Researchers were able to use sound to communicate with an artificial atom.
The interactions between atoms and light has been studied extensively in the field of quantum optics, but little is known about similar processes involving sound waves, Chalmers University of Technology reported. A research team has succeeded in making acoustic waves couple to an atom
"We have opened a new door into the quantum world by talking and listening to atoms," said Per Delsing, head 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. We do this by making electrical circuits which obey quantum laws, that we can control and study."
In the study an artificial atom was used as an example of a quantum electrical circuit. The artificial atom can be charged with energy which then is emitted in the form of a particle. In most cases this is a light particles, but the atom in this experiment proved to be able to emit and absorb energy in the form of sound.
"According to the theory, the sound from the atom is divided into quantum particles," said Martin Gustafsson, the article's first author. "Such a particle is the weakest sound that can be detected."
Sound moves much slower than light, so the acoustic atom opens up new doors for taking control of quantum phenomena.
"Due to the slow speed of sound, we will have time to control the quantum particles while they travel," Gustafsson said. "This is difficult to achieve with light, which moves 100,000 times more quickly."
The slow speed of sound has a much shorter wavelength than light; atoms that interact with light waves must be much smaller than the wavelength, but in the case of sound the atoms can be larger making their properties easier to control. Researchers can design an atom to couple only to certain acoustic frequencies.
The frequency used in the experiment was 4.8 gigahertz, which is close to the microwave frequencies common in modern wireless networks. This corresponds to the musical note D28, about 20 octaves higher than the highest key on a grand piano. At these frequencies the wavelength of the sound becomes short enough to be guided along the surface of a microchip containing an artificial atom.
The findings were published in a recent edition of the journal Science.