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Quantum microphone captures extremely weak sound

Date:
February 27, 2012
Source:
Chalmers University of Technology
Summary:
Scientists have demonstrated a new kind of detector for sound at the level of quietness of quantum mechanics. The result offers prospects of a new class of quantum hybrid circuits that mix acoustic elements with electrical ones, and may help illuminate new phenomena of quantum physics.
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Scientists from Chalmers University of Technology have demonstrated a new kind of detector for sound at the level of quietness of quantum mechanics. The result offers prospects of a new class of quantum hybrid circuits that mix acoustic elements with electrical ones, and may help illuminate new phenomena of quantum physics.

The results have been published in Nature Physics.

The "quantum microphone" is based on a single electron transistor, that is, a transistor where the current passes one electron at a time. The acoustic waves studied by the research team propagate over the surface of a crystalline microchip, and resemble the ripples formed on a pond when a pebble is thrown into it. The wavelength of the sound is a mere 3 micrometers, but the detector is even smaller, and capable of rapidly sensing the acoustic waves as they pass by.

On the chip surface, the researchers have fabricated a three-millimeter-long echo chamber, and even though the speed of sound on the crystal is ten times higher than in air, the detector shows how sound pulses reflect back and forth between the walls of the chamber, thereby verifying the acoustic nature of the wave.

The detector is sensitive to waves with peak heights of a few percent of a proton diameter, levels so quiet that sound can be governed by quantum law rather than classical mechanics, much in the same way as light.

"The experiment is done on classical acoustic waves, but it shows that we have everything in place to begin studies of proper quantum-acoustics, and nobody has attempted that before," says Martin Gustafsson, PhD student and first author of the article.

Apart from the extreme quietness, the pitch of the waves is too high for us to hear: The frequency of almost 1 gigahertz is 21 octaves above one-lined A. The new detector is the most sensitive in the world for such high-frequency sound.


Story Source:

Materials provided by Chalmers University of Technology. Note: Content may be edited for style and length.


Journal Reference:

  1. Martin V. Gustafsson, Paulo V. Santos, Göran Johansson, Per Delsing. Local probing of propagating acoustic waves in a gigahertz echo chamber. Nature Physics, 2012; DOI: 10.1038/nphys2217

Cite This Page:

Chalmers University of Technology. "Quantum microphone captures extremely weak sound." ScienceDaily. ScienceDaily, 27 February 2012. <www.sciencedaily.com/releases/2012/02/120227093954.htm>.
Chalmers University of Technology. (2012, February 27). Quantum microphone captures extremely weak sound. ScienceDaily. Retrieved March 19, 2024 from www.sciencedaily.com/releases/2012/02/120227093954.htm
Chalmers University of Technology. "Quantum microphone captures extremely weak sound." ScienceDaily. www.sciencedaily.com/releases/2012/02/120227093954.htm (accessed March 19, 2024).

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