Making sound ‘chill out’

Light can be used to cool sound waves traveling within solid materials.

Cooling sound waves with light involves converting sound energy into light energy, which changes the color of the light. (Image credit: Eric Kittlaus and Nils Otterstrom)
Cooling sound waves with light involves converting sound energy into light energy, which changes the color of the light. (Image credit: Eric Kittlaus and Nils Otterstrom)

Yale scientists have discovered a new method to cool down sound waves in a silicon chip. The discovery is expected to revolutionize atomic physics.

To do this, scientists developed a special type of nano-scale silicon structure that allows propagating light and sound waves to interact a special type of nano-scale silicon structure that allows propagating light and sound waves to interact.

Peter Rakich, an associate professor of applied physics at Yale who led the research said, “By tailoring the optical and acoustic properties of these waveguides, we’ve been able to enhance and shape the interaction between light and sound. This is the key that allows us to reduce the energy carried by thermally excited sound waves.”

At the point when a photon cooperates with sound waves proliferating in a strong, it scrambles to various shades of light. At the point when the photon winds up red-moved, it loses a part of its energy, granting it to the sound wave. All the while, the light assimilates the acoustic vitality and diverts it as a blue-shifted photon. This second procedure moderates the movement of the sound wave, conveying it to a lower compelling temperature.

Eric Kittlaus, a Yale Ph.D. student and co-author of the study said, “Normally these two opposing processes would counteract and balance out. However, we designed a waveguide in which a certain group of sound waves only experience the cooling process. We call this symmetry breaking, and it’s the essential ingredient for the cooling process to dominate.”

First author Nils Otterstrom, a Yale Ph.D. student, noted, “We were surprised by the strength of the cooling effect. It led the team to develop a rigorous theoretical framework for understanding the phenomena, as well as coming up with systematic experimental studies.”

“We now have a knob that allows us to control processes that are at the heart of emerging chip-scale technology, including new types of lasers, gyroscopes, and signal processing systems.”

Rakich said, “We are really excited about where this work may lead. We now have the ability to tame and control noise in a large range of systems that are crucial to communication, information processing, and measurement in a way that we never had before.”

Their findings appear in the Nov. 27 online edition of the journal Physical Review X.

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