According to recent reports, researchers have developed a “quantum microphone” that can detect the smallest known units of sound- packets of vibrational energy called photons. The new device could also form the basis for more efficient quantum computers.
Phonons have always been impossible to measure because old-fashioned microphones are not nearly sensitive enough to pick them up. A microphone works by identifying when a sound wave interacts with a membrane, but the phonons are so small that they can’t be detected individually due to the Heisenberg Uncertainty Principle.
Instead of staying on indirect measurement of sound waves, scientists have built a device that measures the energy of phonons directly using minuscule resonators which behave like mirrors for sound. The instrument can trap the photons and measure the vibrations they cause, with various energy levels corresponding to various numbers of phonons.
The device is represented in a paper in Nature and could be a step towards the creation of a new type of quantum computer. The ability to spot small packets of sound might allow for devices that encode information using sound energy, allowing the storage of massive amounts of data in a small machine.
A phonon quantum computer could be even more compact and efficient than a quantum computer that uses photons, or particles of light, as phonons are easier to manipulate than photons. If scientists can build a quantum computer using phonons, it could store more data in less space than using photons.
“Right now, people are using photons to encode these states. We want to use phonons, which brings with it a lot of advantages,” said the lead author of the paper, Amir Safavi-Naeini, who is an assistant professor of applied physics at Stanford’s School of Humanities and Sciences. “Our device is a crucial step towards creating a ‘mechanical quantum mechanical’ computer.”