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Bloch sphere, a geometrical representation of a two-level quantum system

The Globe and Mail

In Waterloo, a group of scientists with a room full of expensive equipment have achieved a herculean task: controlling a dozen atoms. What they're building with those 12 infinitesimally small particles are the early stages of a computing revolution.

Behold the quantum computer.

In physics, a quantum is the smallest part of a physical entity - at the atomic level, the most basic building block of everything around us. A quantum computer is essentially a traditional computer, but instead of bits - a 0 or a 1, the basic unit of digital information - it uses quantum bits, called qubits, composed of those tiny particles.

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The property of quantum systems that makes them so useful for building a computer is something called superposition. In a traditional computer, a bit can be a one or a zero. A qubit can also be a one or a zero, but importantly, it can also be both at the same time. That means two qubits can occupy four states at once, three qubits can occupy eight states, and so on. What's important isn't the numbers, but how fast they're growing - doubling with every new qubit. The computing growth factor is exponential, meaning that, in theory, it doesn't take very many qubits to create a computer more powerful than any traditional machine ever built.

"With this kind of system, you can solve problems that would be impossible to do with a classical computer," says Raymond Laflamme, director of the Institute of Quantum Computing at the University of Waterloo, one of the world's leading research hubs in the field.

The classic example of what a quantum computer can do involves encryption. Many of the world's encryption systems - protecting everything from e-mail messages to bank account information - rely on the difficulty of factoring large numbers. In fact, on a traditional computer, breaking the strongest current standards of such encryption would take longer than the age of the universe. With a quantum computer, however, such encryption systems are theoretically much easier to break.

Mr. Laflamme estimates it would take a 100-qubit computer to really tackle problems of such complexity. Right now, the researchers at the institute have succeeded in creating a machine of about 12. Still, Mr. Laflamme estimates we're about 15 or 20 years away from the kind of computer that could force the world to rethink how it keeps information secret.

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About the Author
U.S. business reporter

Omar El Akkad is The Globe's Western United States reporter, based in Portland, Oregon. He has been with The Globe since 2005. More

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