The world’s most sensitive microphone measures individual sound particles

According to Stanford University, the physicists of this institute have developed a “quantum microphone” that can measure individual sound particles, or phonons. These developments could then be useful for creating more efficient and smaller quantum computers based on sound instead of light.

Phonons, like photons, can be considered indivisible quantized packets of energy emitted by atoms. They were conceptually proposed for the first time by Einstein in 1907. As explained by Patricio Arrangoiz-Arriola, one of the authors of the study, the energy of a single phonon is comparable to energy “ten trillion billion times smaller than the energy needed to keep a light bulb on for a second.”

These are values ‚Äč‚Äčthat are difficult to measure, so much so that scientists have never been able to measure phonon states directly in engineered structures. Precisely for this reason, the researchers have developed a sort of very sensitive microphone, defined as the most sensitive microphone in the world, which intercepts the “whispers” of the atoms. A normal microphone would be useless if you want to intercept a phonon since the position of any quantum object cannot be determined a priori. The same act of measurement with a normal microphone would change the energy level of the phonons that you intend to measure.

The quantum microphone, on the other hand, uses special tiny super-cooled nanomechanical resonators, visible only under a microscope. The same resonators are then coupled to a superconducting circuit that forms a qubit, ie a quantum bit that can exist in two states simultaneously.

With this complex device, researchers able to accurately detect phonons, which could help create new types of quantum devices that can store or decode information based on sound particles.