The breakthrough of this year from Science

Near the end of this year, one may ask, what is the breakthrough in science this year ? Every one may have his own answer. The one from Science is the achievement of a tiny quantum vibrator that is less the width of a hair. This article reviews why it is a breakthrough:

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.

The ingenuity in this scheme lay in the design of the oscillator and the use of a qubit to control it. In fact, in 2009, the team used a phase qubit to feed quanta into a long strip of superconducting metal that would ring with microwaves much as an organ pipe rings with sounds. Once they worked the kinks out, they replaced the microwave cavity with their clever mechanical oscillator, a move that had other physicists slapping their foreheads for not having seen it coming.