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• Time of issue:2021-08-31 09:59
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(Summary description)The United States developed a phonon laser

Since its invention in 1960, optical lasers have developed into a $10 billion global technology market, and scientists such as Art Ashkin, Gerard Mourou and Donna Strickland have won Nobel Prizes.

Now, researchers from the Rochester Institute of Technology in the United States have collaborated with experts from the University of Rochester to use the optical tweezers technology invented by Ashkin to create a different type of laser: sonic laser.

Optical tweezers

Optical tweezers are a device that uses a highly focused laser beam to generate force (usually on the order of piconewtons) to move tiny transparent objects. Because the force of optical tweezers can directly act on cells and even smaller targets with precision, their applications in science have become more and more extensive. For example, it can be used to move cells or virus particles, pinch cells into various shapes, or cool atoms.

In the latest issue of the journal Nature Photonics, researchers proposed and demonstrated a phonon laser that uses optically suspended nanoparticles. Phonons are energy quantum related to sound waves, and optical tweezers are used to test the limits of quantum effects in isolation and eliminate physical interference from the surrounding environment. The researchers studied the mechanical vibration of nanoparticles, which are suspended under gravity by the radiant force at the focal point of an optical laser beam.

Mishkat Bhattacharya, associate professor of physics and researcher of theoretical quantum optics at Rochester Institute of Technology, said: "The position of the nanoparticles is measured by detecting the light scattered by the nanoparticles, and this information is fed back to the tweezers beam, which allows us to produce a laser-like situation. The vibration becomes strong and fully synchronized, just like electromagnetic waves produced by optical lasers."

Because the waves emitted from the laser pointer are synchronized, the light beam can travel long distances without propagating in all directions, unlike the light from the sun or light bulbs. In standard optical lasers, the characteristics of the light output are controlled by the material from which the laser is made. Interestingly, in phonon lasers, the effects of light and matter are opposite, and the movement of matter particles is now controlled by optical feedback.

Bhattacharya said: "We are very pleased to see such devices with so many and still evolving applications, especially for sensing and information processing."

He also said that the phonon laser is expected to realize the research of basic quantum physics, including the engineering of the famous Schrödinger’s cat thought experiment that can exist in two places at the same time.

Bhattacharya's research team received personal funding from the Office of Naval Research and a comprehensive award led by the University of Rochester.