can perform multiple operations at once.

Led by Isaac L. Chuang, the Almaden team built a machine that utilized the quantum properties of a molecule consisting of seven atoms, each representing a bit—a fundamental unit of computing information. A 7-bit computer that does nothing more than solve a grade-school math problem hardly seems like a complex device, but the experiment indicates that scientists may one day build far more powerful quantum computers—machines capable of breaking the codes now used to protect the world's most important data.

"This experiment will help us learn about some of the problems that we'll encounter in the future, when we build truly complex quantum computers," says Fred Chong, a computer scientist at the University of California, Davis.