U. scientist makes computing breakthrough

A University of Utah physicist and his team have made a breakthrough that could pave the way to quantum computing, in which computers can calculate many billions of times faster than they do now.

The researcher is Christoph Boehme, assistant professor of physics at the U., whose paper on the discovery ran in the Nov. 19 issue of Nature Physics.

If quantum computing becomes practical, it would involve one of the strangest phenomena in physics, the indeterminate nature of energy and matter at the tiniest scales. The technicalities are complex, but the outcome is that if the "spin" of atoms in a quantum computer could be read, a computer using 64 quantum bits in its calculations would be "2 to the 64th power faster, or about 18 billion billion times faster" than a 64-bit computer of today, the U. noted in a press release.

"Note: billion billion is correct," the release adds in parentheses.

The project involved embedding phosphorus atoms in a silicon matrix, then attaching electrodes that would measure a minute electrical current sent through the atoms. Without adjusting the atomic spin of the atoms, the current stayed steady, meaning the atoms' spin was random.

But when the material was cooled in liquid helium to -452 degrees, says the U., most of the phosphorus atoms' were changed so their spin pointed one direction. Then a magnetic field and microwave radiation were directed onto the sample, making the spin flip up and down "in concert for a few billionths of a second," it adds.

When that happened, the electrical current fluctuated accordingly. For the first time, the spin of a relatively few atoms — only about 10,000 — could be controlled and read.

An earlier experiment had used magnetic resonance to read spin, but that is a much cruder technique. It could read the overall result of 10 billion atoms combined. The improvement is 1 million times more sensitive.

The U. points out that to be able to read the spin of single atoms, another 10,000-fold improvement is needed. Later improvements may allow that.

"We made a breakthrough, that's important," Boehme said in a telephone interview. The team discovered a way to make the measurement with "very high sensitivity."

Still, he's quick to point out the research is in an early stage. Compared with development of the classical computer, he said, "we are right before the discovery of the abacus. There is no quantum computer."

Quantum computing may not be possible even in five or ten years. But in 15 or 20 years, the swift advancement in conventional computing power may slow to a halt. "At some point, this development comes to an end," he said.