Friday, December 17, 2010

The First Quantum Machine | Science/AAAS

The First Quantum Machine | Science/AAAS: A team of American physicists found a quicker route, as they reported in March. Instead of a beam, they fashioned a tiny diving board of aluminum nitride plated with aluminum that vibrated by getting thinner and thicker. As the doohickey hummed away at a very high frequency—a whopping 6 billion cycles per second—the “piezoelectric” material in it produced a warbling electric field that was easy to detect. Most important, through that field, the physicists managed to “couple” the mechanical device to an electronic one called a “phase qubit,” a ring of superconductor that itself has one low-energy and one high-energy quantum state.

Manipulating the qubit with microwaves, the researchers could use it to feed energy quanta into the oscillator or pull them out of it, as one might use an ATM to deposit a $20 bill to a bank account or withdraw one. First they showed that when they cooled the oscillator to a few hundredths of a degree they could get no quanta out of it. That meant it had to be in the cashed-out ground state, jiggling with only zero-point motion. The researchers then put the oscillator in a state with exactly one more quantum of energy. They even coaxed it into both states at once, so that it was literally moving two different amounts simultaneously.

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