Ever wonder what an atom might sound like, if you could tap it like a tuning fork? Wonder no more, scientists say; they report they've managed just such a "tap" and recorded the result.
Researchers at Chalmers University of Technology in Gothenburg report they've interacted with an artificially constructed atom, hitting it with energy consisting of sound waves and getting something similar back.
Usually an atom charged with energy will emit a particle of light, a photon, but the atom created by the Chalmers researchers was configures to both absorb and emit energy in the form of a sound particle called a phonon.
"According to the theory, the sound from the atom is divided into quantum particles," says study first author Martin Gustafsson. "Such a particle is the weakest sound that can be detected."
With sound moving much more slowly than light, their "acoustic atom" creates entirely novel possibilities for managing and controlling quantum phenomena, the researchers say.
"Due to the slow speed of sound, we will have time to control the quantum particles while they travel" Gustafsson says. "This is difficult to achieve with light, which moves 100,000 times more quickly."
It's proof that light and electromagnetic radiation aren't the only forms of energy that can be emitted at the quantum level; sound can be too, the research team reports in the journal Physical Review A.
The finding could be one more step toward quantum computers, utilizing the power of sound to create incredibly quick data processor and electrical circuits.
"We have opened a new door into the quantum world by talking and listening to atoms", says Per Delsing, leader of the experimental research group. "Our long term goal is to harness quantum physics so that we can benefit from its laws, for example in extremely fast computers."
So what's the sound of their atom? The researchers say it's a D note, but at 20 times as high as the highest note playable on a piano, it's much too high-pitched for the human ear to detect.
Some experts not involved in the study were quick to pick up on the possibilities inherent in the work.
Using slow-moving sound in a quantum computer, rather than light or electromagnetic radiation, might seem a step backward, but it could be a good idea, says Steve Rolston of the Joint Quantum Institute at the University of Maryland.
"Normally slow is bad, but if it's slow enough you could switch something while (the phonon particle) is propagating," he says. "It gives you more possibilities."
