Using a few ultracold ions, intense lasers and some electrodes, researchers have built the first programmable quantum computer. The new system, described in a paper to be published in Nature Physics, flexed its versatility by performing 160 randomly chosen processing routines.
Earlier versions of quantum computers have been largely restricted to a narrow window of specific tasks. To be more generally useful, a quantum computer should be programmable, in the same way that a classical computer must be able to run many different programs on a single piece of machinery.
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Researchers led by David Hanneke of the National Institute of Standards and Technology in Boulder, Colo., based their quantum computer on two beryllium ions chilled to just above absolute zero. These ions, trapped by an electromagnetic field on a gold-plated alumina chip, formed the quantum bits, or qubits, analogous to the bits in regular computers represented by 0s and 1s. Short laser bursts manipulated the beryllium ions to perform the processing operations, while nearby magnesium ions kept the beryllium ions cool and still.
Hanneke and colleagues chose 160 programs for the quantum computer to run. “We picked them, quite literally, at random,” Hanneke says. “We really wanted to sample all possible operations.”
The researchers ran each program 900 times. On average, the quantum computer operated accurately 79 percent of the time, the team reported in their paper, which was published online November 15. “Getting this kind of control over a quantum system is really interesting from a physics perspective,” Hanneke says.
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