Researchers at Columbia University and Sweden’s Chalmers University of Technology claims that they have “captured” the sound a single atom, it creates when it is in its excited stage—a single “phonon,” which is called as the softest sound possible.
The interaction between atoms and light has been the subject for research for long in the field of quantum optics. Now for the first time, scientists have figured out how to get their artificial atom to emit and absorb energy in the form of sound particles.
“According to the theory, the sound from the atom is divided into quantum particles,” the first author of the article, Martin Gustafsson said. “Such a particle is the weakest sound that can be detected.”
Photons are always utilized in quantum experiments, but their fast speed have made them a tough nut to crack. Phonons move 10^5 slower and thus could help in making quantum communication easier.
“We have opened a new door into the quantum world by talking and listening to atoms,”said the lead of the experimental research group, Per Delsing.
Delsing added, “Our long term goal is to harness quantum physics so that we can benefit from its laws, for example in extremely fast computers. We do this by making electrical circuits which obey quantum laws, that we can control and study.”
“The sound amplitude, or strength, is very weak,” said Göran Johansson, a co-author of the paper. “Basically, when you excite the atom, it creates a sound, one phonon at a time, according to theory. It’s the weakest possible sound possible at the frequency [that it vibrates].”
Johansson quoted that perhaps the future of quantum communications isn’t in quantum light, it’s in quantum sound: “You have time to modify the signal when it propagates,” said Johansson.
“We thought this would be some nice curiosity-driven basic research,” he said. “It’s kind of neat to see what happens when you replace light with sound.”
An artificial atom is an example of a quantum electrical circuit. Just like a regular atom, it can be charged up with energy which it subsequently emits in the form of a particle.
The Chalmers researchers have now succeeded in making acoustic waves couple to an artificial atom.
The frequency used in the experiment is 4.8 gigahertz, approximately close to the microwave frequencies common in modern wireless networks.
The wavelength of the sound becomes short enough to be guided along the surface of a microchip, at such high frequencies.
The sound, known as a surface acoustic wave (SAW) is picked up by a “microphone” composed of interlaced metal fingers.
The theoretical research group recently published a paper on how the acoustic atom functions and appears in the journal Science.